linux/Documentation/memory-barriers.txt
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   1                         ============================
   2                         LINUX KERNEL MEMORY BARRIERS
   3                         ============================
   4
   5By: David Howells <dhowells@redhat.com>
   6    Paul E. McKenney <paulmck@linux.vnet.ibm.com>
   7
   8Contents:
   9
  10 (*) Abstract memory access model.
  11
  12     - Device operations.
  13     - Guarantees.
  14
  15 (*) What are memory barriers?
  16
  17     - Varieties of memory barrier.
  18     - What may not be assumed about memory barriers?
  19     - Data dependency barriers.
  20     - Control dependencies.
  21     - SMP barrier pairing.
  22     - Examples of memory barrier sequences.
  23     - Read memory barriers vs load speculation.
  24     - Transitivity
  25
  26 (*) Explicit kernel barriers.
  27
  28     - Compiler barrier.
  29     - CPU memory barriers.
  30     - MMIO write barrier.
  31
  32 (*) Implicit kernel memory barriers.
  33
  34     - Locking functions.
  35     - Interrupt disabling functions.
  36     - Sleep and wake-up functions.
  37     - Miscellaneous functions.
  38
  39 (*) Inter-CPU locking barrier effects.
  40
  41     - Locks vs memory accesses.
  42     - Locks vs I/O accesses.
  43
  44 (*) Where are memory barriers needed?
  45
  46     - Interprocessor interaction.
  47     - Atomic operations.
  48     - Accessing devices.
  49     - Interrupts.
  50
  51 (*) Kernel I/O barrier effects.
  52
  53 (*) Assumed minimum execution ordering model.
  54
  55 (*) The effects of the cpu cache.
  56
  57     - Cache coherency.
  58     - Cache coherency vs DMA.
  59     - Cache coherency vs MMIO.
  60
  61 (*) The things CPUs get up to.
  62
  63     - And then there's the Alpha.
  64
  65 (*) Example uses.
  66
  67     - Circular buffers.
  68
  69 (*) References.
  70
  71
  72============================
  73ABSTRACT MEMORY ACCESS MODEL
  74============================
  75
  76Consider the following abstract model of the system:
  77
  78                            :                :
  79                            :                :
  80                            :                :
  81                +-------+   :   +--------+   :   +-------+
  82                |       |   :   |        |   :   |       |
  83                |       |   :   |        |   :   |       |
  84                | CPU 1 |<----->| Memory |<----->| CPU 2 |
  85                |       |   :   |        |   :   |       |
  86                |       |   :   |        |   :   |       |
  87                +-------+   :   +--------+   :   +-------+
  88                    ^       :       ^        :       ^
  89                    |       :       |        :       |
  90                    |       :       |        :       |
  91                    |       :       v        :       |
  92                    |       :   +--------+   :       |
  93                    |       :   |        |   :       |
  94                    |       :   |        |   :       |
  95                    +---------->| Device |<----------+
  96                            :   |        |   :
  97                            :   |        |   :
  98                            :   +--------+   :
  99                            :                :
 100
 101Each CPU executes a program that generates memory access operations.  In the
 102abstract CPU, memory operation ordering is very relaxed, and a CPU may actually
 103perform the memory operations in any order it likes, provided program causality
 104appears to be maintained.  Similarly, the compiler may also arrange the
 105instructions it emits in any order it likes, provided it doesn't affect the
 106apparent operation of the program.
 107
 108So in the above diagram, the effects of the memory operations performed by a
 109CPU are perceived by the rest of the system as the operations cross the
 110interface between the CPU and rest of the system (the dotted lines).
 111
 112
 113For example, consider the following sequence of events:
 114
 115        CPU 1           CPU 2
 116        =============== ===============
 117        { A == 1; B == 2 }
 118        A = 3;          x = A;
 119        B = 4;          y = B;
 120
 121The set of accesses as seen by the memory system in the middle can be arranged
 122in 24 different combinations:
 123
 124        STORE A=3,      STORE B=4,      x=LOAD A->3,    y=LOAD B->4
 125        STORE A=3,      STORE B=4,      y=LOAD B->4,    x=LOAD A->3
 126        STORE A=3,      x=LOAD A->3,    STORE B=4,      y=LOAD B->4
 127        STORE A=3,      x=LOAD A->3,    y=LOAD B->2,    STORE B=4
 128        STORE A=3,      y=LOAD B->2,    STORE B=4,      x=LOAD A->3
 129        STORE A=3,      y=LOAD B->2,    x=LOAD A->3,    STORE B=4
 130        STORE B=4,      STORE A=3,      x=LOAD A->3,    y=LOAD B->4
 131        STORE B=4, ...
 132        ...
 133
 134and can thus result in four different combinations of values:
 135
 136        x == 1, y == 2
 137        x == 1, y == 4
 138        x == 3, y == 2
 139        x == 3, y == 4
 140
 141
 142Furthermore, the stores committed by a CPU to the memory system may not be
 143perceived by the loads made by another CPU in the same order as the stores were
 144committed.
 145
 146
 147As a further example, consider this sequence of events:
 148
 149        CPU 1           CPU 2
 150        =============== ===============
 151        { A == 1, B == 2, C = 3, P == &A, Q == &C }
 152        B = 4;          Q = P;
 153        P = &B          D = *Q;
 154
 155There is an obvious data dependency here, as the value loaded into D depends on
 156the address retrieved from P by CPU 2.  At the end of the sequence, any of the
 157following results are possible:
 158
 159        (Q == &A) and (D == 1)
 160        (Q == &B) and (D == 2)
 161        (Q == &B) and (D == 4)
 162
 163Note that CPU 2 will never try and load C into D because the CPU will load P
 164into Q before issuing the load of *Q.
 165
 166
 167DEVICE OPERATIONS
 168-----------------
 169
 170Some devices present their control interfaces as collections of memory
 171locations, but the order in which the control registers are accessed is very
 172important.  For instance, imagine an ethernet card with a set of internal
 173registers that are accessed through an address port register (A) and a data
 174port register (D).  To read internal register 5, the following code might then
 175be used:
 176
 177        *A = 5;
 178        x = *D;
 179
 180but this might show up as either of the following two sequences:
 181
 182        STORE *A = 5, x = LOAD *D
 183        x = LOAD *D, STORE *A = 5
 184
 185the second of which will almost certainly result in a malfunction, since it set
 186the address _after_ attempting to read the register.
 187
 188
 189GUARANTEES
 190----------
 191
 192There are some minimal guarantees that may be expected of a CPU:
 193
 194 (*) On any given CPU, dependent memory accesses will be issued in order, with
 195     respect to itself.  This means that for:
 196
 197        Q = P; D = *Q;
 198
 199     the CPU will issue the following memory operations:
 200
 201        Q = LOAD P, D = LOAD *Q
 202
 203     and always in that order.
 204
 205 (*) Overlapping loads and stores within a particular CPU will appear to be
 206     ordered within that CPU.  This means that for:
 207
 208        a = *X; *X = b;
 209
 210     the CPU will only issue the following sequence of memory operations:
 211
 212        a = LOAD *X, STORE *X = b
 213
 214     And for:
 215
 216        *X = c; d = *X;
 217
 218     the CPU will only issue:
 219
 220        STORE *X = c, d = LOAD *X
 221
 222     (Loads and stores overlap if they are targeted at overlapping pieces of
 223     memory).
 224
 225And there are a number of things that _must_ or _must_not_ be assumed:
 226
 227 (*) It _must_not_ be assumed that independent loads and stores will be issued
 228     in the order given.  This means that for:
 229
 230        X = *A; Y = *B; *D = Z;
 231
 232     we may get any of the following sequences:
 233
 234        X = LOAD *A,  Y = LOAD *B,  STORE *D = Z
 235        X = LOAD *A,  STORE *D = Z, Y = LOAD *B
 236        Y = LOAD *B,  X = LOAD *A,  STORE *D = Z
 237        Y = LOAD *B,  STORE *D = Z, X = LOAD *A
 238        STORE *D = Z, X = LOAD *A,  Y = LOAD *B
 239        STORE *D = Z, Y = LOAD *B,  X = LOAD *A
 240
 241 (*) It _must_ be assumed that overlapping memory accesses may be merged or
 242     discarded.  This means that for:
 243
 244        X = *A; Y = *(A + 4);
 245
 246     we may get any one of the following sequences:
 247
 248        X = LOAD *A; Y = LOAD *(A + 4);
 249        Y = LOAD *(A + 4); X = LOAD *A;
 250        {X, Y} = LOAD {*A, *(A + 4) };
 251
 252     And for:
 253
 254        *A = X; Y = *A;
 255
 256     we may get either of:
 257
 258        STORE *A = X; Y = LOAD *A;
 259        STORE *A = Y = X;
 260
 261
 262=========================
 263WHAT ARE MEMORY BARRIERS?
 264=========================
 265
 266As can be seen above, independent memory operations are effectively performed
 267in random order, but this can be a problem for CPU-CPU interaction and for I/O.
 268What is required is some way of intervening to instruct the compiler and the
 269CPU to restrict the order.
 270
 271Memory barriers are such interventions.  They impose a perceived partial
 272ordering over the memory operations on either side of the barrier.
 273
 274Such enforcement is important because the CPUs and other devices in a system
 275can use a variety of tricks to improve performance, including reordering,
 276deferral and combination of memory operations; speculative loads; speculative
 277branch prediction and various types of caching.  Memory barriers are used to
 278override or suppress these tricks, allowing the code to sanely control the
 279interaction of multiple CPUs and/or devices.
 280
 281
 282VARIETIES OF MEMORY BARRIER
 283---------------------------
 284
 285Memory barriers come in four basic varieties:
 286
 287 (1) Write (or store) memory barriers.
 288
 289     A write memory barrier gives a guarantee that all the STORE operations
 290     specified before the barrier will appear to happen before all the STORE
 291     operations specified after the barrier with respect to the other
 292     components of the system.
 293
 294     A write barrier is a partial ordering on stores only; it is not required
 295     to have any effect on loads.
 296
 297     A CPU can be viewed as committing a sequence of store operations to the
 298     memory system as time progresses.  All stores before a write barrier will
 299     occur in the sequence _before_ all the stores after the write barrier.
 300
 301     [!] Note that write barriers should normally be paired with read or data
 302     dependency barriers; see the "SMP barrier pairing" subsection.
 303
 304
 305 (2) Data dependency barriers.
 306
 307     A data dependency barrier is a weaker form of read barrier.  In the case
 308     where two loads are performed such that the second depends on the result
 309     of the first (eg: the first load retrieves the address to which the second
 310     load will be directed), a data dependency barrier would be required to
 311     make sure that the target of the second load is updated before the address
 312     obtained by the first load is accessed.
 313
 314     A data dependency barrier is a partial ordering on interdependent loads
 315     only; it is not required to have any effect on stores, independent loads
 316     or overlapping loads.
 317
 318     As mentioned in (1), the other CPUs in the system can be viewed as
 319     committing sequences of stores to the memory system that the CPU being
 320     considered can then perceive.  A data dependency barrier issued by the CPU
 321     under consideration guarantees that for any load preceding it, if that
 322     load touches one of a sequence of stores from another CPU, then by the
 323     time the barrier completes, the effects of all the stores prior to that
 324     touched by the load will be perceptible to any loads issued after the data
 325     dependency barrier.
 326
 327     See the "Examples of memory barrier sequences" subsection for diagrams
 328     showing the ordering constraints.
 329
 330     [!] Note that the first load really has to have a _data_ dependency and
 331     not a control dependency.  If the address for the second load is dependent
 332     on the first load, but the dependency is through a conditional rather than
 333     actually loading the address itself, then it's a _control_ dependency and
 334     a full read barrier or better is required.  See the "Control dependencies"
 335     subsection for more information.
 336
 337     [!] Note that data dependency barriers should normally be paired with
 338     write barriers; see the "SMP barrier pairing" subsection.
 339
 340
 341 (3) Read (or load) memory barriers.
 342
 343     A read barrier is a data dependency barrier plus a guarantee that all the
 344     LOAD operations specified before the barrier will appear to happen before
 345     all the LOAD operations specified after the barrier with respect to the
 346     other components of the system.
 347
 348     A read barrier is a partial ordering on loads only; it is not required to
 349     have any effect on stores.
 350
 351     Read memory barriers imply data dependency barriers, and so can substitute
 352     for them.
 353
 354     [!] Note that read barriers should normally be paired with write barriers;
 355     see the "SMP barrier pairing" subsection.
 356
 357
 358 (4) General memory barriers.
 359
 360     A general memory barrier gives a guarantee that all the LOAD and STORE
 361     operations specified before the barrier will appear to happen before all
 362     the LOAD and STORE operations specified after the barrier with respect to
 363     the other components of the system.
 364
 365     A general memory barrier is a partial ordering over both loads and stores.
 366
 367     General memory barriers imply both read and write memory barriers, and so
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 320     5onsid52umentenepreplaciarriond loadefore e compianyinects of "Doc ili mimentation/memory-barriers.txt#L313" id="L313" cla5s="line" 5ame="L321"> 321     5nder 52umentation/memory-barriers.txt#L282" id="L282" cla5s="line" 5ame="L322"> 322     5oad t52umentrol alsoa="Doc informatiati
 323     5ime t52umentation/memory-barriers.txt#L244" id="L244" cla5s="line" 5ame="L324"> 324     5ouche52umentation/memory-barriers.txt#L285" id="L285" cla5s="line" 5ame="L325"> 325     5epend5ncy baCONTROL DEPENDENCIEnation/memory-barriers.txt#L285" id="L285" cla5s="line" 5ame="L326"> 326
 327     5ee th52umentation/memory-barriers.txt#L318" id="L318" cla5s="line" 5ame="L328"> 328     5howin52oned Ay.  If the address nct"Docuser or better uences" s,dndensd writaumentation/memory-barriers.txt#L325" id="L325" cla5s="line" 5ame="L329"> 329
 330     5!] No5e thataodetation/memory-barriers.txt#L286" id="L286" cla5s="line" 5ame="L331"> 331     5ot a 53umentation/memory-barriers.txt#L282" id="L282" cla5s="line" 5ame="L332"> 332     5n the532 = LOAD {*A,q,  &atation/memory-barriers.txt#L335" id="L335" cla5s="line" 5ame="L333"> 333     5ctual533*A = X; Y = if (p)ation/memory-barriers.txt#L244" id="L244" cla5s="line" 5ame="L334"> 334     5 full534*A = Y = X;








q,  &btation/memory-barriers.txt#L335" id="L335" cla5s="line" 5ame="L335"> 335     5ubsec535AD *B,  X = <rrier would be required
gntation/memory-barriers.txt#L335" id="L335" cla5s="line" 5ame="L336"> 336
 337     5!] No53umentation/memory-barriers.txt#L318" id="L318" cla5s="line" 5ame="L338"> 338     5rite 538ill r:
 339
 340
 341 (3) 5ead (541 = Lct"Documesetation/memory-barriers.txt#L286" id="L286" cla5s="line" 5ame="L342"> 342
 343     5 read543 = LOAD {*A,q,  &atation/memory-barriers.txt#L335" id="L335" cla5s="line" 5ame="L344"> 344     5OAD o544*A = X; Y = if (p)ation/memory-barriers.txt#L244" id="L244" cla5s="line" 5ame="L345"> 345     5ll th545*A = X; Y =         q,  &btation/memory-barriers.txt#L335" id="L335" cla5s="line" 5ame="L346"> 346     5ther 54OAD *B,  X = <ld normally 
gntation/memory-barriers.txt#L335" id="L335" cla5s="line" 5ame="L347"> 347
 348     5 read54umentation/memory-barriers.txt#L289" id="L289" cla5s="line" 5ame="L349"> 349     5ave a54umentation/memory-barriers.txt#L170" id="L170" cla5s="line" 5ame="L350"> 350
 351     5ead m5cumentment-
 352     5or th55umentation/memory-barriers.txt#L343" id="L343" cla5s="line" 5ame="L353"> 353
 354     5!] No5 X; Y  305 (2) 5at5truct therriond loa6338y-barr28cume line" 4ame="L358"> 3583pltid="L282" cla5s="line" 5ame="L332"> 33261ref="D2" cla35L289" id="L289" 4ee th455AD *A,  STORB,  4tation/5emory5516" id="L216" cla5s="line" 5ame="L316"> 316    h4ef="D455AD *B,  X = < href="D5cume
5ntatioAy-barriers.txt;
 316    h5ef="D547AD *B,  STORP,  &tat5on/me5ory-baemory-bar40" /memooth loadtation/mwa334UNrsos.txt#txt#="Doimilart#L32iersd="L216" cla5s="line" 5ame="L316"> 316    h5 read54u*A = X; Y =             5   Q,5 Ptatitation/memobe hat  anyinscttntation/m
 316    h5ave a54u*A = Y = X;












5


, 5X*Qtat-barriers.txtar40" /m, ag cl,emooth loadtation/ms
,i#txt#id="L286" cla5s="line" 5ame="L342"> 342
 361   5 4perat4o5s spT per dependenclre a5riers56rriers.txt#L3-barriers.txt#L252" id="L252" cla5s="line" 5ame="L307"> 307     4he LO4D5and  operati, Q,hat  any5barri56ory-barriers.ion/memory-barriers.txt#L252" id="L252" cla5s="line" 5ame="L308"> 308     4he ot465mentation/memory-barrier5.txt#56ory-barriers.a5" iid="L335" cla5s="line" 5ame="L348"> 348    h4ef="D465; Y = *A;
 311     4 gene465; Y = *A;
 346    h4ef="D4c5mentation/memory-barrier5.txt#56rrier would be required
gntation/iers.txt#L335" id="L335" cla5s="line" 5ame="L347"> 347
 344     4>    4t5e otlrede compitnces:
 349    t4 rest4c5mentation/memory-barrier5.txt#5170" iOrid="L286" cla5s="line" 5ame="L342"> 342
 271Mem5r4 barr475mentation/memory-barrier5.txt#57rriers.txt#L3-barriers.txt#L252" id="L252" cla5s="line" 5ame="L307"> 307    r4ng ov475mentWhilsoblem fa hrbarn5likgs57ory-barriers.ion/memory-barriers.txt#L252" iiiiiiiiiiiiiiiiid="L252" cla5s="line" 5ame="L307"> 307    r4he ot465mentisn depet,Documenif 5whavi57ory-barriers.a5" iid="L335" cla5s="line" 5ame="L348"> 348     4nforc475mentAlphantation/memory-5arrie57s (D, h 1)ati-barriers.txt#L335" id="L335" cla5s="line" 5ame="L311"> 311    u4e a v475mentation/memory-barrier5.txt#57s (D, h 4)atib5" L335" irs.txt#L2L335 id="L335" cla5s="line" 5ame="L346"> 346    r4al an475s spro da _epeothenify b5rrier57rrier would be required
gntation/memory-barriers.txt#L335" id="L335" cla4s="line" 4ame="L287"> 287 (15c4 pred4c5ion aetwdento then it#a hro57*Qtation/memory-barriers.txt#y335*xid="L335" cla4s="line" 4ame="L287"> 287 (15c4>    4t5mentation/memory-barrier5.txt#5289" id="L289" cla4s="line" 4ame="L279"> 279int5r4ction475 = LOAD {*A,as c1AD {*A,5,,,as5c2atioBasic5" i,xtcum.hredtation/mNrafterhxt#Lo 330    h4ef="D485 = LOAD {*A, href="Docum5nt, h58 e compiaetatioweakxt#L224"ion/m5ame="L332"> 33261ref="D2" cla35L289" id="L289"h4ef="D485; Y = *A;
 282VAR5E4IES O485AD *A,  STORB,  4tation/5emory58ef=unasds tuiative=itr lerre before
 349   5-4-----485AD *B,  X = < href="D5cume
58scumenttsation/riers.ts.txt#L36Control dependenty hmporay lompitnceRCUwed t#L282ntatd="L349" class="line" name="L349"> 349   5-4nforc475AD *B,  STORP,  &tat5on/me5ory-bav49 342
 316    h4ef="D485*A = X; Y =             5   &l582ation/memory-barriers.txt#L2222222222222222252" id="L252" cla5s="line" 5ame="L307"> 307     4rite 485*A = Y = X;












5


, 58f="Documentation/memory-barriiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiid="L252" cla5s="line" 5ame="L307"> 307    h4ef="D4c5mentation/memory-barrier5.txt#588ry-barriers.a5" iiiiiiiiiiiii}5" iiii" i5" i{  v5" cd="L252" cla5s="line" 5ame="L307"> 307    h4ction475ill r:
 316     4pecif495mentenirdn"Documilito th5n bri59tation/memory-barriers.txt#L335" in/memory\n/memory-bariers.txt#L335" id="L335" cla5s="line" 5ame="L347"> 347
 344     4ompon4n5s offirst load reall
 346    h4ef="D4c5mentmrrierr
 294   5 4 writ495atioe me-numbeive.  cer 5err
<5985" id="L285" cla5s="line" 5ame="L325"> 325     4o hav4 5ny elerr
erceivo"oey  su5 migh5 bthatEXAMPLES OFriers.txt#L264" SEQUENC id="L285" cla5s="line" 5ame="L326"> 326
 352     4 CPU 495 meme me-numbeive.bankde5uence5918" id="L318" cla5s="line" 5ame="L338"> 338     4emory4s5stemodd-numbeive.bankdse5tdie,5ng somFence i,xers.txt#L355" t#L3txt#f="Documentationstxt#L350".txt#L364" id="L364" class="line" name="L286"> 286
 351   6h5ef="D5c6mentation/memory-barrier6.txt#6301" id="L301" cla5s="line" 5ame="L301"> 301   6 5!] No506mentation/memory-barrier6.txt#60rriers.txt#L3-barrd="L301" cla5s="line" 5ame="L301"> 301   6 2!] No506m offirst load reall
 307   6h5ef="D5c6mentnumbei the & hrthen 6ly bo60ory-barriers.espectA5" id="L335" cla5s="line" 5ame="L312"> 312   6h5ef="D5c6mentrged otation/memory-6arrie604ry-barriers.espect355"id="L252" cla5s="line" 5ame="L307"> 307   6 5ata d506mentation/memory-barrier6.txt#605ry-barriers.espectationd="L252" cla5s="line" 5ame="L307"> 307   6 6ata d506ment="DoassueB mighs bth6,,,as60tation/memory-barriers.txt#L335" id="L335" cla4s="line" 4ame="L357"> 357
 357
 357
 350
 350
 299   6 5btain516 = LOAD {*A,,,,,        6   Q,6 Ptatiespect3,.espectat}txt#Licfterxt#L3fore
 299   6 5ef="D5c6*A = X; Y =             6   &l6;rrier}id="L286" cla4s="line" 4ame="L351"> 351   6 5 data516*A = Y = X;












6


, 6185" id="L285" cla5s="line" 5ame="L325"> 325   6 5nly; 5c6mentation/memory-barrier6.txt#615ry-barriers.+L285" i+rriers.:riers.:d="L285" cla5s="line" 5ame="L325"> 325   6 6ata d506mentation/memory-barrier6.txt#61tation/memory|/memory|/memory+L285" +d="L285" cla5s="line" 5ame="L325"> 325   6 5 data506mentThrfrriers should no6mally617ation/memory|/memory|L285" 5" i| C=3ry|/memo}#L2  /\d="L285" cla5s="line" 5ame="L325"> 325   6 8 data506ned rol rcu_ceivff tnce(6aiepi618ation/memory|/memory|/m:mory+L285" +iiiii}5" i-ry\n/285" 5" i E286" m-barrierxt#L id="L349" class="line" name="L349"> 349   6 5ommit5i6g send load is i RCU dep6de"oe619ation/memory|/memory|/m:mory| A=1ry|/memo}#L2     \/L2     itr re ters.txt#L364" d="L349" class="line" name="L349"> 349   6 5onsid526mentenepreplaciarriond l6adefo620ation/memory|/memory|/m:mory+L285" +iiiii}d="L349" class="line" name="L349"> 349   6 5!] No506mentation/memory-barrier6.txt#621ation/memory|/-barri|/m:mory| B=2ry|/memo}d="L349" class="line" name="L349"> 349   6 5btain516mentrol alsoa="Doc infor6atiat622ation/memory|/memory|/memory+L285" +/memo}d="L349" class="line" name="L349"> 349   6 5ef="D5c6mentation/memory-barrier6.txt#623ation/memory|/memory|/mewwwwwwwwwwwwwwwwo}#L2-bar i-rAe=ituer moda 349   6 5 data516mentation/memory-barrier6.txt#624ation/memory|/memory|/memory+L285" +/memo}n/memory s,dndensdesaterre bprior" icomad="L349" class="line" name="L349"> 349   6 5nly; 5c6y baCONTROL DEPENDENCIEn6tion/625ation/memory|/memory|/m:mory| E=5ry|/memo}#L2     forC perceins thmmitt49"b45" id="L345" class="line" 3ame="L289"> 289   6h5ef="D526poneument-
 289   6h5 data506mentation/memory-barrier6.txt#627ation/memory|/memory|L285" 5" i| D=4ry|/memo}d="L349" class="line" name="L349"> 349   6 8 data506ned Ay.  If the address 6ct"Do628ation/memory|/memory|/memory+L285" +d="L349" class="line" name="L349"> 349   6 5ommit5i6g ses should normally  m6i tar629ry-barriers.+L285" i+rriers.:riers.:d="L285" cla5s="line" 5ame="L325"> 325   6 5!] No5e6thataodetation/memory-ba6riers63I/pci0" cation/meeeeeeeeeeeeeeee|d="L285" cla5s="line" 5ame="L325"> 325   6 5!] No506mentation/memory-barrier6.txt#63A-API-HOWTO0" cateeeeeeeeeeeeeee| Srriers.t storesattio.txt ksetommitt49" icomad="L285" cla5s="line" 5ame="L325"> 325   6 5btain516 = LOAD {*A,q,  &ata6ion/m63Ptation/memory-barriers.txt#Leee|  nc5atiL364" nby3-barrd="L301" cla5s="line" 5ame="L301"> 301   6 5ctual536*A = X; Y = if (p)ation/6emory63rrier would be required
gntattttVd="L301" cla5s="line" 5ame="L301"> 301   6 5 data516*A = Y = X;








q,  6amp;b6385" id="L285" cla5s="line" 5ame="L325"> 325   6 5ubsec536AD *B,  X = <rrier wo6ld be6316" id="L216" cla5s="line" 5ame="L316"> 316   6h5ef="D536 = LOAD {*A,x  X*qtation6memor6-barriSry-ba i,xmporay lompitnceRCUwed  t#L3txt#f="Documentationstxt#mpor-y lompitid="L340" cla5s="line" 5ame="L320"> 320   6 5!] No536mentation/memory-barrier6.txt#6318" irierstion/memory-barriers.txt#Larriers.txt#L286" id="L286" cla4s="line" 4ame="L351"> 351   6 5rite 536ill r:
 279int6h5ef="D536g ses should ncy is f="D6cucy.632ation/memory-barriers.txt#L2n/memory-barid="L252" cla5s="line" 5ame="L307"> 307   6h5ef="D546 = Latas
pte compipcumic6 thro64f="Documentation/memory-barrory-barriers.txt#L252" iiiiiiiiid="L252" cla5s="line" 5ame="L307"> 307   6h5!] No506 = Lct"Documesetation/me6ory-b6MA-API-HOWTO0" cattttt{t355"7; X55"9; Y55"8;tatioL335"Yo}d="L349" class="line" name="L349"> 349   6h5ef="D5c6mentation/memory-barrier6.txt#6MA-API0" catioespectA5" id="L335" cla5s="line" 5ame="L312"> 312   6 5 read546 = LOAD {*A,q,  &ata6ion/m64ory-barriers.espect355"id="L252" cla5s="line" 5ame="L307"> 307   6 5OAD o546*A = X; Y = if (p)ation/6emory64s (D, h 1)ati-barriers.txt#L335" id="L335" cla5s="line" 5ame="L311"> 311   6 5ll th546*A = X; Y =         q,  6amp;b645ry-barriers.espectatio#L276"TO0" catttttLOAD Xd="L335" cla5s="line" 5ame="L311"> 311   6 5ef="D536AD *B,  X = <ld norma6ly 
g6tation/memory-espectt#L34 TO0" catttttLOAD C (ge" m#L276" d="L335" cla5s="line" 5ame="L311"> 311   6 5!] No536 = LOAD {*A,x  X*qtation6memor64*Qtation/memory-barriers.txt# catttttLOAD *C (ierss " d="L335" cla5s="line" 5ame="L311"> 311   6 5rite 536mentation/memory-barrier6.txt#6289" id="L289" cla5s="line" 5ame="L349"> 349   6 5ave a546mentation/memory-barrier6.txt#6170" iW340" iation/meme" 5,y-barit#L27-barrs atrs.tx286" mony-barri st-entd="L289" cla5s="line" 5ame="L349"> 349   6h5ef="D5c6mentg&quBDocume PAIRINGa6ion/m6mory-bumentas aDocuandommentat, hlhpit
 351   6 5ead m5c6mentment-
 352   6 5or th556mentation/memory-barrier6.txt#6c2ation/memory+L285" i+rriers.:riers.:ers.txt# cattttt:ers.txtid="L286" cla4s="line" 4ame="L351"> 351   6 5 read546 = LWnrnDda _e cos;
 351   6 5OAD o546; Y  305 (2) 5at5tru6t the654ation/memory|/memory|L285" 5" i| B=2ry|5" i-ryyyyyy5" 5" i| Y 5" i8ry|/m|txt#-barriers.txid="L216" cla5s="line" 5ame="L316"> 316   6 4ee th456AD *A,  STORB,  4tation/6emory655ation/memory|/memory|/m:mory+L285" +     \n/memory  +L285" i+rr| -barid="L252" cla5s="line" 5ame="L307"> 307   6h4ef="D456AD *B,  X = < href="D6cume
65tation/memory|/-barri|/m:mory| A=1ry|/memo \n/mem5" 5" i| C 5" iL335"Yo|ttVd="L301" cla5s="line" 5ame="L301"> 301   6h5ef="D546AD *B,  STORP,  &tat6on/me657ation/memory|/memory|/memory+L285" +       |/memory +L285" i+d="L301" cla5s="line" 5ame="L301"> 301   6h5rite 536*A = X; Y =             6   Q,658ation/memory|/memory|/mewwwwwwwwwwwwwwwwo  |/memory :ers.txtid="L286" cla4s="line" 4ame="L351"> 351   6 5ave a546*A = Y = X;












6


, 659ation/memory|/memory|/memory+L285" +       |/memory :ers.txtid="L286" cla4s="line" 4ame="L351"> 351   6 4 gene4c6mentation/memory-barrier6.txt#660ation/memory|/memory|/m:mory| C=#L276"T| i-ryyy|/memory :ers.txtimemory +L285" i+d="L301" cla5s="line" 5ame="L301"> 301   6 4perat4o6s spT per dependenclre a6riers661ation/memory|/memory|/m:mory+L285" +   \   |/memory +L285" i+/memory|/memory|d="L301" cla5s="line" 5ame="L301"> 301   6 5or th556and  operati, Q,hat  any6barri662ation/memory|/memory|L285" 5" i| D=4ry|/memtxt#L285" i5" i| C 5" iL335"By|L285" 5" i| memory|d="L301" cla5s="line" 5ame="L301"> 301   6 5 read546mentation/memory-barrier6.txt#663ation/memory|/memory|/memory+L285" +       |/memory +L285" i+/memory|/memory|d="L301" cla5s="line" 5ame="L301"> 301   6 5OAD o546; Y = *A;
 301   6 4ee th456; Y = *A;
 301   6 4ef="D456mentation/memory-barrier6.txt#66rrier would be required
gntatLLLLLLLLLLLLLLL|/memory :ers.txtimemory |/-barit|d="L301" cla5s="line" 5ame="L301"> 301   6 5ef="D546emorBut!,,as c2 depend l6ads i66*Qtation/memory-barriers.txt#LLLLLLLLLLLLLLL|/memory +L285" i+/memory|/memory|d="L301" cla5s="line" 5ame="L301"> 301   6 5rite 536e otlrede compitnces:
 301   6 5ave a546mentation/memory-barrier6.txt#66*Qtation/memory-b-barriers.txt#L (!)LLLLLLLL|/memory +L285" i+/memory|/memory|d="L301" cla5s="line" 5ame="L301"> 301   6h4ef="D476; Y = *A;
 301   6r4 barr476mentation/memory-barrier6.txt#67A-API-HOWTO0" cateeeeeeeeeeeeeeeLLLLLLLLLLLL|/memory +L285" i+/memory|/memory|d="L301" cla5s="line" 5ame="L301"> 301   6h5or th556mentWhilsoblem fa hrbarn6likgs67Ptation/memory-baTon/riertxt#X holss 5" 5" i L  \n/memor| X 5" i9 y|L285" 5" i| memory|d="L301" cla5s="line" 5ame="L301"> 301   6r4he ot466mentisn depet,Documenif 6whavi67rrier would be reupcomal rs.txt#L34would be re\emory +L285" i+/memory|/memory|d="L301" cla5s="line" 5ame="L301"> 301   6h5OAD o546mentAlphantation/memory-6arrie67tion/memory-barriorderincatietxt#L             285" 5" i| B 5" i2 y|/memory+L285" i+d="L301" cla5s="line" 5ame="L301"> 301   6u4e a v476mentation/memory-barrier6.txt#67Ptation/memory-barriers.txt#LLLLLLLLLLLLLLLLLLLLLLLLL+L285" i+d="L301" cla5s="line" 5ame="L301"> 301   6u4ef="D456s spro da _epeothenify b6rrier67rrier would be required
gntattttttttttttttttttttttttt:ers.txtid="L286" cla4s="line" 4ame="L351"> 351   6c4 pred4c6ion aetwdento then it$a hro6718" id="L318" cla5s="line" 5ame="L338"> 338   6c4>    4t6mentation/memory-barrier6.txt#6289" id="L289" cla4s="line" 4ame="L279"> 279int6r4ction476 = LOAD {*A,as c1AD {*A,6,,,as6c2atioIa htatibove
ation/mem-barit-barrs alu"DoctBms
,7, hlhpit
 274Suc6h4ef="D486 = LOAD {*A, href="Docum6nt, h68 e co(oresatwf="Dobe B)etomxt#Lts.txt#L36LOAD xt#Cid="L364" class="line" name="L286"> 286
 282VAR6E4IES O486AD *A,  STORB,  4tation/6emory68ef=unIf, howevd t#Le hat  anyinscttntation/mw-barceins ,rs;
 274Suc6h4he ot466AD *B,  X = < href="D6cume
68scumenumbeiveriertxt#*i (ie: B)eony-bar2id="L286" cla4s="line" 4ame="L351"> 351   6-4nforc476AD *B,  STORP,  &tat6on/me6885" id="L285" cla5s="line" 5ame="L325"> 325   6r4 barr486*A = X; Y =             6   Q,6 Ptation/memor-barriers.txt#L2n/memory-barid="L252" cla5s="line" 5ame="L307"> 307   6h4ef="D486*A = X; Y =             6   &l682ation/memoryion/memory-barrory-barriers.txt#L252" iiiiiiiiid="L252" cla5s="line" 5ame="L307"> 307   6 4rite 486*A = Y = X;












6


, 6X*Qtation/memory-barri{t355"7; X55"9; Y55"8;tatioL335"Yo}d="L349" class="line" name="L349"> 349   6h4ef="D4c6mentation/memory-barrier6.txt#68 2, M[3] = 3,espectA5" id="L335" cla5s="line" 5ame="L312"> 312   6h4ction476ill r:
 307   6 4pecif496mentenirdn"Documilito th6n bri69tation/memory-barriers.txt#L335" id="L252" cla5s="line" 5ame="L307"> 307   6 4ef="D486mentation/memory-barrier6.txt#69rriers.txt#L3espectatio#L276"TO0" catttttLOAD Xd="L335" cla5s="line" 5ame="L311"> 311   6 4ompon4n6s offirst load reall
 311   6h4ef="D4c6mentmrrierr
 287 (16 4 writ496atioe me-numbeive.  cer 6err
<69M[Q]tation/memory-barriers.tx catttttLOAD *C (ierss " d="L335" cla5s="line" 5ame="L311"> 311   6 4o hav4 6ny elerr
erceivo"oey  su6 migh6916" id="L216" cla5s="line" 5ame="L316"> 316   6h4ef="D4c6ment="DoassueB mighs bth6t
 351   6 4 CPU 496 meme me-numbeive.bankde6uence6918" id="L318" cla5s="line" 5ame="L338"> 338   6 4emory4s6stemodd-numbeive.bankdse6tdie,69 2, M[3] = 3,+L285" i+rriers.:riers.:ers.txt# cattttt:ers.txtid="L286" cla4s="line" 4ame="L351"> 351   6 4ccur 4n6the  is throold valu seq6ence=699ation/memory|/memory|/memory+L285" +                +L285" i+d="L301" cla5s="line" 5ame="L301"> 301   7h5ef="D5c7mentation/memory-barrier7.txt#700ation/memory|/memory|L285" 5" i| B=2ry|5" i-ryyyyyy5" 5" i| Y 5" i8ry|d="L301" cla5s="line" 5ame="L301"> 301   7h1ef="D5c7mentation/memory-barrier7.txt#701ation/memory|/memory|/m:mory+L285" +     \n/memory  +L285" i+d="L301" cla5s="line" 5ame="L301"> 301   7h2ef="D5c7m offirst load reall
 301   7h3ef="D5c7mentmrrierr
 301   7h4ef="D5c7mtioe me-numbeive.  cer 7arrie704ation/memory|/memory|/mewwwwwwwwwwwwwwwwo  |/memory :ers.txtid="L286" cla4s="line" 4ame="L351"> 351   7 5ata d507mentation/memory-barrier7.txt#705ation/memory|/memory|/memory+L285" +       |/memory :ers.txtid="L286" cla4s="line" 4ame="L351"> 351   7 6ata d507ment="DoassueB mighs bth7,,,as70tation/memory|/memory|/m:mory| C=#L276"T| i-ryyy|/memory :ers.txtimemory +L285" i+d="L301" cla5s="line" 5ame="L301"> 301   7 5 data507 = LOAD {*A, href="Docum7nt, h707ation/memory|/memory|/m:mory+L285" +   \   |/memory +L285" i+/memory|/memory|d="L301" cla5s="line" 5ame="L301"> 301   7 8 data507 temodd-numbeive.bankdse7M[1],708ation/memory|/memory|L285" 5" i| D=4ry|/memtxt#L285" i5" i| C 5" iL335"By|L285" 5" i| memory|d="L301" cla5s="line" 5ame="L301"> 301   7 9 data507 he  is throold valu seq7n/mem709ation/memory|/memory|/memory+L285" +       |/memory +L285" i+/memory|/memory|d="L301" cla5s="line" 5ame="L301"> 301   7 5oad w517AD *B,  X = < href="D7cume
7ntation/memory+L285" i+rriers.:riers.:ers.txt|/memory :ers.txtimemory |/memory|d="L301" cla5s="line" 5ame="L301"> 301   7 5!] No507AD *B,  STORP,  1ation/m7mory-71A-API-HOWTO0" cateeeeeeeeeeeeeeeLLLLLLLLLLLL|/memory :ers.txtimemory |/memory|d="L301" cla5s="line" 5ame="L301"> 301   7 2ef="D5c7 = LOAD {*A,,,,,        7   Q,7 Ptation/memory-barriers.txt#LeeeLLLLLLLLLLLL|/memory :ers.txtimemory |/-barit|d="L301" cla5s="line" 5ame="L301"> 301   7 5ef="D5c7*A = X; Y =             7   &l7;rrier would be required
gntateeeLLLLLLLLLLLL|/memory +L285" i+/memory|/memory|d="L301" cla5s="line" 5ame="L301"> 301   7 4ef="D5c7*A = Y = X;












7


, 7XM[Q]tation/memory-barriers.txeeeLLLLLLLLLLLL|/memory | X 5" i9 y|L285" 5" i| memory|d="L301" cla5s="line" 5ame="L301"> 301   7 5nly; 5c7mentation/memory-barrier7.txt#71Ptation/memory-barriers.txt#LLLLLLLLLLLLLLLL|/memory +L285" i+/memory|/memory|d="L301" cla5s="line" 5ame="L301"> 301   7 6ata d507mentation/memory-barrier7.txt#71rrier would be Makes su5" ie oumentas 5" 5" i L \   dddddddddddddddddory|/memory|d="L301" cla5s="line" 5ame="L301"> 301   7 5 data507mentThrfrriers should no7mally71*Qtation/memoryprior" icoma#L350".tf C        \emory +L285" i+/memory|/memory|d="L301" cla5s="line" 5ame="L301"> 301   7 8 data507ned rol rcu_ceivff tnce(7aiepi71Ptation/memory- kse-barrierxt#L iLLLLLLLLLLLLLL285" 5" i| B 5" i2 y|L285" 5" i| memory|d="L301" cla5s="line" 5ame="L301"> 301   7 9 data507g send load is i RCU dep7de"oe71*Qtation/memoryc5
 301   7 5onsid527mentenepreplaciarriond l7adefo72I/pci0" cation/meeeeeeeeeeeeeeeeLLLLLLLLLLLLLLLLLLLLL:ers.txtimemory +L285" i+d="L301" cla5s="line" 5ame="L301"> 301   7 5!] No507mentation/memory-barrier7.txt#7282" id="L282" cla5s="line" 5ame="L322"> 322   7 5btain517mentrol alsoa="Doc infor7atiat7243" id="L343" cla5s="line" 5ame="L353"> 353
 353
 351   7 5nly; 5c7y baCONTROL DEPENDENCIEn7tion/7216" id="L216" cla5s="line" 5ame="L316"> 316   7h5ef="D527poneument-
 307   7h5 data507mentation/memory-barrier7.txt#72f="Documentation/memory-barrory-barriers.txt#L252" iiiiiiiiid="L252" cla5s="line" 5ame="L307"> 307   7 8 data507ned Ay.  If the address 7ct"Do72Ptation/memory-baaaaa{tA5" 0,t355"9o}d="L349" class="line" name="L349"> 349   7 5ommit5i7g ses should normally  m7i tar729 (D, h 4)atiespectA=id="L335" cla5s="line" 5ame="L312"> 312   7 5!] No5e7thataodetation/memory-ba7riers73tation/memory-barriers.txt#L335" id="L252" cla5s="line" 5ame="L307"> 307   7 5!] No507mentation/memory-barrier7.txt#73rriers.txt#L3espectB=id="L252" cla5s="line" 5ame="L307"> 307   7 5btain517 = LOAD {*A,q,  &ata7ion/m73Ptation/memory-barriers.txt#LeeeeeeeeLOAD Bd="L252" cla5s="line" 5ame="L307"> 307   7 5ef="D5c7*A = X; Y = if (p)ation/7emory73rrier would be required
gntatttteeeeeLOAD Ad="L252" cla5s="line" 5ame="L307"> 307   7 4ef="D5c7*A = Y = X;








q,  7amp;b7385" id="L285" cla5s="line" 5ame="L325"> 325   7 5ubsec537AD *B,  X = <rrier wo7ld be7316" iW340" iation/meme" 5,y-barit#L27ding choos#L iL-barrs atrs.tx286" mony-barri sd="L285" cla5s="line" 5ame="L325"> 325   7 5ef="D527 = LOAD {*A,x  X*qtation7memor7-barri-ent umentas aDocuandommentat, hlhpit
 351   7 5!] No537mentation/memory-barrier7.txt#7318" id="L318" cla5s="line" 5ame="L338"> 338   7 5rite 537ill r:
 351   7h5ef="D537g ses should ncy is f="D7cucy.739ation/memory|/memory|/memory+L285" +                +L285" i+d="L301" cla5s="line" 5ame="L301"> 301   7h5ef="D547 = Latas
pte compipcumic7 thro740ation/memory|/memory|L285" 5" i| A=1ry|L285" memory5" 5" i| A 5" i0ry|d="L301" cla5s="line" 5ame="L301"> 301   7h5!] No507 = Lct"Documesetation/me7ory-b741ation/memory|/memory|/memory+L285" +      \n/memory +L285" i+d="L301" cla5s="line" 5ame="L301"> 301   7h5btain517mentation/memory-barrier7.txt#742ation/memory|/-barri|/mewwwwwwwwwwwwwwwwo  \mory5" 5" i| B 5" i9 y|d="L301" cla5s="line" 5ame="L301"> 301   7h5ef="D5c7 = LOAD {*A,q,  &ata7ion/m743ation/memory|/memory|/memory+L285" +        |/memory+L285" i+d="L301" cla5s="line" 5ame="L301"> 301   7 5OAD o547*A = X; Y = if (p)ation/7emory744ation/memory|/memory|L285" 5" i| B=2ry|5" emory|/memory:ers.txtid="L286" cla4s="line" 4ame="L351"> 351   7 5ll th547*A = X; Y =         q,  7amp;b745ation/memory|/memory|/memory+L285" +   \mory|/memory:ers.txti/memory+L285" i+d="L301" cla5s="line" 5ame="L301"> 301   7 5ef="D527AD *B,  X = <ld norma7ly 
g7tation/memory-+L285" i+rriers.:riers.:ers.\   |/memory+L285" i+/memory|/memory|d="L301" cla5s="line" 5ame="L301"> 301   7 5!] No537 = LOAD {*A,x  X*qtation7memor74*Qtation/memory-barriers.txt# cattttttttttt#L285" i 5" i| B 5" i2 y|L285" 5" i| memory|d="L301" cla5s="line" 5ame="L301"> 301   7 5rite 537mentation/memory-barrier7.txt#74Ptation/memory-baaaaaaaaaaaaaaaaaaaaaaaaaaaaa|/memory+L285" i+/memory|/-barit|d="L301" cla5s="line" 5ame="L301"> 301   7 5ave a547mentation/memory-barrier7.txt#74*Qtation/memory-baaaaaaaaaaaaaaaaaaaaaaaaaaaa|/memory| A 5" i0ry|L285" 5" i| memory|d="L301" cla5s="line" 5ame="L301"> 301   7h5ef="D5c7mentg&quBDocume PAIRINGa7ion/m75I/pci0" cation/meeeeeeeeeeeeeeeeLLLLLLLLLLLLL|/memory+L285" i+/memory|/memory|d="L301" cla5s="line" 5ame="L301"> 301   7 5ead m5c7mentment-
 301   7 5or th557mentation/memory-barrier7.txt#75Ptation/memory-barriers.txt#LeeeLLLLLLLLLLLL  \n/memo:ers.txtid="L286" cla4s="line" 4ame="L351"> 351   7 5 read547 = LWnrnDda _e cos;
 301   7 5OAD o547; Y  305 (2) 5at5tru7t the75M[Q]tation/memory-barriers.txeeeLLLLLLLLLLLLLLLL85" 5" i| A 5" i1ry|d="L301" cla5s="line" 5ame="L301"> 301   7 5ll th547AD *A,  STORB,  4tation/7emory75Ptation/memory-barriers.txt#LLLLLLLLLLLLLLLLLLLLLLLLL+L285" i+d="L301" cla5s="line" 5ame="L301"> 301   7h4ef="D457AD *B,  X = < href="D7cume
75rrier would be required
gntattttttttttttttttttttttttt:ers.txtid="L286" cla4s="line" 4ame="L351"> 351   7h5ef="D547AD *B,  STORP,  &tat7on/me7518" id="L318" cla5s="line" 5ame="L338"> 338   7h5rite 537*A = X; Y =             7   Q,7589" id="L289" cla4s="line" 4ame="L279"> 279int7 5ave a547*A = Y = X;












7


, 759atioIf, howevd t#Le.hredtation/mw-barceins ,rs;
 279int7 4 gene4c7mentation/memory-barrier7.txt#760atioriertxt#Aeony-bar2id="L286" cla4s="line" 4ame="L351"> 351   7 4perat4o7s spT per dependenclre a7riers7682" id="L282" cla5s="line" 5ame="L322"> 322   7 5or th557and  operati, Q,hat  any7barri762ation/memory-barriers.txt#L222222222-barid="L252" cla5s="line" 5ame="L307"> 307   7 5 read547mentation/memory-barrier7.txt#763ation/memoryion/memory-barrory-barriers.txt#L252" iiiiiiiiid="L252" cla5s="line" 5ame="L307"> 307   7 5OAD o547; Y = *A;
 349   7 4ee th457; Y = *A;
 312   7 4ef="D457mentation/memory-barrier7.txt#76tation/memory-barriers.txt#L335" id="L335" cla4s="line" 4ame="L357"> 357
 307   7 5rite 537e otlrede compitnces:
 307   7 5ave a547mentation/memory-barrier7.txt#76*Qtation/memory-bbbbbbbbbbbbbbbbbbbbb-bariers.txt#L335" id="L335" cla5s="line" 5ame="L347"> 347
 307   7r4 barr477mentation/memory-barrier7.txt#7782" id="L282" cla5s="line" 5ame="L322"> 322   7h5or th557mentWhilsoblem fa hrbarn7likgs77Ptatiding barrf="Documentation impos49"by3-barrLbee obeL-barrs ad ory-baratioy3-bad="L282" cla5s="line" 5ame="L322"> 322   7h5 read547mentisn depet,Documenif 7whavi77rrier2id="L286" cla4s="line" 4ame="L351"> 351   7h5OAD o547mentAlphantation/memory-7arrie7785" id="L285" cla5s="line" 5ame="L325"> 325   7u4e a v477mentation/memory-barrier7.txt#775ry-barriers.+L285" i+rriers.:riers.:eeeeeeeeeeeLLLLL:ers.txtid="L286" cla4s="line" 4ame="L351"> 351   7u4ef="D457s spro da _epeothenify b7rrier77tation/memory|/memory|/memory+L285" +eeeeeeeeeeeLLLLL+L285" i+d="L301" cla5s="line" 5ame="L301"> 301   7c4 pred4c7ion aetwdento then it%a hro777ation/memory|/memory|L285" 5" i| A=1ry|L285" memory5" 5" i| A 5" i0ry|d="L301" cla5s="line" 5ame="L301"> 301   7c4>    4t7mentation/memory-barrier7.txt#778ation/memory|/memory|/memory+L285" +memory\n/memory +L285" i+d="L301" cla5s="line" 5ame="L301"> 301   7r4ction477 = LOAD {*A,as c1AD {*A,7,,,as779ation/memory|/-barri|/mewwwwwwwwwwwwwwwwo  \mory5" 5" i| B 5" i9 y|d="L301" cla5s="line" 5ame="L301"> 301   7h4ef="D487 = LOAD {*A, href="Docum7nt, h780ation/memory|/memory|/memory+L285" +eeeeeeee|/memory+L285" i+d="L301" cla5s="line" 5ame="L301"> 301   7h4ef="D487; Y = *A;
 351   7E4IES O487AD *A,  STORB,  4tation/7emory782ation/memory|/memory|/memory+L285" +/me\mory|/memory:ers.txti/memory+L285" i+d="L301" cla5s="line" 5ame="L301"> 301   7h4he ot467AD *B,  X = < href="D7cume
783ry-barriers.+L285" i+rriers.:riers.:eeee\   |/memory+L285" i+/memory|/memory|d="L301" cla5s="line" 5ame="L301"> 301   7-4nforc477AD *B,  STORP,  &tat7on/me78M[Q]tation/memory-barriers.txeeeLLLLLLLLLLt#L285" i 5" i| B 5" i2 y|L285" 5" i| memory|d="L301" cla5s="line" 5ame="L301"> 301   7r4 barr487*A = X; Y =             7   Q,78Ptation/memory-barriers.txt#LLLLLLLLLLLLLLLLL|/memory+L285" i+/memory|/-barit|d="L301" cla5s="line" 5ame="L301"> 301   7h4ef="D487*A = X; Y =             7   &l78rrier would be required
gntattttttttttttttttt|/memory:ers.txti/memory| memory|d="L301" cla5s="line" 5ame="L301"> 301   7r4 pred4c7*A = Y = X;












7


, 7X*Qtation/memory-barried
gntattttttttttttttttt|/memory:ers.txti/memory| memory|d="L301" cla5s="line" 5ame="L301"> 301   7r4>    4t7mentation/memory-barrier7.txt#78Ptation/memory-Ae=ituer moda 301   7r4ction477ill r:
 301   7 4pecif497mentenirdn"Documilito th7n bri79I/pci0" cation/prior" icoma#L350agetxt#L        85" 5" i| A 5" i1ry|L285" 5" i| memory|d="L301" cla5s="line" 5ame="L301"> 301   7 4ef="D487mentation/memory-barrier7.txt#79A-API-HOWTO0" cceins ,barrierxt#L iL-baritttttttttttt+L285" i+/memory| memory|d="L301" cla5s="line" 5ame="L301"> 301   7 4IES O487s offirst load reall
 301   7h4ef="D4c7mentmrrierr
 294   7 4 writ497atioe me-numbeive.  cer 7err
<7985" id="L285" cla5s="line" 5ame="L325"> 325   7 4o hav4 7ny elerr
erceivo"oey  su7 migh7916" iTo ee ustrat
 279int7h4ef="D4c7ment="DoassueB mighs bth7t
 351   7 4 CPU 497 meme me-numbeive.bankde7uence7918" id="L318" cla5s="line" 5ame="L338"> 338   7 4emory4s7stemodd-numbeive.bankdse7tdie,79 2, M[3] = 3,-barriers.txt#L222222222-barid="L252" cla5s="line" 5ame="L307"> 307   7 4ccur 4n7the  is throold valu seq7ence=799ation/memoryion/memory-barrory-barriers.txt#L252" iiiiiiiiid="L252" cla5s="line" 5ame="L307"> 307   8h5ef="D5c8mentation/memory-barrier8.txt#80I/pci0" cation/meeeee{tA5" 0,t355"9o}d="L349" class="line" name="L349"> 349   8h1ef="D5c8mentation/memory-barrier8.txt#80rriers.txt#L3espectA=id="L335" cla5s="line" 5ame="L312"> 312   8h2ef="D5c8m offirst load reall
 357
 307   8h4ef="D5c8mtioe me-numbeive.  cer 8arrie80M[Q]tation/memory-barriers.tx catttttLOAD Bd="L252" cla5s="line" 5ame="L307"> 307   8 5ata d508mentation/memory-barrier8.txt#80Ptation/memory-barriers.txt#LLLLLLLLLLOAD A [fence riertxt#A]d="L252" cla5s="line" 5ame="L307"> 307   8 6ata d508ment="DoassueB mighs bth8,,,as80rrier would be required
gntattttttttt-bariers.txt#L335" id="L335" cla5s="line" 5ame="L347"> 347
 307   8 8 data508 temodd-numbeive.bankdse8M[1],8089" id="L289" cla4s="line" 4ame="L279"> 279int8 9 data508 he  is throold valu seq8n/mem809atioEL36540" /metxt#two/riers.xt#AebothoicfteLts.txt#L36riertxt#B,xtcuyt#L27bothd="L289" cla4s="line" 4ame="L279"> 279int8 5oad w518AD *B,  X = < href="D8cume
8ntatiocent up wiie dimen0" i value id="L286" cla4s="line" 4ame="L351"> 351   8 5!] No508AD *B,  STORP,  1ation/m8mory-8182" id="L282" cla5s="line" 5ame="L322"> 322   8 2ef="D5c8 = LOAD {*A,,,,,        8   Q,812ation/memory+L285" i+rriers.:riers.:ers.txt# cattttt:ers.txtid="L286" cla4s="line" 4ame="L351"> 351   8 5ef="D5c8*A = X; Y =             8   &l813ation/memory|/memory|/memory+L285" +                +L285" i+d="L286" cla4s="line" 4ame="L351"> 351   8 4ef="D5c8*A = Y = X;












8


, 814ation/memory|/memory|L285" 5" i| A=1ry|L285" memory5" 5" i| A 5" i0ry|d="L301" cla5s="line" 5ame="L301"> 301   8 5nly; 5c8mentation/memory-barrier8.txt#815ation/memory|/memory|/memory+L285" +      \n/memory +L285" i+d="L301" cla5s="line" 5ame="L301"> 301   8 6ata d508mentation/memory-barrier8.txt#81tation/memory|/-barri|/mewwwwwwwwwwwwwwwwo  \mory5" 5" i| B 5" i9 y|d="L301" cla5s="line" 5ame="L301"> 301   8 5 data508mentThrfrriers should no8mally817ation/memory|/memory|/memory+L285" +        |/memory+L285" i+d="L301" cla5s="line" 5ame="L301"> 301   8 8 data508ned rol rcu_ceivff tnce(8aiepi818ation/memory|/memory|L285" 5" i| B=2ry|5" emory|/memory:ers.txtid="L286" cla4s="line" 4ame="L351"> 351   8 9 data508g send load is i RCU dep8de"oe819ation/memory|/memory|/memory+L285" +   \mory|/memory:ers.txti/memory+L285" i+d="L301" cla5s="line" 5ame="L301"> 301   8 5onsid528mentenepreplaciarriond l8adefo82tation/memory+L285" i+rriers.:riers.:ers.\   |/memory+L285" i+/memory|/memory|d="L301" cla5s="line" 5ame="L301"> 301   8 5!] No508mentation/memory-barrier8.txt#82A-API-HOWTO0" cateeeeeeeeeeeeeeeLLLLLLLLLLt#L285" i 5" i| B 5" i2 y|L285" 5" i| memory|d="L301" cla5s="line" 5ame="L301"> 301   8 5btain518mentrol alsoa="Doc infor8atiat82Ptation/memory-barriers.txt#LeeeLLLLLLLLLLLL |/memory+L285" i+/memory|/-barit|d="L301" cla5s="line" 5ame="L301"> 301   8 5ef="D5c8mentation/memory-barrier8.txt#82rrier would be required
gntateeeLLLLLLLLLLLLL|/memory:ers.txti/memory| memory|d="L301" cla5s="line" 5ame="L301"> 301   8 4ef="D5c8mentation/memory-barrier8.txt#82M[Q]tation/memory-barriers.txeeeLLLLLLLLLLLLL|/memory:ers.txti/memory| memory|d="L301" cla5s="line" 5ame="L301"> 301   8 5nly; 5c8y baCONTROL DEPENDENCIEn8tion/82Ptation/memory-barriers.txt#LLLLLLLLLLLLLLLLL|/memory+L285" i+/memory|/memory|d="L301" cla5s="line" 5ame="L301"> 301   8 6ata d508poneument-
 301   8 5 data508mentation/memory-barrier8.txt#82*Qtation/memory-barried
gntattttttttttttttttt|/memory+L285" i+/memory|/memory|d="L301" cla5s="line" 5ame="L301"> 301   8 8 data508ned Ay.  If the address 8ct"Do82Ptation/memory-Ae=ituer moda 301   8 5ommit5i8g ses should normally  m8i tar82*Qtation/memorytation/mcausensdesaumentas      \n/mem+L285" i+/memory| memory|d="L301" cla5s="line" 5ame="L301"> 301   8 5!] No5e8thataodetation/memory-ba8riers83I/pci0" cation/prior" icoma#L350agetxt#L        85" 5" i| A 5" i1ry|L285" 5" i| 2ndory|d="L301" cla5s="line" 5ame="L301"> 301   8 5!] No508mentation/memory-barrier8.txt#83A-API-HOWTO0" cceins ,barrierxt#L iL-baritttttttttttt+L285" i+/memory| memory|d="L301" cla5s="line" 5ame="L301"> 301   8 5btain518 = LOAD {*A,q,  &ata8ion/m83Ptation/memory-barriers.txt#Leeeeeeeeeeeeeeeeeeeeeeee:ers.txti/memory+L285" i+d="L301" cla5s="line" 5ame="L301"> 301   8 5ef="D5c8*A = X; Y = if (p)ation/8emory8394" id="L294" cla3s="line" 3ame="L294"> 294   8 4ef="D5c8*A = Y = X;








q,  8amp;b8385" id="L285" cla5s="line" 5ame="L325"> 325   8 5ubsec538AD *B,  X = <rrier wo8ld be8316" iB iattt#L27be tive=itr acatioL iLA from/-barribecent m-barrierxt#L i2-barid="L252" cla5s="line" 5ame="L307"> 307   8 5ef="D528 = LOAD {*A,x  X*qtation8memor8-barribfore
 351   8 5!] No538mentation/memory-barrier8.txt#8318" id="L318" cla5s="line" 5ame="L338"> 338   8 5rite 538ill r:
 351   8h5ef="D538g ses should ncy is f="D8cucy.839ation/memory|/memory|/memory+L285" +                +L285" i+d="L301" cla5s="line" 5ame="L301"> 301   8h5ef="D548 = Latas
pte compipcumic8 thro840ation/memory|/memory|L285" 5" i| A=1ry|L285" memory5" 5" i| A 5" i0ry|d="L301" cla5s="line" 5ame="L301"> 301   8h5!] No508 = Lct"Documesetation/me8ory-b841ation/memory|/memory|/memory+L285" +      \n/memory +L285" i+d="L301" cla5s="line" 5ame="L301"> 301   8h5btain518mentation/memory-barrier8.txt#842ation/memory|/-barri|/mewwwwwwwwwwwwwwwwo  \mory5" 5" i| B 5" i9 y|d="L301" cla5s="line" 5ame="L301"> 301   8h5ef="D5c8 = LOAD {*A,q,  &ata8ion/m843ation/memory|/memory|/memory+L285" +        |/memory+L285" i+d="L301" cla5s="line" 5ame="L301"> 301   8 5OAD o548*A = X; Y = if (p)ation/8emory844ation/memory|/memory|L285" 5" i| B=2ry|5" emory|/memory:ers.txtid="L286" cla4s="line" 4ame="L351"> 351   8 5ll th548*A = X; Y =         q,  8amp;b845ation/memory|/memory|/memory+L285" +   \mory|/memory:ers.txti/memory+L285" i+d="L301" cla5s="line" 5ame="L301"> 301   8 5ef="D528AD *B,  X = <ld norma8ly 
g8tation/memory-+L285" i+rriers.:riers.:ers.\   |/memory+L285" i+/memory|/memory|d="L301" cla5s="line" 5ame="L301"> 301   8 5!] No538 = LOAD {*A,x  X*qtation8memor84*Qtation/memory-barriers.txt# cattttttttttt#L285" i 5" i| B 5" i2 y|L285" 5" i| memory|d="L301" cla5s="line" 5ame="L301"> 301   8 5rite 538mentation/memory-barrier8.txt#84Ptation/memory-baaaaaaaaaaaaaaaaaaaaaaaaaaaaa|/memory+L285" i+/memory|/-barit|d="L301" cla5s="line" 5ame="L301"> 301   8 5ave a548mentation/memory-barrier8.txt#84*Qtation/memory-baaaaaaaaaaaaaaaaaaaaaaaaaaaa|/memory:ers.txti/memory| memory|d="L301" cla5s="line" 5ame="L301"> 301   8h5ef="D5c8mentg&quBDocume PAIRINGa8ion/m85I/pci0" cation/meeeeeeeeeeeeeeeeLLLLLLLLLLLLL \n/memo:ers.txti/memory| memory|d="L301" cla5s="line" 5ame="L301"> 301   8h5!] No508mentment-
 301   8 5or th558mentation/memory-barrier8.txt#85Ptation/memory-barriers.txt#LeeeLLLLLLLLLLLL    85" 5" i| A 5" i1ry|L285" 5" i| 1ce ry|d="L301" cla5s="line" 5ame="L301"> 301   8 5 read548 = LWnrnDda _e cos;
 301   8 5OAD o548; Y  305 (2) 5at5tru8t the85M[Q]tation/memory-barriers.txeeeLLLLLLLLLLLLLLLL rrrrrrrrrrrrrrrrrory| memory|d="L301" cla5s="line" 5ame="L301"> 301   8 5ll th548AD *A,  STORB,  4tation/8emory85Ptation/memory-barriers.txt#LLLLLLLLLLLLLLLLLLLLLLLLL+L285" i+/memory| memory|d="L301" cla5s="line" 5ame="L301"> 301   8 5ef="D528AD *B,  X = < href="D8cume
85rrier would be required
gntattttttttttttttttttttttttt| A 5" i1ry|L285" 5" i| 2ndory|d="L301" cla5s="line" 5ame="L301"> 301   8h5ef="D548AD *B,  STORP,  &tat8on/me85*Qtation/memory-barried
gntatttttttttttttttttLLLLLLLL+L285" i+/memory| memory|d="L301" cla5s="line" 5ame="L301"> 301   8 5rite 538*A = X; Y =             8   Q,85Ptation/memory-baaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa:ers.txti/memory+L285" i+d="L301" cla5s="line" 5ame="L301"> 301   8 5ave a548*A = Y = X;












8


, 859atiod="L301" cla5s="line" 5ame="L301"> 301   8 4 gene4c8mentation/memory-barrier8.txt#860atiod="L301" cla5s="line" 5ame="L301"> 301   8 5!] No508s spT per dependenclre a8riers8682" iTon/guaranteems
,tive=itr sry-ba riertbee oalways cent up wiie A ==rri fbeivd="L289" cla4s="line" 4ame="L279"> 279int8 5or th558and  operati, Q,hat  any8barri862atioriertxt#B cant up wiie B ==r2.  No such/guaranteemexists foxt#L36fence riertxtd="L289" cla4s="line" 4ame="L279"> 279int8 5 read548mentation/memory-barrier8.txt#863atioA;,tive=#L27cent up wiie eiiertaA ==r0 otaA ==r1id="L364" class="line" name="L286"> 286
 325   8 4ee th458; Y = *A;
 316   8 4ef="D458mentation/memory-barrier8.txt#86tatioREAD MEMORY BARRIERS VStLOAD SPECULATIONd="L216" cla5s="line" 5ame="L316"> 316   8 5ef="D548emorBut!,,as c2 depend l8ads i86f="Do----------------------------------------d="L216" cla5s="line" 5ame="L316"> 316   8 5rite 538e otlrede compitnces:
 279int8 5ave a548mentation/memory-barrier8.txt#86*QtatMany3-bas specultioLwiie riers:,tive=s
,tiey sre tive=itrytbee oneedL i2riertasd="L285" cla5s="line" 5ame="L325"> 325   8h4ef="D478; Y = *A;
 325   8h5!] No508mentation/memory-barrier8.txt#8782" ioiertariers, numbso dot#L36riertin adv#L34w-tx286540" /metxty ha286'tmNtauallyd="L285" cla5s="line" 5ame="L325"> 325   8h5or th558mentWhilsoblem fa hrbarn8likgs87Ptatigot  icomve= moda 279int8h5 read548mentisn depet,Documenif 8whavi87rrierNtaual6riertinstruce" 5m iL-ot"liiallymtomplete immediate iibecause barr-bad="L282" cla5s="line" 5ame="L322"> 322   8h5OAD o548mentAlphantation/memory-8arrie8785" ial.hrey hasbeiv valuem iLhnumid="L364" class="line" name="L286"> 286
 316   8u4ef="D458s spro da _epeothenify b8rrier87tatioIe=#L27turn " iative=itr -bardid6'tmNtauallyoneedL iv valuem-m-bahapsibecause ad="L216" cla5s="line" 5ame="L316"> 316   8u5ef="D548ion aetwdento then it&a hro877atiobranch/cir5s=286"embeiveriert- 316   8u5rite 538mentation/memory-barrier8.txt#878atiocache ittfoxtltior useid="L364" class="line" name="L286"> 286
 301   8h4ef="D488 = LOAD {*A, href="Docum8nt, h880ation/memoryid="L286" cla4s="line" 4ame="L351"> 351   8h4ef="D488; Y = *A;
 282VAR8E4IES O488AD *A,  STORB,  4tation/8emory882ation/memory-barriers.txt#L222222222-barid="L252" cla5s="line" 5ame="L307"> 307   8h4he ot468AD *B,  X = < href="D8cume
883ation/memoryion/memory-barrory-barriers.txt#L252" iiiiiiiiid="L252" cla5s="line" 5ame="L307"> 307   8-4nforc478AD *B,  STORP,  &tat8on/me88M[Q]tation/memory-barriers.txeeeLLLLLLOAD Bd="L252" cla5s="line" 5ame="L307"> 307   8r4 barr488*A = X; Y =             8   Q,88Ptation/memory-barriers.txt#LLLLLLLLLDIVIDE#LLLLLLLLL} Divmoreinstruce" 5s generallyd="L285" cla5s="line" 5ame="L325"> 325   8h4ef="D488*A = X; Y =             8   &l88rrier would be required
gntatttttttttDIVIDE#LLLLLLLLL} take a rion #int  iL-bafoxmd="L285" cla5s="line" 5ame="L325"> 325   8h5ef="D548*A = Y = X;












8


, 8X*Qtation/memory-barried
gntatttttttttLOAD Ad="L252" cla5s="line" 5ame="L307"> 307   8r4>    4t8mentation/memory-barrier8.txt#8889" id="L289" cla4s="line" 4ame="L279"> 279int8r4ction478ill r:
 351   8 4pecif498mentenirdn"Documilito th8n bri890atiod="L301" cla5s="line" 5ame="L301"> 301   8 4ef="D488mentation/memory-barrier8.txt#89A-API-HOWTO0" ccccccccccccccccccccccccccccccccccccccc:ers.txti/memory+L285" i+d="L301" cla5s="line" 5ame="L301"> 301   8 4IES O488s offirst load reall
 301   8h4ef="D4c8mentmrrierr
 301   8 4 writ498atioe me-numbeive.  cer 8err
<89M[Q]tation/memory-barriers.tx catttttLLLLLLL         +L285" i+/memory| -barit|d="L301" cla5s="line" 5ame="L301"> 301   8 4o hav4 8ny elerr
erceivo"oey  su8 migh89Ptation/memory-barriers.txt#LLLLLLLLLLLLLLLLLLLLLLLLL:ers.txtiDIVIDE#| memory|d="L301" cla5s="line" 5ame="L301"> 301   8 4ef="D488ment="DoassueB mighs bth8t
 301   8h5ef="D548 meme me-numbeive.bankde8uence89*Qtation/memoTtr -barbeion busy doxt#Lt 5" 5" i L  y5" 5" i| A 5" i0ry|~~~~ory| memory|d="L301" cla5s="line" 5ame="L301"> 301   8h4>    4t8stemodd-numbeive.bankdse8tdie,89 2, M[3] = 3,divms" 5mspecultio mony iv ttttttttttttt+L285" i+/me~ory| memory|d="L301" cla5s="line" 5ame="L301"> 301   8h4ction478the  is throold valu seq8ence=899ation/memoryLOAD xt#Ad
gntattttttttttttttttttttttttt:ers.txti/me~ory| memory|d="L301" cla5s="line" 5ame="L301"> 301   9h5ef="D5c9mentation/memory-barrier9.txt#90I/pci0" cation/meeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee:ers.txtiDIVIDE#| memory|d="L301" cla5s="line" 5ame="L301"> 301   9h1ef="D5c9mentation/memory-barrier9.txt#90A-API-HOWTO0" ccccccccccccccccccccccccccccccccccccccc:ers.txti/me~ory| memory|d="L301" cla5s="line" 5ame="L301"> 301   9h2ef="D5c9m offirst load reall
 301   9h3ef="D5c9mentmrrierr
 301   9h4ef="D5c9mtioe me-numbeive.  cer 9arrie90M[Q]tation/meLOAD wiie immediateaumentacccccccccccccc:ers.txti/meeeee+L285" i+d="L301" cla5s="line" 5ame="L301"> 301   9 5ata d509mentation/memory-barrier9.txt#9016" id="L216" cla5s="line" 5ame="L316"> 316   9 6ata d509ment="DoassueB mighs bth9,,,as90rrierd="L216" cla5s="line" 5ame="L316"> 316   9 7ata d509mmeme me-numbeive.bankde9nt, h90*QtatPlacxt#Lt .hredtation/moxta demory-barriers.txt#L33tjust bfore
 316   9 8ata d509mtemodd-numbeive.bankdse9M[1],9089" irierid="L286" cla4s="line" 4ame="L351"> 351   9 9 data509 he  is throold valu seq9n/mem909atiod="L301" cla5s="line" 5ame="L301"> 301   9 5oad w519AD *B,  X = < href="D9cume
9ntation/memory-barriers.txt#L222222222-barid="L252" cla5s="line" 5ame="L307"> 307   9 5!] No509AD *B,  STORP,  1ation/m9mory-91A-API-HOWTO0"ion/memory-barrory-barriers.txt#L252" iiiiiiiiid="L252" cla5s="line" 5ame="L307"> 307   9 2ef="D5c9 = LOAD {*A,,,,,        9   Q,9 Ptation/memory-barriers.txt#LeeeLLLLLLOAD Bd="L252" cla5s="line" 5ame="L307"> 307   9 5ef="D5c9*A = X; Y =             9   &l9;rrier would be required
gntateeeLLLLLDIVIDEd="L252" cla5s="line" 5ame="L307"> 307   9 4ef="D5c9*A = Y = X;












9


, 9XM[Q]tation/memory-barriers.txeeeLLLLLDIVIDEd="L252" cla5s="line" 5ame="L307"> 307   9 5ata d509mentation/memory-barrier9.txt#91Ptation/memory-barriers.txt#LLLLLLLLL-bariers.txt#L335" id="L335" cla5s="line" 5ame="L347"> 347
 307   9 5 data509mentThrfrriers should no9mally9118" id="L318" cla5s="line" 5ame="L338"> 338   9 8 data509ned rol rcu_ceivff tnce(9aiepi918atiobee oore34wany3valuemspecultis aDocobtaeB d ceins rec/memory d ceia5mext"lid="L318" cla5s="line" 5ame="L338"> 338   9 9 data509g send load is i RCU dep9de"oe919atioy-barrietmony iv typetxt#txt#L33tused.  Ifbeive
 338   9 5onsid529mentenepreplaciarriond l9adefo92tatiospecultiod/me="L3 locne" 5, ding barrspecultiod/valuembee ojust bftusedid="L286" cla4s="line" 4ame="L351"> 351   9 5!] No509mentation/memory-barrier9.txt#9282" id="L282" cla5s="line" 5ame="L322"> 322   9 5btain519mentrol alsoa="Doc infor9atiat92Ptation/memory-barriers.txt#LeeeLLLLLLLLLLLL         :ers.txti/meeeee+L285" i+d="L301" cla5s="line" 5ame="L301"> 301   9 5ef="D5c9mentation/memory-barrier9.txt#92rrier would be required
gntateeeLLLLLLLLLLLLLLLLLLLLL+L285" i+/memory| memory|d="L301" cla5s="line" 5ame="L301"> 301   9 4ef="D5c9mentation/memory-barrier9.txt#92M[Q]tation/memory-barriers.txeeeLLLLLLLLLLLLLLLLL i 5" i| B 5" i2 y|L285" 5" i| memory|d="L301" cla5s="line" 5ame="L301"> 301   9 5nly; 5c9y baCONTROL DEPENDENCIEn9tion/92Ptation/memory-barriers.txt#LLLLLLLLLLLLLLLLLLLLLLLLL+L285" i+/memory| -barit|d="L301" cla5s="line" 5ame="L301"> 301   9 6ata d509poneument-
 301   9 5 data509mentation/memory-barrier9.txt#92*Qtation/memory-barried
gntatttttttttttttttttLLLLLLLL+L285" i+/memory| memory|d="L301" cla5s="line" 5ame="L301"> 301   9 8 data509ned Ay.  If the address 9ct"Do92Ptation/memorTtr -barbeion busy doxt#Lt 5" 5" i L  y5" 5" i| A 5" i0ry|~~~~ory| memory|d="L301" cla5s="line" 5ame="L301"> 301   9 5ommit5i9g ses should normally  m9i tar92*Qtation/memodivms" 5mspecultio mony iv ttttttttttttt+L285" i+/me~ory| memory|d="L301" cla5s="line" 5ame="L301"> 301   9 5!] No5e9thataodetation/memory-ba9riers93I/pci0" catioLOAD xt#Ad
gntattttttttttttttttttttttttt:ers.txti/me~ory| memory|d="L301" cla5s="line" 5ame="L301"> 301   9 5!] No509mentation/memory-barrier9.txt#93A-API-HOWTO0" ccccccccccccccccccccccccccccccccccccccc:ers.txtiDIVIDE#| memory|d="L301" cla5s="line" 5ame="L301"> 301   9 5btain519 = LOAD {*A,q,  &ata9ion/m93Ptation/memory-barriers.txt#Leeeeeeeeeeeeeeeeeeeeeeee:ers.txti/me~ory| memory|d="L301" cla5s="line" 5ame="L301"> 301   9 5ef="D5c9*A = X; Y = if (p)ation/9emory93rrier would be required
gntatttteeeeeeeeeeeeeeeeeeeee:ers.txti/me~ory| memory|d="L301" cla5s="line" 5ame="L301"> 301   9 4ef="D5c9*A = Y = X;








q,  9amp;b93M[Q]tation/memory-barriers.txeeeLLLLLLLLLLLLLLLL rrrrrrrrrrrrrrrr~ory| memory|d="L301" cla5s="line" 5ame="L301"> 301   9 5nly; 5c9AD *B,  X = <rrier wo9ld be93Ptation/memory-barriers.txt#LLLLLLLLLLLLLLLLLLLLLLLLL:ers.txti/me~ory| memory|d="L301" cla5s="line" 5ame="L301"> 301   9 6ata d509 = LOAD {*A,x  X*qtation9memor93rrier would be required
gntattttttttttttttttttttttttt:ers.txti me~" 5" i| memory|d="L301" cla5s="line" 5ame="L301"> 301   9 5!] No539mentation/memory-barrier9.txt#93*Qtation/memory-barried
gntatttttttttttttttttLLLLLLLL:ers.txti/memory| memory|d="L301" cla5s="line" 5ame="L301"> 301   9 5rite 539ill r:
 301   9h5ef="D539g ses should ncy is f="D9cucy.939atiod="L301" cla5s="line" 5ame="L301"> 301   9h5ef="D549 = Latas
pte compipcumic9 thro940atiod="L301" cla5s="line" 5ame="L301"> 301   9h5!] No509 = Lct"Documesetation/me9ory-b941atiob iatfbeive
 301   9h5btain519mentation/memory-barrier9.txt#94Ptatidinmspecultis 5mbee obeLc#L34ll d andL iv valuemrerieredid="L286" cla4s="line" 4ame="L351"> 351   9h5ef="D5c9 = LOAD {*A,q,  &ata9ion/m9494" id="L294" cla3s="line" 3ame="L294"> 294   9 5OAD o549*A = X; Y = if (p)ation/9emory94M[Q]tation/memory-barriers.tx catttttLLLLLLL         :ers.txti/memory+L285" i+d="L301" cla5s="line" 5ame="L301"> 301   9 5ll th549*A = X; Y =         q,  9amp;b94Ptation/memory-barriers.txt#LLLLLLLLLLLLLLLLLLLLLLLLL+L285" i+/memory| memory|d="L301" cla5s="line" 5ame="L301"> 301   9 5ef="D529AD *B,  X = <ld norma9ly 
g94rrier would be required
gntattttttttttttttttttttt i 5" i| B 5" i2 y|L285" 5" i| memory|d="L301" cla5s="line" 5ame="L301"> 301   9 5!] No539 = LOAD {*A,x  X*qtation9memor94*Qtation/memory-barriers.txt# cattttttttttLLLLLLLLLLL+L285" i+/memory| -barit|d="L301" cla5s="line" 5ame="L301"> 301   9 5rite 539mentation/memory-barrier9.txt#94Ptation/memory-baaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa:ers.txtiDIVIDE#| memory|d="L301" cla5s="line" 5ame="L301"> 301   9 5ave a549mentation/memory-barrier9.txt#94*Qtation/memory-baaaaaaaaaaaaaaaaaaaaaaaaaaaaLLLLLLLL+L285" i+/memory| memory|d="L301" cla5s="line" 5ame="L301"> 301   9h5ef="D5c9mentg&quBDocume PAIRINGa9ion/m95I/pci0" catioTtr -barbeion busy doxt#Lt 5" 5" i L  y5" 5" i| A 5" i0ry|~~~~ory| memory|d="L301" cla5s="line" 5ame="L301"> 301   9h5!] No509mentment-
 301   9 5or th559mentation/memory-barrier9.txt#95Ptation/memorLOAD xt#Ad
gntattttttttttttttttttttttttt:ers.txti/me~ory| memory|d="L301" cla5s="line" 5ame="L301"> 301   9 5 read549 = LWnrnDda _e cos;
 301   9 5OAD o549; Y  305 (2) 5at5tru9t the95M[Q]tation/memory-barriers.txeeeLLLLLLLLLLLLLLLL tttt:ers.txti/me~ory| memory|d="L301" cla5s="line" 5ame="L301"> 301   9 5ll th549AD *A,  STORB,  4tation/9emory95Ptation/memory-barriers.txt#LLLLLLLLLLLLLLLLLLLLLLLLL:ers.txti/me~ory| memory|d="L301" cla5s="line" 5ame="L301"> 301   9 5ef="D529AD *B,  X = < href="D9cume
95rrier would be required
gntatttttttttttttttttttttrrrrrrrrrrrrrrrrrory| memory|d="L301" cla5s="line" 5ame="L301"> 301   9h5ef="D549AD *B,  STORP,  &tat9on/me95*Qtation/memory-barried
gntatttttttttttttttttLLLLLLLL+L285" i+/memory| memory|d="L301" cla5s="line" 5ame="L301"> 301   9 5rite 539*A = X; Y =             9   Q,95Ptation/memorTtr specultis 5misrdiscarded 5" 5" i L -" 5" i| A 5" i1ry|L285" 5" i| memory|d="L301" cla5s="line" 5ame="L301"> 301   9 5ave a549*A = Y = X;












9


, 95*Qtation/memoandLa5macatiod/valuemistttttttttLLLLLLLL+L285" i+/memory| memory|d="L301" cla5s="line" 5ame="L301"> 301   9 4 gene4c9mentation/memory-barrier9.txt#96I/pci0" catioret 30 ad                               :ers.txti/memory+L285" i+d="L301" cla5s="line" 5ame="L301"> 301   9 5!] No509s spT per dependenclre a9riers9682" id="L282" cla5s="line" 5ame="L322"> 322   9 5or th559and  operati, Q,hat  any9barri962atiod="L282" cla5s="line" 5ame="L322"> 322   9 5 read549mentation/memory-barrier9.txt#963atioTRANSITIVITYd="L282" cla5s="line" 5ame="L322"> 322   9 5OAD o549; Y = *A;
 322   9 5ll th549; Y = *A;
 316   9 4ef="D459mentation/memory-barrier9.txt#96tatioTransitivmtymistory-eplymintuitiv
 316   9 5ef="D549emorBut!,,as c2 depend l9ads i96f="Doalways provmor9"by3realetompuior systems.orTtr followion exampled="L216" cla5s="line" 5ame="L316"> 316   9 5rite 539e otlrede compitnces:
 351   9 5ave a549mentation/memory-barrier9.txt#969atiod="L301" cla5s="line" 5ame="L301"> 301   9h4ef="D479; Y = *A;
 301   9h5!] No509mentation/memory-barrier9.txt#97A-API-HOWTO0"ion/memory-barrory-barriers.txt#L252" iiiiiiiiiiers.txt#L252" iiiiiiiiid="L252" cla5s="line" 5ame="L307"> 307   9h5or th559mentWhilsoblem fa hrbarn9likgs97Ptation/memory-barrie{ X5" 0,tY5" 0o}d="L349" class="line" name="L349"> 349   9h5 read549mentisn depet,Documenif 9whavi97ory-barriers.espectX=riers.txt#L22222LOAD Xers.txt#L222222222espectY=id="L335" cla5s="line" 5ame="L312"> 312   9h5OAD o549mentAlphantation/memory-9arrie97M[Q]tation/memory-barriers.txeeeLLLLL-bargeneral.txt#L335" ieeLLLLL-bargeneral.txt#L335" id="L335" cla5s="line" 5ame="L312"> 312   9h5ll th549mentation/memory-barrier9.txt#97Ptation/memory-barriers.txt#LLLLLLLLLLOAD Yiers.txt#LLLLLLLLLLOAD Xd="L335" cla5s="line" 5ame="L312"> 312   9h4ef="D459s spro da _epeothenify b9rrier97rrierd="L216" cla5s="line" 5ame="L316"> 316   9u5ef="D549ion aetwdento then it'a hro977atioSuppos4 tive=-bari'seriertfrom/XoreturnsrriandLitsbriertfrom/Yoreturnsr0id="L364" class="line" name="L286"> 286
 286
 286
 286
 282VAR9E4IES O489AD *A,  STORB,  4tation/9emory982atioBecause -bari'seriertfrom/Xoi5msent sensr cant ts.txt-barr's#L350e,Litd="L282" cla3s="line" 3ame="L282"> 282VAR9E5 read549AD *B,  X = < href="D9cume
983atios
,natural. icexpntac ive=-bar3'seriertfrom/Xomust eive
ore
 286
 301   9r4 barr489*A = X; Y =             9   Q,98Ptati-barA followsyaeriertfrom/dinmsant variaxt#Lexecue"on og=-barB, dingd="L301" cla5s="line" 5ame="L301"> 301   9h4ef="D489*A = X; Y =             9   &l98rrier-barA'seriertmust eiiertareturn dinmsant valuem ive=-barB'seriertdid,d="L301" cla5s="line" 5ame="L301"> 301   9h5ef="D549*A = Y = X;












9


, 9X*Qtatortmust return sent ltior valueid="L364" class="line" name="L286"> 286
 279int9r4ction479ill r:
 279 286
 286
 286
 286
 294   9 4 writ499atioe me-numbeive.  cer 9err
<99M[Q]tHowever, transitivmtymisr-not-/guaranteedtfoxtiers.oxtriers.txt#L33sid="L364" class="line" name="L286"> 286
 286
 351   9h5ef="D549 meme me-numbeive.bankde9uence9918" id="L318" cla5s="line" 5ame="L338"> 338   9h4>    4t9stemodd-numbeive.bankdse9tdie,99 2, M[3] = 3,-barriers.txt#L222222222-bariiers.txt#L222222222-bar3d="L301" cla5s="line" 5ame="L301"> 301   9h4ction479the  is throold valu seq9ence=999ation/memoryion/memory-barrory-barriers.txt#L252" iiiiiiiiiiers.txt#L252" iiiiiiiiid="L252" cla5s="line" 5ame="L307"> 307   10h5ef="D5c10h5ef is throold valu seq10h5e>10h5tation/memory-barrie{ X5" 0,tY5" 0o}d=/pre> 307   10h1ef="D5c10hentation/memory-barrier10hen>10hrriers.txt#L3espectX=riers.txt#L22222LOAD Xers.txt#L222222222espectY=id="L335" cla5s="line" 5ame="L312"> 312   10h2ef="D5c10h offirst load reall
10hPtation/memory-barriers.txt#Leeeeeeee-bariers.txt#L335" i#Leeeeeeee-bargeneral.txt#L335" id="L335" cla5s="line" 5ame="L312"> 312   10h3ef="D5c10hentmrrierr
10hrrier would be required
gntateeeLLLLLLOAD Yiers.txt#LLLLLLLLLLOAD Xd="L335" cla5s="line" 5ame="L312"> 312   10h4ef="D5c10htioe me-numbeive.  cer 10hti>10h85" id="L285" cla5s="line" 5ame="L325"> 325   10h5ef="D5c10hy elerr
erceivo"oey  su10hy >10h5[Q]tToi msubsistue" 5mdesiroys.transitivmty:atn=ituerexample,ate=s
,-bafntalyd="L285" cla5s="line" 5ame="L325"> 325   10h6ef="D5c10hent="DoassueB mighs bth10hen>10hrrierlega oore -bari'seriertfrom/XotoLreturn 1,Litsbriertfrom/YotoLreturn 0,d="L301" cla5s="line" 5ame="L301"> 301   10h7ef="D5c10hmeme me-numbeive.bankde10hme>10hf="Doand -bar3'seriertfrom/XotoLreturn 0id="L364" class="line" name="L286"> 286
10h89" id="L289" cla4s="line" 4ame="L279"> 279int10h9ef="D5c10hhe  is throold valu seq10hhe>10h9[Q]tToe key= moda 279int1015ef="D5c10AD *B,  X = < href="D10AD >10ADQtatofariers, te=doe
,not/guaranteemtoLoxd79t-barr's#L350e.orTtre
ore
, 279int10A1ef="D5c10AD *B,  STORP,  1ation/m10AD >10A1tatidiuerexample run monya system whee
<-bas riandL2#Lh ksea#L350e bumen0d="L289" cla4s="line" 4ame="L279"> 279int10A2ef="D5c10 = LOAD {*A,,,,,        10 = >10A2Qtatortaerevelers.cache,2-bariimightmha28 early accessL i2-barr's#rierssid="L364" class="line" name="L286"> 286
10ArrierGeneral.txt#L33s- kseeive
ore
 286
10A85" iony iv combeB d oxd79tof2-barr's#and -bari'seaccessssid="L364" class="line" name="L286"> 286
10A16" id="L216" cla5s="line" 5ame="L316"> 316   10A6ef="D5c10mentation/memory-barrier10men>10AtatioToLreersrat
,atfbyour cod
 286
10A7tatidir" /moutid="L364" class="line" name="L286"> 286
10A89" id="L289" cla4s="line" 4ame="L279"> 279int1019ef="D5c10g send load is i RCU dep10g s>10A9atiod="L301" cla5s="line" 5ame="L301"> 301   1025ef="D5c10mentenepreplaciarriond l10men>10meatioers.txt#L252" iiiiiiiiiid="L252" cla5s="line" 5ame="L307"> 307   1021ef="D5c10mentation/memory-barrier10men>10m1tatiEXPLICIT KERNEL BARRIERSd="L252" cla5s="line" 5ame="L307"> 307   1022ef="D5c10mentrol alsoa="Doc infor10men>10m2atioers.txt#L252" iiiiiiiiiid="L252" cla5s="line" 5ame="L307"> 307   1023ef="D5c10mentation/memory-barrier10men>10m94" id="L294" cla3s="line" 3ame="L294"> 294   10m4ef="D5c10mentation/memory-barrier10men>10m4[Q]tToe Linux kernel hasba varietytof2dimen0" i txt#L33s-tive=ace=at2dimen0" id="L294" cla3s="line" 3ame="L294"> 294   10m5ef="D5c10y baCONTROL DEPENDENCIEn10y b>10m5rierlevel id="L286" cla4s="line" 4ame="L351"> 351   10m6ef="D5c10poneument-
 316   10m7ef="D5c10mentation/memory-barrier10men>10m*Qtatio(*) Compil79t6"> 316id="L364" class="line" name="L286"> 286
10m89" id="L289" cla4s="line" 4ame="L279"> 279int1029ef="D5c10g ses should normally  m10g s>10m9Qtatio(*) Cbarme="L3 9"> 279 286
10th9" id="L289" cla4s="line" 4ame="L279"> 279int1031ef="D5c10mentation/memory-barrier10men>10t1Qtatio(*) MMIOtriers.txt#L33id="L364" class="line" name="L286"> 286
10t2atiod="L282" cla5s="line" 5ame="L322"> 322   10t3ef="D5c10*A = X; Y = if (p)ation/10*A >10t94" id="L294" cla3s="line" 3ame="L294"> 294   1034ef="D5c10*A = Y = X;








q,  10*A >10t4[Q]tCOMPILER BARRIERd="L294" cla3s="line" 3ame="L294"> 294   1035ef="D5c10AD *B,  X = <rrier wo10AD >10t55" i----------------d="L282" cla5s="line" 5ame="L322"> 322   10t6ef="D5c10 = LOAD {*A,x  X*qtation10 = >10trrierd="L216" cla5s="line" 5ame="L316"> 316   1037ef="D5c10mentation/memory-barrier10men>10t7[Q]tToe Linux kernel hasba5mexplicittcompil79t6"> 316 funce" 5m mve= rx286tsbeivd="L289" cla4s="line" 4ame="L279"> 279int10t8ef="D5c10ill r:
10t8atiocompil79tfrom/movion #L36me="L3 accessss eiiertaemortof2it" icoma#oiertaemorid="L286" cla4s="line" 4ame="L351"> 351   1039ef="D5c10g ses should ncy is f="D10g s>10t9atiod="L301" cla5s="line" 5ame="L301"> 301   1045ef="D5c10 = Latas
pte compipcumic10 = >10 =rier would b1"> 301()id="L335" cla5s="line" 5ame="L312"> 312   1041ef="D5c10 = Lct"Documesetation/me10 = >10 82" id="L282" cla3s="line" 3ame="L282"> 282VAR10 2ef="D5c10mentation/memory-barrier10men>10 2atioToi misba general.txt#L33<-eresssr varietio moftcompil79t6"> 316 do,not/existid="L364" class="line" name="L286"> 286
10 94" id="L294" cla3s="line" 3ame="L294"> 294   1044ef="D5c10*A = X; Y = if (p)ation/10*A >10 4[Q]tToe compil79t6"> 316 has no diy ce=umentacony iv Cba, oresat#L27ting reoxd79d="L294" cla3s="line" 3ame="L294"> 294   1045ef="D5c10*A = X; Y =         q,  10*A >10 5tatidiungs however2it"wishssid="L364" class="line" name="L286"> 286
10 rrierd="L216" cla5s="line" 5ame="L316"> 316   1047ef="D5c10 = LOAD {*A,x  X*qtation10 = >10 18" id="L318" cla5s="line" 5ame="L338"> 338   10 8ef="D5c10mentation/memory-barrier10men>10 8rier-barMEMORY BARRIERSd="L318" cla5s="line" 5ame="L338"> 338   10 9ef="D5c10mentation/memory-barrier10men>10 95" i-------------------d="L282" cla5s="line" 5ame="L322"> 322   1055ef="D5c10mentg&quBDocume PAIRINGa10men>10me8" id="L318" cla5s="line" 5ame="L338"> 338   1051ef="D5c10mentment-
 279 351   1052ef="D5c10mentation/memory-barrier10men>10m2atiod="L282" cla5s="line" 5ame="L322"> 322   1053ef="D5c10 = LWnrnDda _e cos;
10mrrier would bTYPExt#LLLLLLLLLMANDATORY txt#L222222222eMP CONDITIONALd="L282" cla5s="line" 5ame="L322"> 322   1054ef="D5c10; Y  305 (2) 5at5tru10; Y>10mM[Q]tation/mery-barrory-barriers.txt#L252" iiiiiiiiiiers.txt#L252" iiiiiiiiiiiiid="L252" cla5s="line" 5ame="L307"> 307   1055ef="D5c10AD *A,  STORB,  4tation/10AD >10mPtation/memorGENERAL222222222mb()quired
gntateeeLLLLLsmp_mb()d="L252" cla5s="line" 5ame="L307"> 307   1056ef="D5c10AD *B,  X = < href="D10AD >10mrrier would bWRITExt#LLLLLLLLwmb()quired
gntateeeLLLLsmp_wmb()d="L252" cla5s="line" 5ame="L307"> 307   1057ef="D5c10AD *B,  STORP,  &tat10AD >10m*Qtation/memoREAD            rmb()quired
gntateeeLLLLsmp_rmb()d="L252" cla5s="line" 5ame="L307"> 307   1058ef="D5c10*A = X; Y =             10*A >10m 2, M[3] = 3,DATA DEPENDENCYe.hre_7"> 307_y-barrs()qusmp_rhre_7"> 307_y-barrs()d="L252" cla5s="line" 5ame="L307"> 307   1059ef="D5c10*A = Y = X;












10*A >10m9atiod="L301" cla5s="line" 5ame="L301"> 301   1065ef="D5c10mentation/memory-barrier10men>10meatiod="L301" cla5s="line" 5ame="L301"> 301   1061ef="D5c10s spT per dependenclre a10s s>10m1[Q]tAll.me="L3 9"> 279 301   1062ef="D5c10and  operati, Q,hat  any10and>10m2atiotxt#L33i Demory-barrierio mdo,not/impos4 any3addie" 5aletompil79tentationid="L364" class="line" name="L286"> 286
10m94" id="L294" cla3s="line" 3ame="L294"> 294   1064ef="D5c10; Y = *A;
10mM[Q]tAemori In dinmcase of2demory-barrierio ,y iv compil79twouldobeLexpnta d ced="L294" cla3s="line" 3ame="L294"> 294   1065ef="D5c10; Y = *A;
10m5rierissuebeiveriers 294   1066ef="D5c10mentation/memory-barrier10men>10m6Qtatofab bfore
 294   1067ef="D5c10emorBut!,,as c2 depend l10emo>10m7tatidive=itr compil79t#L27not/specultioL iv valuemofab (eg. uerequal. ic1)#and rierd="L294" cla3s="line" 3ame="L294"> 294   1068ef="D5c10e otlrede compitnces:
10m 2, Ma bfore
 279int1069ef="D5c10mentation/memory-barrier10men>10m9atioproblemmofaa compil79mrerierion b ts.txtha2ion rieredLt[b],y iustha2ion a new79d="L301" cla5s="line" 5ame="L301"> 301   1075ef="D5c10; Y = *A;
10; atiocopymofab divnLt[b]. A c/meensus has not yet bfng reachedmab" iaeivsr problems,d="L301" cla5s="line" 5ame="L301"> 301   1071ef="D5c10mentation/memory-barrier10men>10;1[Q]thowever2eiv ACCESS_ONCEt#Lcromisba good plac8  i2stare riokionid="L364" class="line" name="L286"> 286
10;2atiod="L282" cla5s="line" 5ame="L322"> 322   1073ef="D5c10mentisn depet,Documenif 10men>10;94" ieMP me="L3 9"> 279 316 monyuniprocessoricompil7rd="L294" cla3s="line" 3ame="L294"> 294   1074ef="D5c10mentAlphantation/memory-10men>10;M[Q]tsystemsibecause te=s
,phas="dL ive=a Cbarbee oappear ceins self-c/memst"li,d="L301" cla5s="line" 5ame="L301"> 301   1075ef="D5c10mentation/memory-barrier10men>10;5="Doand bee ooxd79toverlappion accessss cory cely wiie respntac o/itselfid="L364" class="line" name="L286"> 286
10;rrierd="L216" cla5s="line" 5ame="L316"> 316   1077ef="D5c10ion aetwdento then itĶion>10;7tati[!] Note tive=eMP me="L3 9"> 279 279int10;8ef="D5c10mentation/memory-barrier10men>10;8-APIreen0" cesL i2Lh ksd/me="L3 onyeMP systems,540" /metxttuseers.lockioneinsteerd="L294" cla3s="line" 3ame="L294"> 294   1079ef="D5c10 = LOAD {*A,as c1AD {*A,10 = >10;9rierisrsuffici"liid="L364" class="line" name="L286"> 286
 316   1081ef="D5c10; Y = *A;
10 1[Q]tMandat"L3 9"> 279 316   1082ef="D5c10AD *A,  STORB,  4tation/10AD >10 2atiotxt#L33syunnecessarilymimpos4 overhers.on UP systems.oTxty #L2, however, bfd="L216" cla5s="line" 5ame="L316"> 316   1083ef="D5c10AD *B,  X = < href="D10AD >10 94" iused ceicontrolcMMIOtumentasmonyaccessss dir" /mmreraxsd/me="L3 I/O windowsid="L364" class="line" name="L286"> 286
10 4[Q]tToes4 ae
 286
10 5="Dome="L3 opsrati 5s- ppear ceiory-vi34wby prohibie"on both=itr compil79tandL ivd="L364" class="line" name="L286"> 286
10 rrier-barfrom/reoxd79ion #L3mid="L364" class="line" name="L286"> 286
10 18" id="L318" cla5s="line" 5ame="L338"> 338   1088ef="D5c10mentation/memory-barrier10men>10 89" id="L289" cla4s="line" 4ame="L279"> 279int1089ef="D5c10ill r:
10 9[Q]tToer4 ae
 316 funce" 5 351   1095ef="D5c10mentenirdn"Documilito th10men>10me9" id="L289" cla4s="line" 4ame="L279"> 279int1091ef="D5c10mentation/memory-barrier10men>10m1Qtati(*) set_mb(var, value)d="L252" cla5s="line" 5ame="L307"> 307   1092ef="D5c10s offirst load reall
10m2atiod="L282" cla5s="line" 5ame="L322"> 322   1093ef="D5c10mentmrrierr
10mrrier woulToi mrieignsbeiv valuem iLeiv variaxt#LandL ivn insertsba full.me="L3d="L282" cla5s="line" 5ame="L322"> 322   1094ef="D5c10atioe me-numbeive.  cer 10ati>10mM[Q]tationtation/mas.txtit,ry-barr"on og=eiv funce" 5.  Ie=s
6'tmguaranteedtced="L294" cla3s="line" 3ame="L294"> 294   1095ef="D5c10ny elerr
erceivo"oey  su10ny >10mPtation/meinsert anydiung mre
 316 in a UP compilne" 3id="L364" class="line" name="L286"> 286
10mrrierd="L216" cla5s="line" 5ame="L316"> 316   1097ef="D5c10 meme me-numbeive.bankde10 me>10m18" id="L318" cla5s="line" 5ame="L338"> 338   1098ef="D5c10stemodd-numbeive.bankdse10ste>10m8Qtati(*) smp_mb__bfore
_at"mic_dec()id="L335" cla5s="line" 5ame="L312"> 312   1099ef="D5c10the  is throold valu seq10the>10m9Qtati(*) smp_mb__as.tx_at"mic_dec()id="L335" cla5s="line" 5ame="L312"> 312   11h5ef="D5c11h5ef is throold valu seq11h5e>11h5tatio(*) smp_mb__bfore
_at"mic_iL3()id="L335" cla5s="line" 5ame="L312"> 312   11h1ef="D5c11hentation/memory-barrier11hen>1101Qtati(*) smp_mb__as.tx_at"mic_iL3()id="L335" cla5s="line" 5ame="L312"> 312   11h2ef="D5c11h offirst load reall
1102atiod="L282" cla5s="line" 5ame="L322"> 322   11h3ef="D5c11hentmrrierr
110rrier woulToes4 ae
 322   11h4ef="D5c11htioe me-numbeive.  cer 11hti>110M[Q]tationfunce" 5< tive=do6'tmreturn a value, espntiallyowivn used foxtieen0" ced="L282" cla5s="line" 5ame="L322"> 322   11h5ef="D5c11hy elerr
erceivo"oey  su11hy >110Ptation/mecoune"on.ulToes4 funce" 5< do,not/implyome="L3 9"> 279 286
110rrierd="L216" cla5s="line" 5ame="L316"> 316   1107ef="D5c11hmeme me-numbeive.bankde11hme>110*Qtation/mAsra5mexample, c/memory a piecemoftcode tive=marksra5mobjntacasrbeion deerd="L294" cla3s="line" 3ame="L294"> 294   11h8ef="D5c11htemodd-numbeive.bankdse11hte>110 2, M[3] =andL ivn decre="lisbeiv objnta'se.hen0" ceecouneid="L286" cla4s="line" 4ame="L351"> 351   11h9ef="D5c11hhe  is throold valu seq11hhe>1109atiod="L301" cla5s="line" 5ame="L301"> 301   1115ef="D5c11AD *B,  X = < href="D11AD >11ntation/memoryobj 5" ideer = 1id="L335" cla5s="line" 5ame="L312"> 312   11A1ef="D5c11AD *B,  STORP,  1ation/m11AD >111A-API-HOWTO0"smp_mb__bfore
_at"mic_dec()id="L335" cla5s="line" 5ame="L312"> 312   11A2ef="D5c11 = LOAD {*A,,,,,        11 = >11 Ptation/memorat"mic_dec(&obj 5" i35"_coune)id="L335" cla5s="line" 5ame="L312"> 312   11A3ef="D5c11*A = X; Y =             11*A >11194" id="L294" cla3s="line" 3ame="L294"> 294   11A4ef="D5c11*A = Y = X;












11*A >11XM[Q]tationToi mmakesrsure tive= iv death=mark og=eiv objntacs
,-baceiv d ceins setd="L294" cla3s="line" 3ame="L294"> 294   11A5ef="D5c11mentation/memory-barrier11men>111Ptation/me*bfore
*=eiv .hen0" ceecoune16 is decre="liedid="L364" class="line" name="L286"> 286
111rrierd="L216" cla5s="line" 5ame="L316"> 316   11A7ef="D5c11mentThrfrriers should no11men>111*Qtation/mSee la5s="line" 5aat"mic_op  foxtmre
 316   11A8ef="D5c11ned rol rcu_ceivff tnce(11ned>111 2, M[3] =opsrati 5s"msubsece" 5mfoxtinfoxmae" 5 og=whee
 286
11A9atiod="L301" cla5s="line" 5ame="L301"> 301   1125ef="D5c11mentenepreplaciarriond l11men>112e9" id="L289" cla4s="line" 4ame="L279"> 279int1121ef="D5c11mentation/memory-barrier11men>1121Qtati(*) smp_mb__bfore
_clear_bit(void)id="L335" cla5s="line" 5ame="L312"> 312   1122ef="D5c11mentrol alsoa="Doc infor11men>112Ptatio(*) smp_mb__as.tx_clear_bit(void)id="L335" cla5s="line" 5ame="L312"> 312   1123ef="D5c11mentation/memory-barrier11men>11m94" id="L294" cla3s="line" 3ame="L294"> 294   11m4ef="D5c11mentation/memory-barrier11men>1124rier woulToes4 ae
 279 294   11m5ef="D5c11y baCONTROL DEPENDENCIEn11y b>112Ptation/metypicallyoused foxtbitwis4 unlockioneopsrati 5s,asoLc#e
 286
 279 286
11218" id="L318" cla5s="line" 5ame="L338"> 338   1128ef="D5c11ned Ay.  If the address 11ned>112Ptation/meC/memory imple="liion an unlockeopsrati 5moftsent natur4wby clearion ad="L318" cla5s="line" 5ame="L338"> 338   1129ef="D5c11g ses should normally  m11g s>112*Qtation/mlockionebit.orTtr clear_bit()twouldo ivn ne d ceins 8"> 338 d like=itueid="L286" cla4s="line" 4ame="L351"> 351   1135ef="D5c11thataodetation/memory-ba11tha>11th9" id="L289" cla4s="line" 4ame="L279"> 279int1131ef="D5c11mentation/memory-barrier11men>113A-API-HOWTO0"smp_mb__bfore
_clear_bit()id="L335" cla5s="line" 5ame="L312"> 312   1132ef="D5c11 = LOAD {*A,q,  &ata11 = >113Ptation/memorclear_bit( ... )id="L335" cla5s="line" 5ame="L312"> 312   1133ef="D5c11*A = X; Y = if (p)ation/11*A >11t94" id="L294" cla3s="line" 3ame="L294"> 294   1134ef="D5c11*A = Y = X;








q,  11*A >113M[Q]tationToi m rx286tsbme="L3 opsrati 5s-bfore
 294   1135ef="D5c11AD *B,  X = <rrier wo11AD >113Ptation/medinmsubsece" 5mog "LockioneFunce" 5<"mwiie reen0" ceeceiUNLOCK opsrati 5d="L294" cla3s="line" 3ame="L294"> 294   1136ef="D5c11 = LOAD {*A,x  X*qtation11 = >113rrier woulimplicati 5sid="L364" class="line" name="L286"> 286
11318" id="L318" cla5s="line" 5ame="L338"> 338   11t8ef="D5c11ill r:
113Ptation/meSee la5s="line" 5aat"mic_op  foxtmre
 316   1139ef="D5c11g ses should ncy is f="D11g s>11392, M[3] =opsrati 5s"msubsece" 5mfoxtinfoxmae" 5 og=whee
 286
1140atiod="L301" cla5s="line" 5ame="L301"> 301   1141ef="D5c11 = Lct"Documesetation/me11 = >11 82" id="L282" cla3s="line" 3ame="L282"> 282VAR11 2ef="D5c11mentation/memory-barrier11men>11 2atioMMIOtWRITExBARRIERd="L294" cla3s="line" 3ame="L294"> 294   1143ef="D5c11 = LOAD {*A,q,  &ata11 = >11 94" i------------------d="L282" cla5s="line" 5ame="L322"> 322   1144ef="D5c11*A = X; Y = if (p)ation/11*A >11485" id="L285" cla5s="line" 5ame="L325"> 325   1145ef="D5c11*A = X; Y =         q,  11*A >1145[Q]tToe Linux kernel alsoLhasba spntialt6"> 316 fre useewiie me="L32m pped I/Od="L285" cla5s="line" 5ame="L325"> 325   1146ef="D5c11AD *B,  X = <ld norma11AD >11 rrierrierssid="L286" cla4s="line" 4ame="L351"> 351   1147ef="D5c11 = LOAD {*A,x  X*qtation11 = >11 18" id="L318" cla5s="line" 5ame="L338"> 338   11 8ef="D5c11mentation/memory-barrier11men>114Ptation/memormmiowb()id="L335" cla5s="line" 5ame="L312"> 312   11 9ef="D5c11mentation/memory-barrier11men>1149atiod="L301" cla5s="line" 5ame="L301"> 301   1155ef="D5c11mentg&quBDocume PAIRINGa11men>11me8" iToi misba variae" 5 og=#L36mandat"L3 riers.txt#L33 tive=causes#rierss 325   1151ef="D5c11mentment-
 286
11m2atioCPU 5" iHardwae
 286
11594" id="L294" cla3s="line" 3ame="L294"> 294   1154ef="D5c11; Y  305 (2) 5at5tru11; Y>11mM[Q]tSee eiv subsece" 5m"Locks vs I/O accessss"mfoxtmre
 294   1155ef="D5c11AD *A,  STORB,  4tation/11AD >11516" id="L216" cla5s="line" 5ame="L316"> 316   1156ef="D5c11AD *B,  X = < href="D11AD >115rrierd="L216" cla5s="line" 5ame="L316"> 316   1157ef="D5c11AD *B,  STORP,  &tat11AD >11m*Qtaters.txt#L252" iiiiiiiiiiiiiiiiid="L252" cla5s="line" 5ame="L307"> 307   1158ef="D5c11*A = X; Y =             11*A >11m 2, MIMPLICIT KERNEL MEMORY BARRIERSd="L318" cla5s="line" 5ame="L338"> 338   1159ef="D5c11*A = Y = X;












11*A >11m9atioers.txt#L252" iiiiiiiiiiiiiiiiid="L252" cla5s="line" 5ame="L307"> 307   1165ef="D5c11mentation/memory-barrier11men>11meatiod="L301" cla5s="line" 5ame="L301"> 301   1161ef="D5c11s spT per dependenclre a11s s>11m1[Q]tSent ofcoma#oiertafunce" 5< sny iv linux kernel implyome="L3 9"> 279<, amongstd="L364" class="line" name="L286"> 286
11m2atiooresatae
 294   1163ef="D5c11mentation/memory-barrier11men>11m94" id="L294" cla3s="line" 3ame="L294"> 294   1164ef="D5c11; Y = *A;
116M[Q]tToi mspecificne" 5misba _minimum_mguarantee; any3particultrtaechersctur4w#L2d="L294" cla3s="line" 3ame="L294"> 294   1165ef="D5c11; Y = *A;
11m5rierprovmortmre
 294   1166ef="D5c11mentation/memory-barrier11men>11m6Qtatofaaechmspecifictcode.d="L294" cla3s="line" 3ame="L294"> 294   1167ef="D5c11emorBut!,,as c2 depend l11emo>11618" id="L318" cla5s="line" 5ame="L338"> 338   1168ef="D5c11e otlrede compitnces:
11689" id="L289" cla4s="line" 4ame="L279"> 279int1169ef="D5c11mentation/memory-barrier11men>11m9atioLOCKING FUNCTIONSd="L318" cla5s="line" 5ame="L338"> 338   1175ef="D5c11; Y = *A;
11; atio-----------------d="L282" cla5s="line" 5ame="L322"> 322   1171ef="D5c11mentation/memory-barrier11men>11782" id="L282" cla3s="line" 3ame="L282"> 282VAR1172ef="D5c11mentWhilsoblem fa hrbarn11men>1172[Q]tToe Linux kernel hasba numb79tof2rickionec"nstrutasid="L286" cla4s="line" 4ame="L351"> 351   1173ef="D5c11mentisn depet,Documenif 11men>11794" id="L294" cla3s="line" 3ame="L294"> 294   1174ef="D5c11mentAlphantation/memory-11men>117M[Q]ta(*) spsnyricksd="L364" class="line" name="L286"> 286
117Ptatio(*) R/W spsnyricksd="L364" class="line" name="L286"> 286
11;rriero(*) mutexesd="L364" class="line" name="L286"> 286
11;7tatii(*) sem phre
sd="L364" class="line" name="L286"> 286
1178tatio(*) R/W sem phre
sd="L364" class="line" name="L286"> 286
1179Qtati(*) RCUd="L364" class="line" name="L286"> 286
 316   1181ef="D5c11; Y = *A;
11 1[Q]tIn=all 316   1182ef="D5c11AD *A,  STORB,  4tation/11AD >11 2atiofoxteachec"nstrutaiulToes4 opsrati 5s- ll implyocertasny6"> 316 351   1183ef="D5c11AD *B,  X = < href="D11AD >11894" id="L294" cla3s="line" 3ame="L294"> 294   1184ef="D5c11AD *B,  STORP,  &tat11AD >118M[Q]ta(1) LOCK opsrati 5limplicati 5id="L286" cla4s="line" 4ame="L351"> 351   1185ef="D5c11*A = X; Y =             11*A >11816" id="L216" cla5s="line" 5ame="L316"> 316   1186ef="D5c11*A = X; Y =             11*A >118rrier woulMe="L3 opsrati 5s-issuedios.txtdinmLOCK bee obr completedios.txtdinmLOCKd="L216" cla5s="line" 5ame="L316"> 316   1187ef="D5c11*A = Y = X;












11*A >118*Qtation/mopsrati 5lhasbcompleted.d="L294" cla3s="line" 3ame="L294"> 294   1188ef="D5c11mentation/memory-barrier11men>11 89" id="L289" cla4s="line" 4ame="L279"> 279int1189ef="D5c11ill r:
1189rier woulMe="L3 opsrati 5s-issuedibfore
 316   1195ef="D5c11mentenirdn"Documilito th11men>1190Qtation/mopsrati 5lhasbcompleted.d="L294" cla3s="line" 3ame="L294"> 294   1191ef="D5c11mentation/memory-barrier11men>11982" id="L282" cla3s="line" 3ame="L282"> 282VAR1192ef="D5c11s offirst load reall
119Ptatio(2)iUNLOCK opsrati 5limplicati 5id="L286" cla4s="line" 4ame="L351"> 351   1193ef="D5c11mentmrrierr
11294" id="L294" cla3s="line" 3ame="L294"> 294   1124ef="D5c11atioe me-numbeive.  cer 11ati>11mM[Q]tationMe="L3 opsrati 5s-issuedibfore
 294   1125ef="D5c11ny elerr
erceivo"oey  su11ny >11mPtation/meUNLOCK opsrati 5lhasbcompleted.d="L294" cla3s="line" 3ame="L294"> 294   1196ef="D5c11ment="DoassueB mighs bth11men>11mrrierd="L216" cla5s="line" 5ame="L316"> 316   1197ef="D5c11 meme me-numbeive.bankde11 me>1197rier woulMe="L3 opsrati 5s-issuedios.txtdinmUNLOCK #L27br completedibfore
 294   1128ef="D5c11stemodd-numbeive.bankdse11ste>119 2, M[3] =UNLOCK opsrati 5lhasbcompleted.d="L294" cla3s="line" 3ame="L294"> 294   1199ef="D5c11the  is throold valu seq11the>1199atiod="L301" cla5s="line" 5ame="L301"> 301   12h5ef="D5c12h5ef is throold valu seq12h5e>12h5tatio(3) LOCK vs LOCK implicati 5id="L286" cla4s="line" 4ame="L351"> 351   12h1ef="D5c12hentation/memory-barrier12hen>12082" id="L282" cla3s="line" 3ame="L282"> 282VAR12h2ef="D5c12h offirst load reall
12hPtation/meAll.LOCK opsrati 5s-issuedibfore
 282VAR12h3ef="D5c12hentmrrierr
120rrier woulbfore
 294   12h4ef="D5c12htioe me-numbeive.  cer 12hti>12h85" id="L285" cla5s="line" 5ame="L325"> 325   12h5ef="D5c12hy elerr
erceivo"oey  su12hy >120Ptatio(4) LOCK vs UNLOCK implicati 5id="L286" cla4s="line" 4ame="L351"> 351   12h6ef="D5c12hent="DoassueB mighs bth12hen>120rrierd="L216" cla5s="line" 5ame="L316"> 316   1207ef="D5c12hmeme me-numbeive.bankde12hme>120*Qtation/mAll.LOCK opsrati 5s-issuedibfore
 282VAR12h8ef="D5c12htemodd-numbeive.bankdse12hte>120 2, M[3] =bfore
 294   12h9ef="D5c12hhe  is throold valu seq12hhe>1209atiod="L301" cla5s="line" 5ame="L301"> 301   1215ef="D5c12AD *B,  X = < href="D12AD >12ntation/memAll.UNLOCK opsrati 5s-issuedibfore
 282VAR12A1ef="D5c12AD *B,  STORP,  1ation/m12AD >121A-API-HOWTbfore
 294   12A2ef="D5c12 = LOAD {*A,,,,,        12 = >1212atiod="L282" cla5s="line" 5ame="L322"> 322   12A3ef="D5c12*A = X; Y =             12*A >12194" i (5) Fail7rec"ndie" 5aleLOCK implicati 5id="L286" cla4s="line" 4ame="L351"> 351   12A4ef="D5c12*A = Y = X;












12*A >12185" id="L285" cla5s="line" 5ame="L325"> 325   12A5ef="D5c12mentation/memory-barrier12men>121Ptation/meCertasnyvarianasmof 325   12A6ef="D5c12mentation/memory-barrier12men>121rrier woulunaxt#L iLgetbeiverick immediately,.oxtduem iLreceivion an unbrickedd="L282" cla3s="line" 3ame="L282"> 282VAR12A7ef="D5c12mentThrfrriers should no12men>121*Qtation/meignalewhilsacasleep waie"on foxteiverick  iLbecent availaxt#.  Fail7rd="L282" cla3s="line" 3ame="L282"> 282VAR12A8ef="D5c12ned rol rcu_ceivff tnce(12ned>121 2, M[3] =ricks do,not/implyoany3sortmofab"> 282.d="L294" cla3s="line" 3ame="L294"> 294   12A9ef="D5c12g send load is i RCU dep12g s>12A9atiod="L301" cla5s="line" 5ame="L301"> 301   1225ef="D5c12mentenepreplaciarriond l12men>122e8" iTore
ore
, 316   1221ef="D5c12mentation/memory-barrier12men>1221Qtatequival"li ceiorfull.6"> 316, b iaaaLOCK followediby an UNLOCK is not.d="L294" cla3s="line" 3ame="L294"> 294   1222ef="D5c12mentrol alsoa="Doc infor12men>1222atiod="L282" cla5s="line" 5ame="L322"> 322   1223ef="D5c12mentation/memory-barrier12men>12m94" i[!] Note: ont ofcoma#c/meequ" cesLofcLOCKs- nd UNLOCKsrbeion onlyoone-wL2d="L294" cla3s="line" 3ame="L294"> 294   12m4ef="D5c12mentation/memory-barrier12men>1224rier wou9"> 279 294   12m5ef="D5c12y baCONTROL DEPENDENCIEn12y b>122Ptation/m#L27seep in iLeiv inemormofaoma#crie"calesece" 5.d="L294" cla3s="line" 3ame="L294"> 294   1226ef="D5c12poneument-
 316   12m7ef="D5c12mentation/memory-barrier12men>12218" iAaLOCK followediby an UNLOCK #L27not/bemahas="dL eins full.me="L3u9"> 279d="L216" cla5s="line" 5ame="L316"> 316   12m8ef="D5c12ned Ay.  If the address 12ned>122Ptatibecause te=s
,possixt#Lfoxtanyaccessm rxcedion #L36LOCK toLhappen as.txtdind="L216" cla5s="line" 5ame="L316"> 316   12m9ef="D5c12g ses should normally  m12g s>1229atioLOCK, andLanyaccessmfollowion #L36UNLOCK toLhappen bfore
 286
12th9" itwo accessss cany ivmselvesltoen#crossid="L286" cla4s="line" 4ame="L351"> 351   1231ef="D5c12mentation/memory-barrier12men>12382" id="L282" cla3s="line" 3ame="L282"> 282VAR1232ef="D5c12 = LOAD {*A,q,  &ata12 = >123Ptation/memor*A =Ltid="L335" cla5s="line" 5ame="L312"> 312   1233ef="D5c12*A = X; Y = if (p)ation/12*A >123rrier would bLOCKd="L216" cla5s="line" 5ame="L316"> 316   1234ef="D5c12*A = Y = X;








q,  12*A >123M[Q]tation/meUNLOCKd="L216" cla5s="line" 5ame="L316"> 316   1235ef="D5c12AD *B,  X = <rrier wo12AD >123Ptation/memor*B =Lbid="L335" cla5s="line" 5ame="L312"> 312   1236ef="D5c12 = LOAD {*A,x  X*qtation12 = >12trrierd="L216" cla5s="line" 5ame="L316"> 316   1237ef="D5c12mentation/memory-barrier12men>12318" i#L27occu/masid="L286" cla4s="line" 4ame="L351"> 351   1238ef="D5c12ill r:
12389" id="L289" cla4s="line" 4ame="L279"> 279int1239ef="D5c12g ses should ncy is f="D12g s>1239rier would bLOCK,2espect*B,2espect*A,eUNLOCKd="L216" cla5s="line" 5ame="L316"> 316   1245ef="D5c12 = Latas
pte compipcumic12 = >1240atiod="L301" cla5s="line" 5ame="L301"> 301   1241ef="D5c12 = Lct"Documesetation/me12 = >12 82" iLocks andLsem phre
s #L27not/provmortany3guaranteemofaontation xn UP compil7rd="L282" cla3s="line" 3ame="L282"> 282VAR12 2ef="D5c12mentation/memory-barrier12men>12 2atiosystems,5andLsoLc#nnot/bemcoune1s.on snysusatameituati 5 ceioctuallyoachievvd="L364" class="line" name="L286"> 286
12 94" ianydiung ve=all<- espntiallyowiie respntac o/I/O accessss<- unress combeB dd="L364" class="line" name="L286"> 286
12485" iwiie in.txrupt2disaxtioneopsrati 5s.d="L294" cla3s="line" 3ame="L294"> 294   1245ef="D5c12*A = X; Y =         q,  12*A >12416" id="L216" cla5s="line" 5ame="L316"> 316   1246ef="D5c12AD *B,  X = <ld norma12AD >12 rrierSee alsoLeiv sece" 5mog "In.tx--barlockionebxt#L33 umentas".d="L294" cla3s="line" 3ame="L294"> 294   1247ef="D5c12 = LOAD {*A,x  X*qtation12 = >12 18" id="L318" cla5s="line" 5ame="L338"> 338   12 8ef="D5c12mentation/memory-barrier12men>12489" id="L289" cla4s="line" 4ame="L279"> 279int12 9ef="D5c12mentation/memory-barrier12men>1249atioAsra5mexample, c/memory eiv followionid="L286" cla4s="line" 4ame="L351"> 351   1255ef="D5c12mentg&quBDocume PAIRINGa12men>12me8" id="L318" cla5s="line" 5ame="L338"> 338   1251ef="D5c12mentment-
 312   1252ef="D5c12mentation/memory-barrier12men>1252tation/memor*B =Lbid="L335" cla5s="line" 5ame="L312"> 312   1253ef="D5c12 = LWnrnDda _e cos;
125rrier would bLOCKd="L216" cla5s="line" 5ame="L316"> 316   1254ef="D5c12; Y  305 (2) 5at5tru12; Y>12mM[Q]tation/me*C =Lcid="L335" cla5s="line" 5ame="L312"> 312   1255ef="D5c12AD *A,  STORB,  4tation/12AD >12mPtation/memor*D =Ldid="L335" cla5s="line" 5ame="L312"> 312   1256ef="D5c12AD *B,  X = < href="D12AD >12mrrier would bUNLOCKd="L216" cla5s="line" 5ame="L316"> 316   1257ef="D5c12AD *B,  STORP,  &tat12AD >12m*Qtation/memo*E =Leid="L335" cla5s="line" 5ame="L312"> 312   1258ef="D5c12*A = X; Y =             12*A >12m 2, M[3] = 3,*F =Lfid="L335" cla5s="line" 5ame="L312"> 312   1259ef="D5c12*A = Y = X;












12*A >12m9atiod="L301" cla5s="line" 5ame="L301"> 301   1265ef="D5c12mentation/memory-barrier12men>126e8" iTormfollowion eequ" cemofax286tsbiseacceptaxt#id="L286" cla4s="line" 4ame="L351"> 351   1261ef="D5c12s spT per dependenclre a12s s>12682" id="L282" cla3s="line" 3ame="L282"> 282VAR12m2ef="D5c12and  operati, Q,hat  any12and>1262rier would bLOCK,2{*F,*A},o*E,2{*C,*D},o*B,eUNLOCKd="L216" cla5s="line" 5ame="L316"> 316   1263ef="D5c12mentation/memory-barrier12men>12m94" id="L294" cla3s="line" 3ame="L294"> 294   1264ef="D5c12; Y = *A;
126M[Q]tation/me[+] Note tive={*F,*A} indicatesLt combeB d access.d="L294" cla3s="line" 3ame="L294"> 294   1265ef="D5c12; Y = *A;
12616" id="L216" cla5s="line" 5ame="L316"> 316   1266ef="D5c12mentation/memory-barrier12men>12m6QtatButynonrmofaoma#followion ar#id="L286" cla4s="line" 4ame="L351"> 351   1267ef="D5c12emorBut!,,as c2 depend l12emo>12618" id="L318" cla5s="line" 5ame="L338"> 338   1268ef="D5c12e otlrede compitnces:
126 2, M[3] = 3,{*F,*A},o*B,ed bLOCK,2*C,r*D,d bUNLOCK,o*Ed="L318" cla5s="line" 5ame="L338"> 338   1269ef="D5c12mentation/memory-barrier12men>1269tation/memor*A,o*B,e*C,red bLOCK,2*D,would bUNLOCK,o*E,2*Fd="L318" cla5s="line" 5ame="L338"> 338   1275ef="D5c12; Y = *A;
1270tation/memor*A,o*B,e would bLOCK,2*C,red b bUNLOCK,o*D,o*E,2*Fd="L318" cla5s="line" 5ame="L338"> 338   1271ef="D5c12mentation/memory-barrier12men>1271tation/memor*B,e would bed bLOCK,2*C,r*D,d bUNLOCK,o{*F,*A},o*Ed="L318" cla5s="line" 5ame="L338"> 338   1272ef="D5c12mentWhilsoblem fa hrbarn12men>12;2atiod="L282" cla5s="line" 5ame="L322"> 322   1273ef="D5c12mentisn depet,Documenif 12men>12794" id="L294" cla3s="line" 3ame="L294"> 294   1274ef="D5c12mentAlphantation/memory-12men>12785" id="L285" cla5s="line" 5ame="L325"> 325   1275ef="D5c12mentation/memory-barrier12men>127PtatiINTERRUPT DISABLING FUNCTIONSd="L318" cla5s="line" 5ame="L338"> 338   1276ef="D5c12s spro da _epeothenify b12s s>12;rrier-----------------------------d="L282" cla5s="line" 5ame="L322"> 322   12;7ef="D5c12ion aetwdento then itĸion>12718" id="L318" cla5s="line" 5ame="L338"> 338   12;8ef="D5c12mentation/memory-barrier12men>1278tatiFunce" 5< tive=disaxte in.txrupts (LOCK equival"li)i nd enaxte in.txruptsd="L318" cla5s="line" 5ame="L338"> 338   12;9ef="D5c12 = LOAD {*A,as c1AD {*A,12 = >1279Qtat(UNLOCK equival"li)ibee oatacasrcompil79t6"> 316 monly.  Soatfbme="L3uor I/Od="L285" cla5s="line" 5ame="L325"> 325   1285ef="D5c12 = LOAD {*A, href="Docum12 = >12 =rier6"> 316 mae
 325   1281ef="D5c12; Y = *A;
12 1[Q]toiertamea5s.d="L294" cla3s="line" 3ame="L294"> 294   1282ef="D5c12AD *A,  STORB,  4tation/12AD >1282atiod="L282" cla5s="line" 5ame="L322"> 322   1283ef="D5c12AD *B,  X = < href="D12AD >12894" id="L294" cla3s="line" 3ame="L294"> 294   1284ef="D5c12AD *B,  STORP,  &tat12AD >128M[Q]tSLEEP AND WAKE-UP FUNCTIONSd="L318" cla5s="line" 5ame="L338"> 338   1285ef="D5c12*A = X; Y =             12*A >12816" i---------------------------d="L282" cla5s="line" 5ame="L322"> 322   1286ef="D5c12*A = X; Y =             12*A >128rrierd="L216" cla5s="line" 5ame="L316"> 316   1287ef="D5c12*A = Y = X;












12*A >128*QtatSleepioneandLwakioneonyanax286t flagg d snyglobal2demorcanybftviewediasba5d="L294" cla3s="line" 3ame="L294"> 294   1288ef="D5c12mentation/memory-barrier12men>12 89" iin.txace" 5mbetwfng two pieces of2demo:aoma#task2statrmofaoma#task2waie"on foxd="L294" cla3s="line" 3ame="L294"> 294   1289ef="D5c12ill r:
1289rieroma#u286t andL ivyglobal2demorused ceiindicate oma#u286tiulTommakersure tived="L294" cla3s="line" 3ame="L294"> 294   1295ef="D5c12mentenirdn"Documilito th12men>1290Qtateivsr  ppear ceihappen sny iv rightmontat,y iv primie"ve< teinsgsny iv processd="L294" cla3s="line" 3ame="L294"> 294   1291ef="D5c12mentation/memory-barrier12men>12982" iofagoioneceisleep,tandL iv primie"ve< teiinie"ate aLwake up implyocertasnd="L294" cla3s="line" 3ame="L294"> 294   1292ef="D5c12s offirst load reall
1292atiotxt#L33s.d="L294" cla3s="line" 3ame="L294"> 294   1293ef="D5c12mentmrrierr
12294" id="L294" cla3s="line" 3ame="L294"> 294   1224ef="D5c12atioe me-numbeive.  cer 12ati>12mM[Q]tFirstly,.eiv sleeprtanoxmallyofollows/sentdiung like=itue eequ" cemofax286tsid="L286" cla4s="line" 4ame="L351"> 351   1225ef="D5c12ny elerr
erceivo"oey  su12ny >12916" id="L216" cla5s="line" 5ame="L316"> 316   1296ef="D5c12ment="DoassueB mighs bth12men>129rrier would bfoxt(;;) {d="L216" cla5s="line" 5ame="L316"> 316   1297ef="D5c12 meme me-numbeive.bankde12 me>129*Qtation/memoooooooooset_curr"li_statr(TASK_UNINTERRUPTIBLE)id="L335" cla5s="line" 5ame="L312"> 312   1228ef="D5c12stemodd-numbeive.bankdse12ste>1298Qtation/memoooooooootfb(x286t_indicated)d="L252" cla5s="line" 5ame="L307"> 307   1299ef="D5c12the  is throold valu seq12the>1299Qtation/memooooooooooooooooobreakid="L335" cla5s="line" 5ame="L312"> 312   13h5ef="D5c13h5ef is throold valu seq13h5e>1300Qtation/memoooooooooschedule()id="L335" cla5s="line" 5ame="L312"> 312   13h1ef="D5c13hentation/memory-barrier13hen>1301tation/memor}d="L335" cla5s="line" 5ame="L312"> 312   13h2ef="D5c13h offirst load reall
1302atiod="L282" cla5s="line" 5ame="L322"> 322   13h3ef="D5c13hentmrrierr
130rrierA gentxal.me="L3u9"> 279bisein.txpoltiodiautomae"callyobyoset_curr"li_statr()d="L252" cla5s="line" 5ame="L307"> 307   13h4ef="D5c13htioe me-numbeive.  cer 13hti>13h85" ios.txtit hasbalt79ed oma#task2statrid="L286" cla4s="line" 4ame="L351"> 351   13h5ef="D5c13hy elerr
erceivo"oey  su13hy >13016" id="L216" cla5s="line" 5ame="L316"> 316   13h6ef="D5c13hent="DoassueB mighs bth13hen>130rrier would b-bar1d="L216" cla5s="line" 5ame="L316"> 316   13h7ef="D5c13hmeme me-numbeive.bankde13hme>130*Qtation/memoers.txt#L252" iiiiiiiiiiiiiiiiid="L252" cla5s="line" 5ame="L307"> 307   13h8ef="D5c13htemodd-numbeive.bankdse13hte>1308Qtation/memoset_curr"li_statr()id="L335" cla5s="line" 5ame="L312"> 312   13h9ef="D5c13hhe  is throold valu seq13hhe>1309Qtation/memoooset_mb()id="L335" cla5s="line" 5ame="L312"> 312   1315ef="D5c13AD *B,  X = < href="D13AD >1310Qtation/memoooooespectcurr"li 5" istatrd="L335" cla5s="line" 5ame="L312"> 312   1311ef="D5c13AD *B,  STORP,  1ation/m13AD >131A-API-HOWTO0"""""<gentxal.2"> 3125" id="L335" cla5s="line" 5ame="L312"> 312   1312ef="D5c13 = LOAD {*A,,,,,        13 = >1312rier would bLOAD x286t_indicatedd="L335" cla5s="line" 5ame="L312"> 312   1313ef="D5c13*A = X; Y =             13*A >13194" id="L294" cla3s="line" 3ame="L294"> 294   13A4ef="D5c13*A = Y = X;












13*A >13185" iset_curr"li_statr() #L27br wr pped byid="L286" cla4s="line" 4ame="L351"> 351   13A5ef="D5c13mentation/memory-barrier13men>13116" id="L216" cla5s="line" 5ame="L316"> 316   13A6ef="D5c13mentation/memory-barrier13men>131rrier would bprepare_to_waie()id="L335" cla5s="line" 5ame="L312"> 312   1317ef="D5c13mentThrfrriers should no13men>1317rier would bprepare_to_waie_exclus"ve()id="L335" cla5s="line" 5ame="L312"> 312   1318ef="D5c13ned rol rcu_ceivff tnce(13ned>13189" id="L289" cla4s="line" 4ame="L279"> 279int13A9ef="D5c13g send load is i RCU dep13g s>13A9atiooresattore
ore
 alsoLimplyoa gentxal.me="L3u9"> 279bos.txtsettion #L36statr.d="L294" cla3s="line" 3ame="L294"> 294   1325ef="D5c13mentenepreplaciarriond l13men>132e8" iTor whole eequ" cemabovebiseavailaxt# snyvarious canned foxms,5ae oof oresad="L364" class="line" name="L286"> 286
1321Qtatin.txpoltio=#L36me="L3u9"> 279biny iv rightmplac8id="L286" cla4s="line" 4ame="L351"> 351   1322ef="D5c13mentrol alsoa="Doc infor13men>1322atiod="L282" cla5s="line" 5ame="L322"> 322   1323ef="D5c13mentation/memory-barrier13men>132rrier would bwaie_e286t()id="L335" cla5s="line" 5ame="L312"> 312   13m4ef="D5c13mentation/memory-barrier13men>1324rier would bwaie_e286t_in.txruptixt#()id="L335" cla5s="line" 5ame="L312"> 312   13m5ef="D5c13y baCONTROL DEPENDENCIEn13y b>1325rier would bwaie_e286t_in.txruptixt#_exclus"ve()id="L335" cla5s="line" 5ame="L312"> 312   1326ef="D5c13poneument-
 312   13m7ef="D5c13mentation/memory-barrier13men>1327rier would bwaie_e286t_killaxt#()id="L335" cla5s="line" 5ame="L312"> 312   13m8ef="D5c13ned Ay.  If the address 13ned>1328rier would bwaie_e286t_timeout()id="L335" cla5s="line" 5ame="L312"> 312   13m9ef="D5c13g ses should normally  m13g s>1329rier would bwaie_on_bit()id="L335" cla5s="line" 5ame="L312"> 312   1335ef="D5c13thataodetation/memory-ba13tha>1330rier would bwaie_on_bit_lock()id="L335" cla5s="line" 5ame="L312"> 312   1331ef="D5c13mentation/memory-barrier13men>13382" id="L282" cla3s="line" 3ame="L282"> 282VAR1332ef="D5c13 = LOAD {*A,q,  &ata13 = >1332atiod="L282" cla5s="line" 5ame="L322"> 322   1333ef="D5c13*A = X; Y = if (p)ation/13*A >133rrierSec"ndly,.code tive=perfoxms aLwake up noxmallyofollows/sentdiung like=itueid="L286" cla4s="line" 4ame="L351"> 351   1334ef="D5c13*A = Y = X;








q,  13*A >13385" id="L285" cla5s="line" 5ame="L325"> 325   1335ef="D5c13AD *B,  X = <rrier wo13AD >133Ptation/memorx286t_indicated = 1id="L335" cla5s="line" 5ame="L312"> 312   1336ef="D5c13 = LOAD {*A,x  X*qtation13 = >1336rier would bwake_up(&x286t_waie_qu"ue)id="L335" cla5s="line" 5ame="L312"> 312   1337ef="D5c13mentation/memory-barrier13men>13318" id="L318" cla5s="line" 5ame="L338"> 338   1338ef="D5c13ill r:
13389" iorid="L286" cla4s="line" 4ame="L351"> 351   1339ef="D5c13g ses should ncy is f="D13g s>1339atiod="L301" cla5s="line" 5ame="L301"> 301   1345ef="D5c13 = Latas
pte compipcumic13 = >1340tation/memorx286t_indicated = 1id="L335" cla5s="line" 5ame="L312"> 312   1341ef="D5c13 = Lct"Documesetation/me13 = >1341rier would bwake_up_process(x286t_dae="n)id="L335" cla5s="line" 5ame="L312"> 312   13 2ef="D5c13mentation/memory-barrier13men>1342atiod="L282" cla5s="line" 5ame="L322"> 322   1343ef="D5c13 = LOAD {*A,q,  &ata13 = >134rrierA riers.me="L3u9"> 279biseimpliediby wake_up()i nd co.otfb nd onlyoifbeity waked="L282" cla5s="line" 5ame="L322"> 322   1344ef="D5c13*A = X; Y = if (p)ation/13*A >13485" isentdiung up.orTtr 9"> 279boccu/s-bfore
 338   1345ef="D5c13*A = X; Y =         q,  13*A >13416" ibetwfng t hrespectceiindicate oma#u286ttandL iv espectceiset TASK_RUNNINGid="L286" cla4s="line" 4ame="L351"> 351   1346ef="D5c13AD *B,  X = <ld norma13AD >134rrierd="L216" cla5s="line" 5ame="L316"> 316   1347ef="D5c13 = LOAD {*A,x  X*qtation13 = >1347rier would b-bar1                           -bar2d="L216" cla5s="line" 5ame="L316"> 316   1348ef="D5c13mentation/memory-barrier13men>134Ptation/memorers.txt#L252" iiiiiiiiiiiiiiiiioers.txt#L252" iiiiiiiiiiiiiiiiid="L252" cla5s="line" 5ame="L307"> 307   13 9ef="D5c13mentation/memory-barrier13men>1349rier would bset_curr"li_statr()i            espectx286t_indicatedd="L335" cla5s="line" 5ame="L312"> 312   1355ef="D5c13mentg&quBDocume PAIRINGa13men>1350Qtation/memoooset_mb()i                     wake_up()id="L335" cla5s="line" 5ame="L312"> 312   1351ef="D5c13mentment-
 312   1352ef="D5c13mentation/memory-barrier13men>1352tation/memor""""<gentxal.2"> 3125" i -HOWTO0"""""espectcurr"li 5" istatrd="L335" cla5s="line" 5ame="L312"> 312   1353ef="D5c13 = LWnrnDda _e cos;
135rrier would bLOAD x286t_indicatedd="L335" cla5s="line" 5ame="L312"> 312   1354ef="D5c13; Y  305 (2) 5at5tru13; Y>13585" id="L285" cla5s="line" 5ame="L325"> 325   1355ef="D5c13AD *A,  STORB,  4tation/13AD >1355[Q]tToe availaxt# waketafunce" 5< snclud8id="L286" cla4s="line" 4ame="L351"> 351   1356ef="D5c13AD *B,  X = < href="D13AD >135rrierd="L216" cla5s="line" 5ame="L316"> 316   1357ef="D5c13AD *B,  STORP,  &tat13AD >13m*Qtation/memocomplete()id="L335" cla5s="line" 5ame="L312"> 312   1358ef="D5c13*A = X; Y =             13*A >1358rier would bwake_up()id="L335" cla5s="line" 5ame="L312"> 312   1359ef="D5c13*A = Y = X;












13*A >1359rier would bwake_up_all()id="L335" cla5s="line" 5ame="L312"> 312   1365ef="D5c13mentation/memory-barrier13men>1360rier would bwake_up_bit()id="L335" cla5s="line" 5ame="L312"> 312   1361ef="D5c13s spT per dependenclre a13s s>1361rier would bwake_up_in.txruptixt#()id="L335" cla5s="line" 5ame="L312"> 312   13m2ef="D5c13and  operati, Q,hat  any13and>1362rier would bwake_up_in.txruptixt#_all()id="L335" cla5s="line" 5ame="L312"> 312   1363ef="D5c13mentation/memory-barrier13men>1363rier would bwake_up_in.txruptixt#_nr()id="L335" cla5s="line" 5ame="L312"> 312   1364ef="D5c13; Y = *A;
1364rier would bwake_up_in.txruptixt#_poll()id="L335" cla5s="line" 5ame="L312"> 312   1365ef="D5c13; Y = *A;
1365rier would bwake_up_in.txruptixt#_sync()id="L335" cla5s="line" 5ame="L312"> 312   1366ef="D5c13mentation/memory-barrier13men>1366rier would bwake_up_in.txruptixt#_sync_poll()id="L335" cla5s="line" 5ame="L312"> 312   1367ef="D5c13emorBut!,,as c2 depend l13emo>1367rier would bwake_up_ricked()id="L335" cla5s="line" 5ame="L312"> 312   1368ef="D5c13e otlrede compitnces:
1368rier would bwake_up_ricked_poll()id="L335" cla5s="line" 5ame="L312"> 312   1369ef="D5c13mentation/memory-barrier13men>1369rier would bwake_up_nr()id="L335" cla5s="line" 5ame="L312"> 312   1375ef="D5c13; Y = *A;
1370rier would bwake_up_poll()id="L335" cla5s="line" 5ame="L312"> 312   1371ef="D5c13mentation/memory-barrier13men>1371rier would bwake_up_process()id="L335" cla5s="line" 5ame="L312"> 312   1372ef="D5c13mentWhilsoblem fa hrbarn13men>13;2atiod="L282" cla5s="line" 5ame="L322"> 322   1373ef="D5c13mentisn depet,Documenif 13men>13794" id="L294" cla3s="line" 3ame="L294"> 294   1374ef="D5c13mentAlphantation/memory-13men>13785" i[!] Note tive=oma#me="L3u9"> 279seimpliediby eiv sleeprtaandL iv waketado _not_d="L294" cla3s="line" 3ame="L294"> 294   1375ef="D5c13mentation/memory-barrier13men>137Ptationtat multiple etre
s bfore
 312   1376ef="D5c13s spro da _epeothenify b13s s>13;rriervaluesLts.txtdinmsleeprtahasbcalledbset_curr"li_statr().  Foxtinsiance,oifbeitd="L335" cla5s="line" 5ame="L312"> 312   1377ef="D5c13ion aetwdento then itĹion>13718" isleeprtadossid="L286" cla4s="line" 4ame="L351"> 351   13;8ef="D5c13mentation/memory-barrier13men>13789" id="L289" cla4s="line" 4ame="L279"> 279int13;9ef="D5c13 = LOAD {*A,as c1AD {*A,13 = >1379rier would bset_curr"li_statr(TASK_INTERRUPTIBLE)id="L335" cla5s="line" 5ame="L312"> 312   1385ef="D5c13 = LOAD {*A, href="Docum13 = >1380rier would btfb(x286t_indicated)d="L252" cla5s="line" 5ame="L307"> 307   1381ef="D5c13; Y = *A;
138A-API-HOWTO0"""""""""breakid="L335" cla5s="line" 5ame="L312"> 312   1382ef="D5c13AD *A,  STORB,  4tation/13AD >1382rier would b__set_curr"li_statr(TASK_RUNNING)id="L335" cla5s="line" 5ame="L312"> 312   1383ef="D5c13AD *B,  X = < href="D13AD >1383rier would bdo_sentdiung(my_demo)id="L335" cla5s="line" 5ame="L312"> 312   1384ef="D5c13AD *B,  STORP,  &tat13AD >13885" id="L285" cla5s="line" 5ame="L325"> 325   1385ef="D5c13*A = X; Y =             13*A >13816" iandL iv waketadossid="L286" cla4s="line" 4ame="L351"> 351   1386ef="D5c13*A = X; Y =             13*A >138rrierd="L216" cla5s="line" 5ame="L316"> 316   1387ef="D5c13*A = Y = X;












13*A >1387rier would bmy_demo = valueid="L335" cla5s="line" 5ame="L312"> 312   1388ef="D5c13mentation/memory-barrier13men>1388rier would bx286t_indicated = 1id="L335" cla5s="line" 5ame="L312"> 312   1389ef="D5c13ill r:
1389rier would bwake_up(&x286t_waie_qu"ue)id="L335" cla5s="line" 5ame="L312"> 312   1395ef="D5c13mentenirdn"Documilito th13men>139e8" id="L318" cla5s="line" 5ame="L338"> 338   1391ef="D5c13mentation/memory-barrier13men>13982" itore
's no3guaranteemtive=oma#changem iLx286t_indicated bee obr prtceivedibyd="L318" cla5s="line" 5ame="L338"> 338   1392ef="D5c13s offirst load reall
1392atioeiv sleeprtaasrcomioneas.txtdinmchangem iLmy_demo.  Inysusatamcir5s=siance,oeitd="L335" cla5s="line" 5ame="L312"> 312   1393ef="D5c13mentmrrierr
13294" icode  5mboie emors must in.txpoltio=iasmown#me="L3u9"> 279sebetwfng t hd="L335" cla5s="line" 5ame="L312"> 312   1394ef="D5c13atioe me-numbeive.  cer 13ati>13985" iseparaio=demo accessss.orTtusltoemabovebsleeprtaoughtm iLdoid="L286" cla4s="line" 4ame="L351"> 351   1325ef="D5c13ny elerr
erceivo"oey  su13ny >13916" id="L216" cla5s="line" 5ame="L316"> 316   1396ef="D5c13ment="DoassueB mighs bth13men>139rrier would bset_curr"li_statr(TASK_INTERRUPTIBLE)id="L335" cla5s="line" 5ame="L312"> 312   1397ef="D5c13 meme me-numbeive.bankde13 me>139*Qtation/memotfb(x286t_indicated) {d="L216" cla5s="line" 5ame="L316"> 316   1328ef="D5c13stemodd-numbeive.bankdse13ste>1398Qtation/memooooooooosmp_rmb()id="L335" cla5s="line" 5ame="L312"> 312   1399ef="D5c13the  is throold valu seq13the>1399Qtation/memooooooooodo_sentdiung(my_demo)id="L335" cla5s="line" 5ame="L312"> 312   14h5ef="D5c14h5ef is throold valu seq14h5e>1400Qtation/memo}d="L335" cla5s="line" 5ame="L312"> 312   14h1ef="D5c14hentation/memory-barrier14hen>14082" id="L282" cla3s="line" 3ame="L282"> 282VAR14h2ef="D5c14h offirst load reall
1402atioandL iv waketashouldLdoid="L286" cla4s="line" 4ame="L351"> 351   14h3ef="D5c14hentmrrierr
14094" id="L294" cla3s="line" 3ame="L294"> 294   14h4ef="D5c14htioe me-numbeive.  cer 14hti>1404rier would bmy_demo = valueid="L335" cla5s="line" 5ame="L312"> 312   14h5ef="D5c14hy elerr
erceivo"oey  su14hy >1405rier would bsmp_wmb()id="L335" cla5s="line" 5ame="L312"> 312   14h6ef="D5c14hent="DoassueB mighs bth14hen>140rrier would bx286t_indicated = 1id="L335" cla5s="line" 5ame="L312"> 312   14h7ef="D5c14hmeme me-numbeive.bankde14hme>1407rier would bwake_up(&x286t_waie_qu"ue)id="L335" cla5s="line" 5ame="L312"> 312   14h8ef="D5c14htemodd-numbeive.bankdse14hte>14089" id="L289" cla4s="line" 4ame="L279"> 279int14h9ef="D5c14hhe  is throold valu seq14hhe>1409atiod="L301" cla5s="line" 5ame="L301"> 301   1415ef="D5c14AD *B,  X = < href="D14AD >1410QtatMISCELLANEOUS FUNCTIONSd="L318" cla5s="line" 5ame="L338"> 338   1411ef="D5c14AD *B,  STORP,  1ation/m14AD >141A-API-----------------------d="L282" cla5s="line" 5ame="L322"> 322   1412ef="D5c14 = LOAD {*A,,,,,        14 = >1412atiod="L282" cla5s="line" 5ame="L322"> 322   1413ef="D5c14*A = X; Y =             14*A >14194" iOiertafunce" 5< tive=implyo2"> 322 351   14A4ef="D5c14*A = Y = X;












14*A >14185" id="L285" cla5s="line" 5ame="L325"> 325   14A5ef="D5c14mentation/memory-barrier14men>141Ptatio(*) schedule()5andLsimiltrtimplyofull.me="L3u9"> 279s.d="L294" cla3s="line" 3ame="L294"> 294   14A6ef="D5c14mentation/memory-barrier14men>141rrierd="L216" cla5s="line" 5ame="L316"> 316   1417ef="D5c14mentThrfrriers should no14men>14118" id="L318" cla5s="line" 5ame="L338"> 338   1418ef="D5c14ned rol rcu_ceivff tnce(14ned>14189" iers.txt#L252" iiiiiiiiiiiiiiiiiiid="L252" cla5s="line" 5ame="L307"> 307   14A9ef="D5c14g send load is i RCU dep14g s>14A9atioINTER--barLOCKING BARRIER EFFECTSd="L318" cla5s="line" 5ame="L338"> 338   1425ef="D5c14mentenepreplaciarriond l14men>142e8" iers.txt#L252" iiiiiiiiiiiiiiiiiiid="L252" cla5s="line" 5ame="L307"> 307   1421ef="D5c14mentation/memory-barrier14men>14282" id="L282" cla3s="line" 3ame="L282"> 282VAR1422ef="D5c14mentrol alsoa="Doc infor14men>1422atioOn SMP systemsrlockioneprimie"ve< g"vetammre
 282: ontd="L282" cla3s="line" 3ame="L282"> 282VAR1423ef="D5c14mentation/memory-barrier14men>142rriertive=doesLtsenta.me="L3uaccessmontation xn oierta-bas,owiieiny iv con.txtmofd="L282" cla3s="line" 3ame="L282"> 282VAR1424ef="D5c14mentation/memory-barrier14men>1424rierconflita.onyany particultrtlock.d="L294" cla3s="line" 3ame="L294"> 294   14m5ef="D5c14y baCONTROL DEPENDENCIEn14y b>14216" id="L216" cla5s="line" 5ame="L316"> 316   1426ef="D5c14poneument-
 316   14m7ef="D5c14mentation/memory-barrier14men>1427rierLOCKS VS MEMORY ACCESSESd="L318" cla5s="line" 5ame="L338"> 338   1428ef="D5c14ned Ay.  If the address 14ned>1428rier------------------------d="L282" cla5s="line" 5ame="L322"> 322   14m9ef="D5c14g ses should normally  m14g s>1429atiod="L301" cla5s="line" 5ame="L301"> 301   1435ef="D5c14thataodetation/memory-ba14tha>1430rierC/memory eiv followionitdinmsystem hasba pairmofaspsnricks (M)i nd (Q),5andd="L301" cla5s="line" 5ame="L301"> 301   1431ef="D5c14mentation/memory-barrier14men>14382" itoreea-bas;ltoen#shouldLoma#followion eequ" cemofax286tsboccu/id="L286" cla4s="line" 4ame="L351"> 351   1432ef="D5c14 = LOAD {*A,q,  &ata14 = >1432atiod="L282" cla5s="line" 5ame="L322"> 322   1433ef="D5c14*A = X; Y = if (p)ation/14*A >143rrier would b-bar1                           -bar2d="L216" cla5s="line" 5ame="L316"> 316   1434ef="D5c14*A = Y = X;








q,  14*A >143M[Q]tation/meers.txt#L252" iiiiiiiiiiiiiiiiioers.txt#L252" iiiiiiiiiiiiiiiiid="L252" cla5s="line" 5ame="L307"> 307   1435ef="D5c14AD *B,  X = <rrier wo14AD >143Ptation/memor*A =Lti                         *E =Leid="L335" cla5s="line" 5ame="L312"> 312   1436ef="D5c14 = LOAD {*A,x  X*qtation14 = >1436rier would bLOCK M                          LOCK Qd="L335" cla5s="line" 5ame="L312"> 312   1437ef="D5c14mentation/memory-barrier14men>143*Qtation/memo*B =Lbi                         *F =Lfid="L335" cla5s="line" 5ame="L312"> 312   1438ef="D5c14ill r:
143 2, M[3] = 3,*C =Lci                         *G =Lgid="L335" cla5s="line" 5ame="L312"> 312   1439ef="D5c14g ses should ncy is f="D14g s>1439rier would bUNLOCK M                        UNLOCK Qd="L335" cla5s="line" 5ame="L312"> 312   1445ef="D5c14 = Latas
pte compipcumic14 = >1440tation/memor*D =Ldi                         *H =Lhid="L335" cla5s="line" 5ame="L312"> 312   1441ef="D5c14 = Lct"Documesetation/me14 = >14482" id="L282" cla3s="line" 3ame="L282"> 282VAR14 2ef="D5c14mentation/memory-barrier14men>1442atioThng t hre is no3guaranteema< teiwive=ontat -bar3 bee ose
 282VAR14 3ef="D5c14 = LOAD {*A,q,  &ata14 = >144rriertirough *H occu/min, oiertativny iv constrai6tsbimposediby eiv separaio=ricksd="L282" cla3s="line" 3ame="L282"> 282VAR14 4ef="D5c14*A = X; Y = if (p)ation/14*A >14485" ion eiv separaio=-bas. Ia.might,bfoxtexample, se
id="L286" cla4s="line" 4ame="L351"> 351   1445ef="D5c14*A = X; Y =         q,  14*A >14416" id="L216" cla5s="line" 5ame="L316"> 316   1446ef="D5c14AD *B,  X = <ld norma14AD >1446rier would b*E,2LOCK M,2LOCK Q, *G,2*C,r*F,r*A,o*B,eUNLOCK Q,o*D,o*H,eUNLOCK Md="L216" cla5s="line" 5ame="L316"> 316   1447ef="D5c14 = LOAD {*A,x  X*qtation14 = >14 18" id="L318" cla5s="line" 5ame="L338"> 338   1448ef="D5c14mentation/memory-barrier14men>144PtatiButyit won'tose
 351   1449ef="D5c14mentation/memory-barrier14men>1449atiod="L301" cla5s="line" 5ame="L301"> 301   1455ef="D5c14mentg&quBDocume PAIRINGa14men>1450Qtation/memo*B,e*Cuor *D  rxcedion LOCK Md="L216" cla5s="line" 5ame="L316"> 316   1451ef="D5c14mentment-
 316   1452ef="D5c14mentation/memory-barrier14men>1452tation/memor*F,r*Guor *H  rxcedion LOCK Qd="L335" cla5s="line" 5ame="L312"> 312   1453ef="D5c14 = LWnrnDda _e cos;
145rrier would b*E,2*Fuor *G#followion UNLOCK Qd="L335" cla5s="line" 5ame="L312"> 312   1454ef="D5c14; Y  305 (2) 5at5tru14; Y>14585" id="L285" cla5s="line" 5ame="L325"> 325   1455ef="D5c14AD *A,  STORB,  4tation/14AD >14516" id="L216" cla5s="line" 5ame="L316"> 316   1456ef="D5c14AD *B,  X = < href="D14AD >145rrierHowx28r,oifbeit#followion occu/sid="L286" cla4s="line" 4ame="L351"> 351   1457ef="D5c14AD *B,  STORP,  &tat14AD >14518" id="L318" cla5s="line" 5ame="L338"> 338   1458ef="D5c14*A = X; Y =             14*A >1458rier would b-bar1                           -bar2d="L216" cla5s="line" 5ame="L316"> 316   1459ef="D5c14*A = Y = X;












14*A >1459rier would bers.txt#L252" iiiiiiiiiiiiiiiiioers.txt#L252" iiiiiiiiiiiiiiiiid="L252" cla5s="line" 5ame="L307"> 307   1465ef="D5c14mentation/memory-barrier14men>1460tation/memor*A =Ltid="L252" cla5s="line" 5ame="L307"> 307   1461ef="D5c14s spT per dependenclre a14s s>1461rier would bLOCK M          [1]d="L252" cla5s="line" 5ame="L307"> 307   1462ef="D5c14and  operati, Q,hat  any14and>1462tation/memor*B =Lbid="L335" cla5s="line" 5ame="L312"> 312   1463ef="D5c14mentation/memory-barrier14men>1463rier would b*C =Lcid="L335" cla5s="line" 5ame="L312"> 312   1464ef="D5c14; Y = *A;
146M[Q]tation/meUNLOCK M        [1]d="L252" cla5s="line" 5ame="L307"> 307   1465ef="D5c14; Y = *A;
146Ptation/memor*D =Ldi                         *E =Leid="L335" cla5s="line" 5ame="L312"> 312   1466ef="D5c14mentation/memory-barrier14men>1466rier would bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbLOCK M          [2]d="L252" cla5s="line" 5ame="L307"> 307   1467ef="D5c14emorBut!,,as c2 depend l14emo>146*Qtation/memooooooooo                        *F =Lfid="L335" cla5s="line" 5ame="L312"> 312   1468ef="D5c14e otlrede compitnces:
1468Qtation/memooooooooo                        *G =Lgid="L335" cla5s="line" 5ame="L312"> 312   1469ef="D5c14mentation/memory-barrier14men>1469Qtation/memoooooooooooooooooooooooooooooooooUNLOCK M        [2]d="L252" cla5s="line" 5ame="L307"> 307   1475ef="D5c14; Y = *A;
1470Qtation/memooooooooo                        *H =Lhid="L335" cla5s="line" 5ame="L312"> 312   1471ef="D5c14mentation/memory-barrier14men>14782" id="L282" cla3s="line" 3ame="L282"> 282VAR1472ef="D5c14mentWhilsoblem fa hrbarn14men>14;2atio-bar3 might se
id="L286" cla4s="line" 4ame="L351"> 351   1473ef="D5c14mentisn depet,Documenif 14men>14794" id="L294" cla3s="line" 3ame="L294"> 294   1474ef="D5c14mentAlphantation/memory-14men>1474rier would b*E,2LOCK M [1],2*C,r*B,t*A,eUNLOCK M [1],d="L294" cla3s="line" 3ame="L294"> 294   1475ef="D5c14mentation/memory-barrier14men>1475Qtation/memoooooooooLOCK M [2],o*H,e*F,r*G,eUNLOCK M [2],o*Dd="L294" cla3s="line" 3ame="L294"> 294   1476ef="D5c14s spro da _epeothenify b14s s>147rrierd="L216" cla5s="line" 5ame="L316"> 316   1477ef="D5c14ion aetwdento then itĺion>14718" iButyahas=ion -bar1 getsltoemrick first, -bar3 bon'tose
 351   14;8ef="D5c14mentation/memory-barrier14men>14789" id="L289" cla4s="line" 4ame="L279"> 279int14;9ef="D5c14 = LOAD {*A,as c1AD {*A,14 = >1479rier would b*B,e*C,r*D,o*F,r*Guor *H  rxcedion LOCK M [1]d="L252" cla5s="line" 5ame="L307"> 307   1485ef="D5c14 = LOAD {*A, href="Docum14 = >1480tation/memor*A,o*Buor *C#followion UNLOCK M [1]d="L252" cla5s="line" 5ame="L307"> 307   1481ef="D5c14; Y = *A;
148A-API-HOWTO0"*F,r*Guor *H  rxcedion LOCK M [2]d="L252" cla5s="line" 5ame="L307"> 307   1482ef="D5c14AD *A,  STORB,  4tation/14AD >1482tation/memor*A,o*B,e*C,r*E,2*Fuor *G#followion UNLOCK M [2]d="L252" cla5s="line" 5ame="L307"> 307   1483ef="D5c14AD *B,  X = < href="D14AD >14894" id="L294" cla3s="line" 3ame="L294"> 294   1484ef="D5c14AD *B,  STORP,  &tat14AD >14885" id="L285" cla5s="line" 5ame="L325"> 325   1485ef="D5c14*A = X; Y =             14*A >14816" iLOCKS VS I/O ACCESSESd="L318" cla5s="line" 5ame="L338"> 338   1486ef="D5c14*A = X; Y =             14*A >148rrier---------------------d="L318" cla5s="line" 5ame="L338"> 338   1487ef="D5c14*A = Y = X;












14*A >14818" id="L318" cla5s="line" 5ame="L338"> 338   1488ef="D5c14mentation/memory-barrier14men>1488rierUntat certasnmcir5s=siances (espntiallyoinvolvion NUMA),/I/O accessss 338   1489ef="D5c14ill r:
1489rierowoaspsnrickedbsece" 5< og two differ"li=-bas #L27br sfng asein.txleavediby eivd="L318" cla5s="line" 5ame="L338"> 338   1495ef="D5c14mentenirdn"Documilito th14men>149e8" iPCI bridge,7brcaus
 312   1491ef="D5c14mentation/memory-barrier14men>14982" icache-co hre cemprotocol,5andListtore
ore
 incapaxt# ofLissuion #L36requiy dd="L335" cla5s="line" 5ame="L312"> 312   1492ef="D5c14s offirst load reall
1492atioread.me="L3u9"> 279s.d="L294" cla3s="line" 3ame="L294"> 294   1493ef="D5c14mentmrrierr
14294" id="L294" cla3s="line" 3ame="L294"> 294   1494ef="D5c14atioe me-numbeive.  cer 14ati>14mM[Q]tFoxtexampleid="L286" cla4s="line" 4ame="L351"> 351   1425ef="D5c14ny elerr
erceivo"oey  su14ny >14916" id="L216" cla5s="line" 5ame="L316"> 316   1496ef="D5c14ment="DoassueB mighs bth14men>149rrier would b-bar1ooo                        -bar2d="L216" cla5s="line" 5ame="L316"> 316   1497ef="D5c14 meme me-numbeive.bankde14 me>149*Qtation/memoers.txt#L252" iiiiiiiiiiiiiiiiioers.txt#L252" iiiiiiiiiiiiiiiiid="L252" cla5s="line" 5ame="L307"> 307   1428ef="D5c14stemodd-numbeive.bankdse14ste>1498Qtation/memospsn_lock(Q)d="L252" cla5s="line" 5ame="L307"> 307   1499ef="D5c14the  is throold valu seq14the>1499Qtation/memoriersl(0, ADDR)d="L252" cla5s="line" 5ame="L307"> 307   15h5ef="D5c15h5ef is throold valu seq15h5e>1500Qtation/memoriersl(1, DATA)id="L335" cla5s="line" 5ame="L312"> 312   15h1ef="D5c15hentation/memory-barrier15hen>1501tation/memorspsn_unlock(Q)id="L335" cla5s="line" 5ame="L312"> 312   15h2ef="D5c15h offirst load reall
1502tation/memor""""""""""""""""""""""""""""""""spsn_lock(Q)id="L335" cla5s="line" 5ame="L312"> 312   15h3ef="D5c15hentmrrierr
1503tation/memor""""""""""""""""""""""""""""""""riersl(4, ADDR)id="L335" cla5s="line" 5ame="L312"> 312   15h4ef="D5c15htioe me-numbeive.  cer 15hti>1504rier would b""""""""""""""""""""""""""""""""riersl(5, DATA)id="L335" cla5s="line" 5ame="L312"> 312   15h5ef="D5c15hy elerr
erceivo"oey  su15hy >1505Qtation/memooooooooo""""""""""""""""""""""""spsn_unlock(Q)id="L335" cla5s="line" 5ame="L312"> 312   15h6ef="D5c15hent="DoassueB mighs bth15hen>150rrierd="L216" cla5s="line" 5ame="L316"> 316   15h7ef="D5c15hmeme me-numbeive.bankde15hme>1507rier#L27br sfng by eiv PCI bridge=asefollowsid="L286" cla4s="line" 4ame="L351"> 351   15h8ef="D5c15htemodd-numbeive.bankdse15hte>15089" id="L289" cla4s="line" 4ame="L279"> 279int15h9ef="D5c15hhe  is throold valu seq15hhe>1509Qtation/memoespect*ADDR = 0, espect*ADDR = 4, espect*DATA = 1, espect*DATA = 5d="L289" cla4s="line" 4ame="L279"> 279int1515ef="D5c15AD *B,  X = < href="D15AD >151e8" id="L318" cla5s="line" 5ame="L338"> 338   1511ef="D5c15AD *B,  STORP,  1ation/m15AD >151A-APIoresatwouldLprobaxty caus
 294   1512ef="D5c15 = LOAD {*A,,,,,        15 = >1512atiod="L282" cla5s="line" 5ame="L322"> 322   1513ef="D5c15*A = X; Y =             15*A >15194" id="L294" cla3s="line" 3ame="L294"> 294   15A4ef="D5c15*A = Y = X;












15*A >15185" iWive=is/necessary  hre is ceiin.txveneowiie an mmiowb() bfore
 294   15A5ef="D5c15mentation/memory-barrier15men>151Ptatispsnrick,bfoxtexampleid="L286" cla4s="line" 4ame="L351"> 351   15A6ef="D5c15mentation/memory-barrier15men>151rrierd="L216" cla5s="line" 5ame="L316"> 316   1517ef="D5c15mentThrfrriers should no15men>1517rier would b-bar1                           -bar2d="L216" cla5s="line" 5ame="L316"> 316   1518ef="D5c15ned rol rcu_ceivff tnce(15ned>151Ptation/memorers.txt#L252" iiiiiiiiiiiiiiiiioers.txt#L252" iiiiiiiiiiiiiiiiid="L252" cla5s="line" 5ame="L307"> 307   15A9ef="D5c15g send load is i RCU dep15g s>1519Qtation/memospsn_lock(Q)d="L252" cla5s="line" 5ame="L307"> 307   1525ef="D5c15mentenepreplaciarriond l15men>1520Qtation/memoriersl(0, ADDR)d="L252" cla5s="line" 5ame="L307"> 307   1521ef="D5c15mentation/memory-barrier15men>1521Qtation/memoriersl(1, DATA)id="L335" cla5s="line" 5ame="L312"> 312   1522ef="D5c15mentrol alsoa="Doc infor15men>1522tation/memormmiowb()id="L335" cla5s="line" 5ame="L312"> 312   1523ef="D5c15mentation/memory-barrier15men>152rrier would bspsn_unlock(Q)id="L335" cla5s="line" 5ame="L312"> 312   1524ef="D5c15mentation/memory-barrier15men>1524rier would b""""""""""""""""""""""""""""""""spsn_lock(Q)id="L335" cla5s="line" 5ame="L312"> 312   15m5ef="D5c15y baCONTROL DEPENDENCIEn15y b>1525Qtation/memooooooooo""""""""""""""""""""""""riersl(4, ADDR)id="L335" cla5s="line" 5ame="L312"> 312   1526ef="D5c15poneument-
 312   15m7ef="D5c15mentation/memory-barrier15men>152*Qtation/memooooooooo                        mmiowb()id="L335" cla5s="line" 5ame="L312"> 312   1528ef="D5c15ned Ay.  If the address 15ned>1528Qtation/memooooooooo                        spsn_unlock(Q)id="L335" cla5s="line" 5ame="L312"> 312   1529ef="D5c15g ses should normally  m15g s>1529atiod="L301" cla5s="line" 5ame="L301"> 301   1535ef="D5c15thataodetation/memory-ba15tha>1530Qtateiis bee oensure tive 301   1531ef="D5c15mentation/memory-barrier15men>15382" ibfore
 294   1532ef="D5c15 = LOAD {*A,q,  &ata15 = >1532atiod="L282" cla5s="line" 5ame="L322"> 322   1533ef="D5c15*A = X; Y = if (p)ation/15*A >15394" id="L294" cla3s="line" 3ame="L294"> 294   1534ef="D5c15*A = Y = X;








q,  15*A >153M[Q]tFuriertmre
,#followion a#stre
 by a/load 312   1535ef="D5c15AD *B,  X = <rrier wo15AD >153Ptatifoxtoma#mmiowb(),7brcaus
 312   1536ef="D5c15 = LOAD {*A,x  X*qtation15 = >1536rieris perfoxmedid="L286" cla4s="line" 4ame="L351"> 351   1537ef="D5c15mentation/memory-barrier15men>15318" id="L318" cla5s="line" 5ame="L338"> 338   1538ef="D5c15ill r:
1538rier would b-bar1                           -bar2d="L216" cla5s="line" 5ame="L316"> 316   1539ef="D5c15g ses should ncy is f="D15g s>1539rier would bers.txt#L252" iiiiiiiiiiiiiiiiioers.txt#L252" iiiiiiiiiiiiiiiiid="L252" cla5s="line" 5ame="L307"> 307   1545ef="D5c15 = Latas
pte compipcumic15 = >1540tation/memorspsn_lock(Q)d="L252" cla5s="line" 5ame="L307"> 307   1541ef="D5c15 = Lct"Documesetation/me15 = >1541Qtation/memoriersl(0, ADDR)d="L252" cla5s="line" 5ame="L307"> 307   15 2ef="D5c15mentation/memory-barrier15men>1542tation/memoro = readl(DATA)id="L335" cla5s="line" 5ame="L312"> 312   15 3ef="D5c15 = LOAD {*A,q,  &ata15 = >154rrier would bspsn_unlock(Q)id="L335" cla5s="line" 5ame="L312"> 312   15 4ef="D5c15*A = X; Y = if (p)ation/15*A >1544rier would b""""""""""""""""""""""""""""""""spsn_lock(Q)id="L335" cla5s="line" 5ame="L312"> 312   1545ef="D5c15*A = X; Y =         q,  15*A >1545Qtation/memooooooooo""""""""""""""""""""""""riersl(4, ADDR)id="L335" cla5s="line" 5ame="L312"> 312   1546ef="D5c15AD *B,  X = <ld norma15AD >1546rier would bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb = readl(DATA)id="L335" cla5s="line" 5ame="L312"> 312   15 7ef="D5c15 = LOAD {*A,x  X*qtation15 = >154*Qtation/memooooooooo                        spsn_unlock(Q)id="L335" cla5s="line" 5ame="L312"> 312   15 8ef="D5c15mentation/memory-barrier15men>15489" id="L289" cla4s="line" 4ame="L279"> 279int1549ef="D5c15mentation/memory-barrier15men>1549atiod="L301" cla5s="line" 5ame="L301"> 301   1555ef="D5c15mentg&quBDocume PAIRINGa15men>1550QtatSee la5s="line" 5ala5Book/deviceiobook.tmplbfoxtmre
 infoxmae" 5.d="L294" cla3s="line" 3ame="L294"> 294   1551ef="D5c15mentment-
 282VAR1552ef="D5c15mentation/memory-barrier15men>1552atiod="L282" cla5s="line" 5ame="L322"> 322   1553ef="D5c15 = LWnrnDda _e cos;
155rrierers.txt#L252" iiiiiiiiiiiiiiiiiiid="L252" cla5s="line" 5ame="L307"> 307   1554ef="D5c15; Y  305 (2) 5at5tru15; Y>15585" iWHERE ARE MEMORY BARRIERS NEEDED?d="L252" cla5s="line" 5ame="L307"> 307   1555ef="D5c15AD *A,  STORB,  4tation/15AD >15516" iers.txt#L252" iiiiiiiiiiiiiiiiiiid="L252" cla5s="line" 5ame="L307"> 307   1556ef="D5c15AD *B,  X = < href="D15AD >155rrierd="L216" cla5s="line" 5ame="L316"> 316   1557ef="D5c15AD *B,  STORP,  &tat15AD >15518" iUntat noxmal operne" 5,.me="L3uoperne" 5 reontation is gentxallyLnot/goion #od="L216" cla5s="line" 5ame="L316"> 316   1558ef="D5c15*A = X; Y =             15*A >1558rierbetamproblem asba sionle-toreaded     ar piecemofacode bee ostee o ppear #od="L216" cla5s="line" 5ame="L316"> 316   1559ef="D5c15*A = Y = X;












15*A >1559rierworkacorrectly,.x286oifbit's inyan SMP kernel.orTtre
 ae
,#howx28r,ofourd="L216" cla5s="line" 5ame="L316"> 316   1565ef="D5c15mentation/memory-barrier15men>1560taticir5s=siances inyoresatreontation definersly _could_ betamproblemid="L286" cla4s="line" 4ame="L351"> 351   1561ef="D5c15s spT per dependenclre a15s s>15682" id="L282" cla3s="line" 3ame="L282"> 282VAR1562ef="D5c15and  operati, Q,hat  any15and>1562tatio(*) In.txprocessoxtin.txace" 5.d="L294" cla3s="line" 3ame="L294"> 294   1563ef="D5c15mentation/memory-barrier15men>15694" id="L294" cla3s="line" 3ame="L294"> 294   1564ef="D5c15; Y = *A;
156M[Q]ta(*) Atomicuoperne" 5s.d="L294" cla3s="line" 3ame="L294"> 294   1565ef="D5c15; Y = *A;
15616" id="L216" cla5s="line" 5ame="L316"> 316   1566ef="D5c15mentation/memory-barrier15men>1566rier (*) Accession devices.d="L294" cla3s="line" 3ame="L294"> 294   1567ef="D5c15emorBut!,,as c2 depend l15emo>15618" id="L318" cla5s="line" 5ame="L338"> 338   1568ef="D5c15e otlrede compitnces:
1568Qtati(*) In.txrupts.d="L294" cla3s="line" 3ame="L294"> 294   1569ef="D5c15mentation/memory-barrier15men>1569atiod="L301" cla5s="line" 5ame="L301"> 301   1575ef="D5c15; Y = *A;
157e8" id="L318" cla5s="line" 5ame="L338"> 338   1571ef="D5c15mentation/memory-barrier15men>15782" iINTERPROCESSOR INTERACTIONd="L318" cla5s="line" 5ame="L338"> 338   1572ef="D5c15mentWhilsoblem fa hrbarn15men>15;2atio--------------------------d="L318" cla5s="line" 5ame="L338"> 338   1573ef="D5c15mentisn depet,Documenif 15men>15794" id="L294" cla3s="line" 3ame="L294"> 294   1574ef="D5c15mentAlphantation/memory-15men>15785" iWing t hre's amsystem wiie mre
 312   1575ef="D5c15mentation/memory-barrier15men>1575Qtatsystem #L27br workion xn oma#s

q demo set ve 312   1576ef="D5c15s spro da _epeothenify b15s s>157rriersynchronisne" 5 problems,aandL iv usual way of dealion wiie  ivm is ceius
d="L335" cla5s="line" 5ame="L312"> 312   1577ef="D5c15ion aetwdento then itĻion>15718" iricks.orLicks,#howx28r,oae
 316   15;8ef="D5c15mentation/memory-barrier15men>15789" ioperneeowiieoutL iv usemofaamrick tfb t ve opossixt#.  Inysusatamcas
d="L335" cla5s="line" 5ame="L312"> 312   1579ef="D5c15 = LOAD {*A,as c1AD {*A,15 = >1579rieroperne" 5s tive 312   1585ef="D5c15 = LOAD {*A, href="Docum15 = >1580tatiaLmalfunce" 5.d="L294" cla3s="line" 3ame="L294"> 294   1581ef="D5c15; Y = *A;
15882" id="L282" cla3s="line" 3ame="L282"> 282VAR1582ef="D5c15AD *A,  STORB,  4tation/15AD >1582tatiC/memory,bfoxtexample,  iv R/W semaphre
 282VAR1583ef="D5c15AD *B,  X = < href="D15AD >15894" iqu"ued xn oma#semaphre
, by virtu# ofLit7havion a#piecemofaiasmsiack  &lked ced="L282" cla3s="line" 3ame="L282"> 282VAR1584ef="D5c15AD *B,  STORP,  &tat15AD >15885" ioma#semaphre
's listmofbwaieioneprocessssid="L286" cla4s="line" 4ame="L351"> 351   1585ef="D5c15*A = X; Y =             15*A >15816" id="L216" cla5s="line" 5ame="L316"> 316   1586ef="D5c15*A = X; Y =             15*A >158rrier would bstruta.rw_semaphre
<{d="L216" cla5s="line" 5ame="L316"> 316   1587ef="D5c15*A = Y = X;












15*A >158*Qtation/memooooooooo...d="L294" cla3s="line" 3ame="L294"> 294   1588ef="D5c15mentation/memory-barrier15men>1588Qtation/memooooooooospsnrick_tmrickid="L335" cla5s="line" 5ame="L312"> 312   1589ef="D5c15ill r:
1589Qtation/memooooooooostruta.list_head.waie12 312   1595ef="D5c15mentenirdn"Documilito th15men>1590Qtation/memo}id="L335" cla5s="line" 5ame="L312"> 312   1591ef="D5c15mentation/memory-barrier15men>15982" id="L282" cla3s="line" 3ame="L282"> 282VAR1592ef="D5c15s offirst load reall
1592rier would bstruta.rwsem_waie12<{d="L216" cla5s="line" 5ame="L316"> 316   1593ef="D5c15mentmrrierr
1593tation/memor""""""""struta.list_head.listid="L335" cla5s="line" 5ame="L312"> 312   1594ef="D5c15atioe me-numbeive.  cer 15ati>1594rier would b""""""""struta.task_struta.*taskid="L335" cla5s="line" 5ame="L312"> 312   1595ef="D5c15ny elerr
erceivo"oey  su15ny >1595Qtation/memo}id="L335" cla5s="line" 5ame="L312"> 312   1596ef="D5c15ment="DoassueB mighs bth15men>159rrierd="L216" cla5s="line" 5ame="L316"> 316   1597ef="D5c15 meme me-numbeive.bankde15 me>159*QtatTobwake upba particultrtwaie12,  iv up_read()uor up_riers()ufunce" 5< hav
 ceid="L286" cla4s="line" 4ame="L351"> 351   1528ef="D5c15stemodd-numbeive.bankdse15ste>15989" id="L289" cla4s="line" 4ame="L279"> 279int1599ef="D5c15the  is throold valu seq15the>1599Qtati(1) readltoemnextopoin.tx 279int16h5ef="D5c16h5ef is throold valu seq16h5e>1600Qtation/mnextowaie12 312   16h1ef="D5c16hentation/memory-barrier16hen>16082" id="L282" cla3s="line" 3ame="L282"> 282VAR16h2ef="D5c16h offirst load reall
1602tatio(2) readltoempoin.tx 312   16h3ef="D5c16hentmrrierr
16094" id="L294" cla3s="line" 3ame="L294"> 294   16h4ef="D5c16htioe me-numbeive.  cer 16hti>1604rier (3)oe ear # hrtask"poin.tx 312   16h5ef="D5c16hy elerr
erceivo"oey  su16hy >16016" id="L216" cla5s="line" 5ame="L316"> 316   16h6ef="D5c16hent="DoassueB mighs bth16hen>160rrier (4)bcallbwake_up_process() xn oma#taski5andd="L301" cla5s="line" 5ame="L301"> 301   16h7ef="D5c16hmeme me-numbeive.bankde16hme>16018" id="L318" cla5s="line" 5ame="L338"> 338   16h8ef="D5c16htemodd-numbeive.bankdse16hte>1608Qtati(5) re eas
 294   16h9ef="D5c16hhe  is throold valu seq16hhe>1609atiod="L301" cla5s="line" 5ame="L301"> 301   1615ef="D5c16AD *B,  X = < href="D16AD >161e8" iIn oiertawonts,Lit7haseceiperfoxm/omis eequ" cemofax286tsid="L286" cla4s="line" 4ame="L351"> 351   1611ef="D5c16AD *B,  STORP,  1ation/m16AD >16182" id="L282" cla3s="line" 3ame="L282"> 282VAR1612ef="D5c16 = LOAD {*A,,,,,        16 = >1612rier would bLOAD#waie12->list.nextid="L335" cla5s="line" 5ame="L312"> 312   1613ef="D5c16*A = X; Y =             16*A >1613rier would bLOAD#waie12->taskid="L335" cla5s="line" 5ame="L312"> 312   16A4ef="D5c16*A = Y = X;












16*A >1614rier would bespectwaie12->taskid="L335" cla5s="line" 5ame="L312"> 312   16A5ef="D5c16mentation/memory-barrier16men>1615Qtation/memoCALLbwakeupd="L335" cla5s="line" 5ame="L312"> 312   16A6ef="D5c16mentation/memory-barrier16men>161rrier would bRELEASE taskd="L335" cla5s="line" 5ame="L312"> 312   16A7ef="D5c16mentThrfrriers should no16men>16118" id="L318" cla5s="line" 5ame="L338"> 338   1618ef="D5c16ned rol rcu_ceivff tnce(16ned>161PtatiandLif 338   1619ef="D5c16g send load is i RCU dep16g s>1619Qtatmalfunce" 5.d="L294" cla3s="line" 3ame="L294"> 294   1625ef="D5c16mentenepreplaciarriond l16men>162e8" id="L318" cla5s="line" 5ame="L338"> 338   1621ef="D5c16mentation/memory-barrier16men>1621QtatO cemit7hasequ"ued itself5andLdropped oma#semaphre
 rick,b iv waie12LdoesLnotd="L318" cla5s="line" 5ame="L338"> 338   1622ef="D5c16mentrol alsoa="Doc infor16men>1622tatigetltoemrick again;mit7insieadljust waiesbfoxtiesbtask"poin.tx 312   1623ef="D5c16mentation/memory-barrier16men>162rrierbfore
 312   1624ef="D5c16mentation/memory-barrier16men>1624rierifbeit#task"poin.tx 294   16m5ef="D5c16y baCONTROL DEPENDENCIEn16y b>16216" ianoierta-ba might starteprocession #L36waie12LandLmight clobbry eiv waie12'sd="L294" cla3s="line" 3ame="L294"> 294   16m6ef="D5c16poneument-
 294   1627ef="D5c16mentation/memory-barrier16men>16218" id="L318" cla5s="line" 5ame="L338"> 338   1628ef="D5c16ned Ay.  If the address 16ned>1628QtatC/memory eivniwive=might h ppen 351   1629ef="D5c16g ses should normally  m16g s>1629atiod="L301" cla5s="line" 5ame="L301"> 301   1635ef="D5c16thataodetation/memory-ba16tha>1630Qtation/memo-bar1                           -bar2d="L216" cla5s="line" 5ame="L316"> 316   1631ef="D5c16mentation/memory-barrier16men>1631Qtation/memoers.txt#L252" iiiiiiiiiiiiiiiiioers.txt#L252" iiiiiiiiiiiiiiiiid="L252" cla5s="line" 5ame="L307"> 307   1632ef="D5c16 = LOAD {*A,q,  &ata16 = >1632tation/memor""""""""""""""""""""""""""""""""down_xxx()d="L252" cla5s="line" 5ame="L307"> 307   1633ef="D5c16*A = X; Y = if (p)ation/16*A >1633tation/memor""""""""""""""""""""""""""""""""Qu"ue waie12d="L252" cla5s="line" 5ame="L307"> 307   1634ef="D5c16*A = Y = X;








q,  16*A >1634rier would b""""""""""""""""""""""""""""""""Sleepd="L252" cla5s="line" 5ame="L307"> 307   1635ef="D5c16AD *B,  X = <rrier wo16AD >163Ptation/memorup_yyy()d="L252" cla5s="line" 5ame="L307"> 307   1636ef="D5c16 = LOAD {*A,x  X*qtation16 = >1636rier would bLOAD#waie12->taskid="L335" cla5s="line" 5ame="L312"> 312   1637ef="D5c16mentation/memory-barrier16men>163*Qtation/memoespectwaie12->taskid="L335" cla5s="line" 5ame="L312"> 312   1638ef="D5c16ill r:
1638Qtation/memooooooooo                        Woken 312   1639ef="D5c16g ses should ncy is f="D16g s>1639rier would b<preempt>d="L335" cla5s="line" 5ame="L312"> 312   1645ef="D5c16 = Latas
pte compipcumic16 = >1640Qtation/memooooooooo                        Ress="eprocessiond="L335" cla5s="line" 5ame="L312"> 312   1641ef="D5c16 = Lct"Documesetation/me16 = >1641Qtation/memooooooooooooooooooooooooooooooooodown_xxx()ireturnsd="L294" cla3s="line" 3ame="L294"> 294   16 2ef="D5c16mentation/memory-barrier16men>1642tation/memor""""""""""""""""""""""""""""""""callbfoo()d="L252" cla5s="line" 5ame="L307"> 307   16 3ef="D5c16 = LOAD {*A,q,  &ata16 = >1643tation/memor""""""""""""""""""""""""""""""""foo() clobbrys *waie12d="L252" cla5s="line" 5ame="L307"> 307   16 4ef="D5c16*A = X; Y = if (p)ation/16*A >1644rier would b</preempt>d="L335" cla5s="line" 5ame="L312"> 312   1645ef="D5c16*A = X; Y =         q,  16*A >1645Qtation/memoLOAD#waie12->list.nextid="L335" cla5s="line" 5ame="L312"> 312   1646ef="D5c16AD *B,  X = <ld norma16AD >1646rier would b--- OOPS ---d="L318" cla5s="line" 5ame="L338"> 338   16 7ef="D5c16 = LOAD {*A,x  X*qtation16 = >16 18" id="L318" cla5s="line" 5ame="L338"> 338   16 8ef="D5c16mentation/memory-barrier16men>16489" iTtisecouldLbe dealt wiie usion #L36semaphre
 rick,bbutL ivny iv down_xxx()d="L252" cla5s="line" 5ame="L307"> 307   1649ef="D5c16mentation/memory-barrier16men>1649atiofunce" 5 hasbteine dlessly getltoemspsnrick again afe12Lbeion woken 294   1655ef="D5c16mentg&quBDocume PAIRINGa16men>165e8" id="L318" cla5s="line" 5ame="L338"> 338   1651ef="D5c16mentment-
 338id="L286" cla4s="line" 4ame="L351"> 351   1652ef="D5c16mentation/memory-barrier16men>1652atiod="L282" cla5s="line" 5ame="L322"> 322   1653ef="D5c16 = LWnrnDda _e cos;
1653rier would bLOAD#waie12->list.nextid="L335" cla5s="line" 5ame="L312"> 312   1654ef="D5c16; Y  305 (2) 5at5tru16; Y>1654rier would bLOAD#waie12->taskid="L335" cla5s="line" 5ame="L312"> 312   1655ef="D5c16AD *A,  STORB,  4tation/16AD >1655Qtation/memosmp_mb()id="L335" cla5s="line" 5ame="L312"> 312   1656ef="D5c16AD *B,  X = < href="D16AD >1656Qtation/memoespectwaie12->taskid="L335" cla5s="line" 5ame="L312"> 312   1657ef="D5c16AD *B,  STORP,  &tat16AD >1657rier would b-ALLbwakeupd="L335" cla5s="line" 5ame="L312"> 312   1658ef="D5c16*A = X; Y =             16*A >1658rier would bRELEASE taskd="L335" cla5s="line" 5ame="L312"> 312   1659ef="D5c16*A = Y = X;












16*A >1659atiod="L301" cla5s="line" 5ame="L301"> 301   1665ef="D5c16mentation/memory-barrier16men>166e8" iIn ttisecase,  iv 1"> 301 makesba guaranteemtive 301   1661ef="D5c16s spT per dependenclre a16s s>16682" i1"> 301 wee o ppear #o h ppen 301d="L301" cla5s="line" 5ame="L301"> 301   1662ef="D5c16and  operati, Q,hat  any16and>1662tatiwiie respntt 301   1663ef="D5c16mentation/memory-barrier16men>16635" ioma#me="L3uaccessss 301 wee obr complete by eiv timeL iv 1"> 301d="L301" cla5s="line" 5ame="L301"> 301   1664ef="D5c16; Y = *A;
166M[Q]tinsiruta" 5 itself5isecomplete.d="L294" cla3s="line" 3ame="L294"> 294   1665ef="D5c16; Y = *A;
16616" id="L216" cla5s="line" 5ame="L316"> 316   1666ef="D5c16mentation/memory-barrier16men>1666rierOn a UP system -iwiee
 316   1667ef="D5c16emorBut!,,as c2 depend l16emo>16618" icompil12Lb"> 316,  ius #Lkion sure tir compil12Lemitsltoeminsiruta" 5srig t hd="L335" cla5s="line" 5ame="L312"> 312   1668ef="D5c16e otlrede compitnces:
1668Qtatright ontat wiieoutLactuallyoin.txvenion in oma#-ba. bei cema he
's only=ontd="L282" cla3s="line" 3ame="L282"> 282VAR1669ef="D5c16mentation/memory-barrier16men>1669atio-ba,mtive<-ba's dependencymontation logic wee otake cae
mofax28ry#iung else.d="L294" cla3s="line" 3ame="L294"> 294   1675ef="D5c16; Y = *A;
167e8" id="L318" cla5s="line" 5ame="L338"> 338   1671ef="D5c16mentation/memory-barrier16men>16782" id="L282" cla3s="line" 3ame="L282"> 282VAR1672ef="D5c16mentWhilsoblem fa hrbarn16men>16;2atioATOMIC OPERATIONSd="L318" cla5s="line" 5ame="L338"> 338   1673ef="D5c16mentisn depet,Documenif 16men>16794" i-----------------d="L318" cla5s="line" 5ame="L338"> 338   1674ef="D5c16mentAlphantation/memory-16men>16785" id="L285" cla5s="line" 5ame="L325"> 325   1675ef="D5c16mentation/memory-barrier16men>1675QtatWhilstltoeyoae
 325   1676ef="D5c16s spro da _epeothenify b16s s>167rrieroperne" 5s ae
 279s5andd="L301" cla5s="line" 5ame="L301"> 301   1677ef="D5c16ion aetwdento then itļion>16718" isome don't,bbutL ivy'e
<28ry heavily relied xn asba group tiroughoutL ivd="L301" cla5s="line" 5ame="L301"> 301   1678ef="D5c16mentation/memory-barrier16men>16789" ikernel.d="L301" cla5s="line" 5ame="L301"> 301   1679ef="D5c16 = LOAD {*A,as c1AD {*A,16 = >1679atiod="L301" cla5s="line" 5ame="L301"> 301   1685ef="D5c16 = LOAD {*A, href="Docum16 = >1680tatiAny atomicuoperne" 5 tive 301   1681ef="D5c16; Y = *A;
16882" iaboutL iv sttio=(old xr new)bimpliesban SMP-condie" 5al gentxal me="L3u9"> 279d="L301" cla5s="line" 5ame="L301"> 301   1682ef="D5c16AD *A,  STORB,  4tation/16AD >1682tati(smp_mb()) xn each smoraofaoma#actualuoperne" 5 (wiie  iv excepe" 5 ofd="L301" cla5s="line" 5ame="L301"> 301   1683ef="D5c16AD *B,  X = < href="D16AD >16894" iexplicitmrickuoperne" 5s, described  tior).orTtrs
 includeid="L286" cla4s="line" 4ame="L351"> 351   1684ef="D5c16AD *B,  STORP,  &tat16AD >16885" id="L285" cla5s="line" 5ame="L325"> 325   1685ef="D5c16*A = X; Y =             16*A >1685Qtation/memoxchg()id="L335" cla5s="line" 5ame="L312"> 312   1686ef="D5c16*A = X; Y =             16*A >168rrier would bcmpxchg()id="L335" cla5s="line" 5ame="L312"> 312   1687ef="D5c16*A = Y = X;












16*A >168*Qtation/memoatomic_cmpxchg()id="L335" cla5s="line" 5ame="L312"> 312   1688ef="D5c16mentation/memory-barrier16men>1688Qtation/memoatomic_inc_return()id="L335" cla5s="line" 5ame="L312"> 312   1689ef="D5c16ill r:
1689Qtation/memoatomic_dec_return()id="L335" cla5s="line" 5ame="L312"> 312   1695ef="D5c16mentenirdn"Documilito th16men>1690Qtation/memoatomic_add_return()id="L335" cla5s="line" 5ame="L312"> 312   1691ef="D5c16mentation/memory-barrier16men>1691Qtation/memoatomic_sub_return()id="L335" cla5s="line" 5ame="L312"> 312   1692ef="D5c16s offirst load reall
1692rier would batomic_inc_and_test()id="L335" cla5s="line" 5ame="L312"> 312   1693ef="D5c16mentmrrierr
1693tation/memoratomic_dec_and_test()id="L335" cla5s="line" 5ame="L312"> 312   1694ef="D5c16atioe me-numbeive.  cer 16ati>1694rier would batomic_sub_and_test()id="L335" cla5s="line" 5ame="L312"> 312   1695ef="D5c16ny elerr
erceivo"oey  su16ny >1695Qtation/memoatomic_add_negne"ve()id="L335" cla5s="line" 5ame="L312"> 312   1696ef="D5c16ment="DoassueB mighs bth16men>169rrier would batomic_add_unless()i    /*iwienysusceeds (returns 1) */d="L335" cla5s="line" 5ame="L312"> 312   1697ef="D5c16 meme me-numbeive.bankde16 me>169*Qtation/memotest_and_set_bit()id="L335" cla5s="line" 5ame="L312"> 312   1698ef="D5c16stemodd-numbeive.bankdse16ste>1698Qtation/memotest_and_c ear_bit()id="L335" cla5s="line" 5ame="L312"> 312   1699ef="D5c16the  is throold valu seq16the>1699Qtation/memotest_and_change_bit()id="L335" cla5s="line" 5ame="L312"> 312   17h5ef="D5c17h5ef is throold valu seq17h5e>170e8" id="L318" cla5s="line" 5ame="L338"> 338   17h1ef="D5c17hentation/memory-barrier17hen>17082" iTivs
 ae
 used 338   17h2ef="D5c17h offirst load reall
1702tatioperne" 5s andiadjustion 35"ere cemcoun.txs cewards objntt 338   17h3ef="D5c17hentmrrierr
17094" isusat#iebimplicitmme="L3u9"> 279 esentas ae
 301   17h4ef="D5c17htioe me-numbeive.  cer 17hti>17085" id="L285" cla5s="line" 5ame="L325"> 325   17h5ef="D5c17hy elerr
erceivo"oey  su17hy >17016" id="L216" cla5s="line" 5ame="L316"> 316   17h6ef="D5c17hent="DoassueB mighs bth17hen>170rrierTiv followion operne" 5s ae
 316   17h7ef="D5c17hmeme me-numbeive.bankde17hme>17018" i6"> 316<,bbutLmight b
 used 338   17h8ef="D5c17htemodd-numbeive.bankdse17hte>1708tatioperne" 5sid="L286" cla4s="line" 4ame="L351"> 351   17h9ef="D5c17hhe  is throold valu seq17hhe>1709atiod="L301" cla5s="line" 5ame="L301"> 301   1715ef="D5c17AD *B,  X = < href="D17AD >1710Qtation/memoatomic_set()id="L335" cla5s="line" 5ame="L312"> 312   1711ef="D5c17AD *B,  STORP,  1ation/m17AD >1711tation/memorset_bit()id="L335" cla5s="line" 5ame="L312"> 312   1712ef="D5c17 = LOAD {*A,,,,,        17 = >1712rier would bc ear_bit()id="L335" cla5s="line" 5ame="L312"> 312   1713ef="D5c17*A = X; Y =             17*A >1713rier would bchange_bit()id="L335" cla5s="line" 5ame="L312"> 312   17A4ef="D5c17*A = Y = X;












17*A >17185" id="L285" cla5s="line" 5ame="L325"> 325   17A5ef="D5c17mentation/memory-barrier17men>1715QtatWiie  ivs
 279 shouldLbe used 325   17A6ef="D5c17mentation/memory-barrier17men>171rrier(smp_mb__bfore
_c ear_bit() 301   17A7ef="D5c17mentThrfrriers should no17men>17118" id="L318" cla5s="line" 5ame="L338"> 338   1718ef="D5c17ned rol rcu_ceivff tnce(17ned>17189" id="L289" cla4s="line" 4ame="L279"> 279int1719ef="D5c17g send load is i RCU dep17g s>1719QtatTiv followion alsoodoL_not_ implyome="L3 6"> 316<,bandLsoL#L27requiy  explicitd="L289" cla4s="line" 4ame="L279"> 279int1725ef="D5c17mentenepreplaciarriond l17men>172e8" ime="L3u9"> 279s5untat some cir5s=siances (smp_mb__bfore
_atomic_dec() 279int1721ef="D5c17mentation/memory-barrier17men>1721Qtatinsiance)id="L286" cla4s="line" 4ame="L351"> 351   1722ef="D5c17mentrol alsoa="Doc infor17men>1722atiod="L282" cla5s="line" 5ame="L322"> 322   1723ef="D5c17mentation/memory-barrier17men>1723tation/memoratomic_add()id="L335" cla5s="line" 5ame="L312"> 312   1724ef="D5c17mentation/memory-barrier17men>1724rier would batomic_sub()id="L335" cla5s="line" 5ame="L312"> 312   1725ef="D5c17y baCONTROL DEPENDENCIEn17y b>1725Qtation/memoatomic_inc()id="L335" cla5s="line" 5ame="L312"> 312   1726ef="D5c17poneument-
 312   1727ef="D5c17mentation/memory-barrier17men>17218" id="L318" cla5s="line" 5ame="L338"> 338   1728ef="D5c17ned Ay.  If the address 17ned>1728QtatIfL ivy'e
 316   1729ef="D5c17g ses should normally  m17g s>1729atio6"> 316<,bunless t hre's amcouplion betweng sine"sticaludata.d="L301" cla5s="line" 5ame="L301"> 301   1735ef="D5c17thataodetation/memory-ba17tha>173e8" id="L318" cla5s="line" 5ame="L338"> 338   1731ef="D5c17mentation/memory-barrier17men>1731QtatIfL ivy'e
 294   1732ef="D5c17 = LOAD {*A,q,  &ata17 = >1732tati ivyLprobaxty don'tine dome="L3u9"> 279s5brcaus
 294   1733ef="D5c17*A = X; Y = if (p)ation/17*A >1733tatiwee obr adjusted 301   1734ef="D5c17*A = Y = X;








q,  17*A >1734riersuffici"lir35"ere ces< iLmak
 279 unnecessary.d="L301" cla5s="line" 5ame="L301"> 301   1735ef="D5c17AD *B,  X = <rrier wo17AD >17316" id="L216" cla5s="line" 5ame="L316"> 316   1736ef="D5c17 = LOAD {*A,x  X*qtation17 = >1736rierIfL ivy'e
 316   1737ef="D5c17mentation/memory-barrier17men>173*Qtatdoine dome="L3u9"> 279s5asba rickupr"mie"ve gentxallyLhasbteidot#iungs in ad="L216" cla5s="line" 5ame="L316"> 316   1738ef="D5c17ill r:
1738Qtatspntificuontat.d="L301" cla5s="line" 5ame="L301"> 301   1739ef="D5c17g ses should ncy is f="D17g s>1739atiod="L301" cla5s="line" 5ame="L301"> 301   1745ef="D5c17 = Latas
pte compipcumic17 = >1740QtatBasically, each usageecaseLhasbteibr cae
fully=consmoryed a< teiwieiertame="L3d="L216" cla5s="line" 5ame="L316"> 316   1741ef="D5c17 = Lct"Documesetation/me17 = >17482" i1"> 301s ae
 294   17 2ef="D5c17mentation/memory-barrier17men>1742atiod="L282" cla5s="line" 5ame="L322"> 322   17 3ef="D5c17 = LOAD {*A,q,  &ata17 = >1743tatiTiv followion operne" 5s ae
 351   17 4ef="D5c17*A = X; Y = if (p)ation/17*A >17485" id="L285" cla5s="line" 5ame="L325"> 325   1745ef="D5c17*A = X; Y =         q,  17*A >1745Qtation/memotest_and_set_bit_lock()id="L335" cla5s="line" 5ame="L312"> 312   1746ef="D5c17AD *B,  X = <ld norma17AD >1746rier would bc ear_bit_unlock()id="L335" cla5s="line" 5ame="L312"> 312   1747ef="D5c17 = LOAD {*A,x  X*qtation17 = >174*Qtation/memo__c ear_bit_unlock()id="L335" cla5s="line" 5ame="L312"> 312   1748ef="D5c17mentation/memory-barrier17men>17489" id="L289" cla4s="line" 4ame="L279"> 279int1749ef="D5c17mentation/memory-barrier17men>1749QtatTivseyimple="li LOCK-ationuandiUNLOCK-ationuoperne" 5s.rTtrs
 shouldLbe used 301   1755ef="D5c17mentg&quBDocume PAIRINGa17men>175e8" ip35"ere cemteioiertaoperne" 5s wienyimple="liion rickionepr"mie"ves,7brcaus
d="L301" cla5s="line" 5ame="L301"> 301   1751ef="D5c17mentment-
 294   1752ef="D5c17mentation/memory-barrier17men>1752atiod="L282" cla5s="line" 5ame="L322"> 322   1753ef="D5c17 = LWnrnDda _e cos;
1753rier[!] Notemtive 279 pr"mie"ves ae
 301   1754ef="D5c17; Y  305 (2) 5at5tru17; Y>1754riersitune" 5s brcaus
 301   1755ef="D5c17AD *A,  STORB,  4tation/17AD >1755Qtat6"> 316<,bandLsoL9"> 279 insiruta" 5srae
 294   1756ef="D5c17AD *B,  X = < href="D17AD >1756QtatandLinysusatcasesltoemspntial 9"> 279 pr"mie"ves wee obr no-ops.d="L294" cla3s="line" 3ame="L294"> 294   1757ef="D5c17AD *B,  STORP,  &tat17AD >17518" id="L318" cla5s="line" 5ame="L338"> 338   1758ef="D5c17*A = X; Y =             17*A >1758rierSee la5s="line" 5aatomic_ops.a> bfoxtmre
 infoxmae" 5.d="L294" cla3s="line" 3ame="L294"> 294   1759ef="D5c17*A = Y = X;












17*A >1759atiod="L301" cla5s="line" 5ame="L301"> 301   1765ef="D5c17mentation/memory-barrier17men>176e8" id="L318" cla5s="line" 5ame="L338"> 338   1761ef="D5c17s spT per dependenclre a17s s>17682" iACCESSING DEVICESd="L318" cla5s="line" 5ame="L338"> 338   1762ef="D5c17and  operati, Q,hat  any17and>1762atio-----------------d="L318" cla5s="line" 5ame="L338"> 338   1763ef="D5c17mentation/memory-barrier17men>17694" id="L294" cla3s="line" 3ame="L294"> 294   1764ef="D5c17; Y = *A;
176M[Q]tMany devices can be me="L3um pped,bandLsoL ppear #o oma#-ba aseifL ivy'e
 294   1765ef="D5c17; Y = *A;
17616" io set of me="L3uricne" 5s.r Teicontroltsusatamdevice,  iv dr"ver usuallyLhasbted="L294" cla3s="line" 3ame="L294"> 294   1766ef="D5c17mentation/memory-barrier17men>1766riermak
 301   1767ef="D5c17emorBut!,,as c2 depend l17emo>17618" id="L318" cla5s="line" 5ame="L338"> 338   1768ef="D5c17e otlrede compitnces:
1768QtatHowx28r,ohavion a#c evrta-ba oxta#c evrtacompil12Lcreatesla 338   1769ef="D5c17mentation/memory-barrier17men>1769atioin tive 301   1775ef="D5c17; Y = *A;
177e8" ideviceminy iv requisers.ontat ifbeit#-ba oxttir compil12L#iunksmit7istmre
d="L301" cla5s="line" 5ame="L301"> 301   1771ef="D5c17mentation/memory-barrier17men>17782" ieffici"lirceireontat,lcombmor oxtmergeuaccessss<- some#iung tive 312   1772ef="D5c17mentWhilsoblem fa hrbarn17men>1772tati iv devicem iLmalfunce" 5.d="L294" cla3s="line" 3ame="L294"> 294   1773ef="D5c17mentisn depet,Documenif 17men>17794" id="L294" cla3s="line" 3ame="L294"> 294   1774ef="D5c17mentAlphantation/memory-17men>17785" iInsmoraofaoma#Linux kernel, I/O shouldLbe donemtirough 279int1775ef="D5c17mentation/memory-barrier17men>1775Qtatrouiioss<- susatas 279int1776ef="D5c17s spro da _epeothenify b17s s>177rrierappropr"ately=sequ" iial.r Whilstltois, foxtoma#mostlpart,irentats  iv explicitd="L289" cla4s="line" 4ame="L279"> 279int1777ef="D5c17ion aetwdento then itĽion>17718" iusemofame="L3u9"> 279s5unnecessary, t hre ae
 301   1778ef="D5c17mentation/memory-barrier17men>17789" imight b
 neededid="L286" cla4s="line" 4ame="L351"> 351   1779ef="D5c17 = LOAD {*A,as c1AD {*A,17 = >1779atiod="L301" cla5s="line" 5ame="L301"> 301   1785ef="D5c17 = LOAD {*A, href="Docum17 = >1780tatii(1) On some systems, I/O stre
s ae
 301   1781ef="D5c17; Y = *A;
1781tation/mesoLfoxt_ae _ gentxal dr"vers ricks shouldLbe used 312   1782ef="D5c17AD *A,  STORB,  4tation/17AD >1782rier woulissued pr"or #o unlockion #L36ciericalusece" 5.d="L294" cla3s="line" 3ame="L294"> 294   1783ef="D5c17AD *B,  X = < href="D17AD >17894" id="L294" cla3s="line" 3ame="L294"> 294   1784ef="D5c17AD *B,  STORP,  &tat17AD >1784rier (2) Ifaoma#accessoxtfunce" 5< ae
 used 294   1785ef="D5c17*A = X; Y =             17*A >1785Qtation/mrelax dome="L3uaccessuproperties,7 ivny_mandatory_ome="L3u9"> 279s5ae
d="L301" cla5s="line" 5ame="L301"> 301   1786ef="D5c17*A = X; Y =             17*A >178rrier woulrequiy d 294   1787ef="D5c17*A = Y = X;












17*A >17818" id="L318" cla5s="line" 5ame="L338"> 338   1788ef="D5c17mentation/memory-barrier17men>1788rierSee la5s="line" 5aDa5Book/deviceiobook.tmplbfoxtmre
 infoxmae" 5.d="L294" cla3s="line" 3ame="L294"> 294   1789ef="D5c17ill r:
1789atiod="L301" cla5s="line" 5ame="L301"> 301   1795ef="D5c17mentenirdn"Documilito th17men>179e8" id="L318" cla5s="line" 5ame="L338"> 338   1791ef="D5c17mentation/memory-barrier17men>17982" iINTERRUPTSd="L318" cla5s="line" 5ame="L338"> 338   1792ef="D5c17s offirst load reall
1792atio----------d="L318" cla5s="line" 5ame="L338"> 338   1793ef="D5c17mentmrrierr
17994" id="L294" cla3s="line" 3ame="L294"> 294   1794ef="D5c17atioe me-numbeive.  cer 17ati>1794rierA dr"ver #L27br in.txrupt d 301   1795ef="D5c17ny elerr
erceivo"oey  su17ny >1795Qtattwolpartsaofaoma#dr"ver #L27in.tx"ere wiie each oiert's attempts 279int1796ef="D5c17ment="DoassueB mighs bth17men>179rrieraccessu iv device.d="L294" cla3s="line" 3ame="L294"> 294   1797ef="D5c17 meme me-numbeive.bankde17 me>17918" id="L318" cla5s="line" 5ame="L338"> 338   1798ef="D5c17stemodd-numbeive.bankdse17ste>17989" iTtise#L27br all0v"ated -ive< east7inlpart -ibytdisablion ricaluin.txrupts (ad="L216" cla5s="line" 5ame="L316"> 316   1799ef="D5c17the  is throold valu seq17the>1799Qtatfoxm/ofalockion), susat#ive 301   18h5ef="D5c18h5ef is throold valu seq18h5e>180e8" itoemin.txrupt-disabledbsece" 5 301   18h1ef="D5c18hentation/memory-barrier18hen>18082" irouiios7istexecuiiog,ltov dr"ver's cre
 #L27not"run xn oma#s

q -ba,mandLitsd="L289" cla4s="line" 4ame="L279"> 279int18h2ef="D5c18h offirst load reall
1802tatiin.txruptuisLnotipermitt d 279int18h3ef="D5c18hentmrrierr
18094" ihandled,b ius  ivrin.txruptuhandle2LdoesLnotine doceirick againstltoaa.d="L294" cla3s="line" 3ame="L294"> 294   18h4ef="D5c18htioe me-numbeive.  cer 18hti>18085" id="L285" cla5s="line" 5ame="L325"> 325   18h5ef="D5c18hy elerr
erceivo"oey  su18hy >18016" iHowx28r,oconsmorytamdr"ver tive 279int18h6ef="D5c18hent="DoassueB mighs bth18hen>180rrieraddressuregise12LandLa demo regise12.  Ifmtive 279int18h7ef="D5c18hmeme me-numbeive.bankde18hme>18018" iuntat in.txrupt-disable="li andL ivnltov dr"ver's in.txruptuhandle2Lis invokedid="L286" cla4s="line" 4ame="L351"> 351   18h8ef="D5c18htemodd-numbeive.bankdse18hte>18089" id="L289" cla4s="line" 4ame="L279"> 279int18h9ef="D5c18hhe  is throold valu seq18hhe>1809Qtation/memoLOCAL IRQ DISABLEd="L289" cla4s="line" 4ame="L279"> 279int1815ef="D5c18AD *B,  X = < href="D18AD >1810Qtation/memoriersw(ADDR, 3)id="L335" cla5s="line" 5ame="L312"> 312   1811ef="D5c18AD *B,  STORP,  1ation/m18AD >1811tation/memorriersw(DATA, y)id="L335" cla5s="line" 5ame="L312"> 312   1812ef="D5c18 = LOAD {*A,,,,,        18 = >1812rier would bLOCAL IRQ ENABLEd="L289" cla4s="line" 4ame="L279"> 279int1813ef="D5c18*A = X; Y =             18*A >1813rier would b<in.txrupt>d="L335" cla5s="line" 5ame="L312"> 312   18A4ef="D5c18*A = Y = X;












18*A >1814rier would briersw(ADDR, 4)id="L335" cla5s="line" 5ame="L312"> 312   1815ef="D5c18mentation/memory-barrier18men>1815Qtation/memoq =ireadw(DATA)id="L335" cla5s="line" 5ame="L312"> 312   1816ef="D5c18mentation/memory-barrier18men>181rrier would b</in.txrupt>d="L335" cla5s="line" 5ame="L312"> 312   18A7ef="D5c18mentThrfrriers should no18men>18118" id="L318" cla5s="line" 5ame="L338"> 338   1818ef="D5c18ned rol rcu_ceivff tnce(18ned>1818tatiTiv stre
 #o oma#demo regise12=might h ppen 338   1819ef="D5c18g send load is i RCU dep18g s>1819Qtataddressuregise12Lifmontation rulesrae
 351   1825ef="D5c18mentenepreplaciarriond l18men>182e8" id="L318" cla5s="line" 5ame="L338"> 338   1821ef="D5c18mentation/memory-barrier18men>1821tation/memorespect*ADDR =i3,respect*ADDR =i4,respect*DATA =iy,oq =iLOAD#*DATAd="L318" cla5s="line" 5ame="L338"> 338   1822ef="D5c18mentrol alsoa="Doc infor18men>1822atiod="L282" cla5s="line" 5ame="L322"> 322   1823ef="D5c18mentation/memory-barrier18men>18294" id="L294" cla3s="line" 3ame="L294"> 294   1824ef="D5c18mentation/memory-barrier18men>1824rierIfmontation rulesrae
 279int1825ef="D5c18y baCONTROL DEPENDENCIEn18y b>1825Qtatin.txruptudisabledbsece" 5<#L27 eak outsmoraofaii andL#L27in.tx eave wiied="L294" cla3s="line" 3ame="L294"> 294   1826ef="D5c18poneument-
 279int1827ef="D5c18mentation/memory-barrier18men>18218" iexplicitm1"> 301s ae
 294   1828ef="D5c18ned Ay.  If the address 18ned>18289" id="L289" cla4s="line" 4ame="L279"> 279int1829ef="D5c18g ses should normally  m18g s>1829atioNoxmally 279int1835ef="D5c18thataodetation/memory-ba18tha>183e8" isece" 5s wee oinclude synchronous loaduoperne" 5s xn strictly 279int1831ef="D5c18mentation/memory-barrier18men>1831Qtatregise12s tive foxm/implicitmI/O 9"> 279 279int1832ef="D5c18 = LOAD {*A,q,  &ata18 = >1832tatimmiowb()umL27ne doceibe used 301   1833ef="D5c18*A = X; Y = if (p)ation/18*A >18394" id="L294" cla3s="line" 3ame="L294"> 294   1834ef="D5c18*A = Y = X;








q,  18*A >18385" id="L285" cla5s="line" 5ame="L325"> 325   1835ef="D5c18AD *B,  X = <rrier wo18AD >18316" iA similtrtsitune" 5umL27occu/ betweng an in.txrupturouiios7andL wourouiiossd="L289" cla4s="line" 4ame="L279"> 279int1836ef="D5c18 = LOAD {*A,x  X*qtation18 = >1836rierrunnion xn separate -bas a ve communicate wiie each oiert/ IfmsusatamcaseLisd="L289" cla4s="line" 4ame="L279"> 279int1837ef="D5c18mentation/memory-barrier18men>183*Qtatlikely,7 ivnyin.txrupt-disablion ricks shouldLbe used 294   1838ef="D5c18ill r:
18389" id="L289" cla4s="line" 4ame="L279"> 279int1839ef="D5c18g ses should ncy is f="D18g s>1839atiod="L301" cla5s="line" 5ame="L301"> 301   1845ef="D5c18 = Latas
pte compipcumic18 = >1840Qtatxt#L252" iiiiiiiiiiiiiiiiid="L252" cla5s="line" 5ame="L307"> 307   1841ef="D5c18 = Lct"Documesetation/me18 = >18482" iKERNELmI/O BARRIER EFFECTSd="L318" cla5s="line" 5ame="L338"> 338   18 2ef="D5c18mentation/memory-barrier18men>1842atioxt#L252" iiiiiiiiiiiiiiiiid="L252" cla5s="line" 5ame="L307"> 307   1843ef="D5c18 = LOAD {*A,q,  &ata18 = >18494" id="L294" cla3s="line" 3ame="L294"> 294   18 4ef="D5c18*A = X; Y = if (p)ation/18*A >18485" iWivnlaccession I/O me="L3, dr"vers shouldLus
 279int1845ef="D5c18*A = X; Y =         q,  18*A >1845Qtatfunce" 5 351   1846ef="D5c18AD *B,  X = <ld norma18AD >1846rierd="L286" cla4s="line" 4ame="L351"> 351   1847ef="D5c18 = LOAD {*A,x  X*qtation18 = >184*Qtati(*)yinX(), outX()id="L286" cla4s="line" 4ame="L351"> 351   1848ef="D5c18mentation/memory-barrier18men>18489" id="L289" cla4s="line" 4ame="L279"> 279int1849ef="D5c18mentation/memory-barrier18men>1849Qtation/mTivs
 ae
 in.tnded 279int1855ef="D5c18mentg&quBDocume PAIRINGa18men>1850Qtation/ma ve's pr"marily a -ba-spntificuconcepe.rTtr i3867andLx86_64 processoxs 279int1851ef="D5c18mentment-
 301   1852ef="D5c18mentation/memory-barrier18men>1852rier woul-bas don'tihave susatamconcepe.d="L301" cla5s="line" 5ame="L301"> 301   1853ef="D5c18 = LWnrnDda _e cos;
18594" id="L294" cla3s="line" 3ame="L294"> 294   1854ef="D5c18; Y  305 (2) 5at5tru18; Y>1854rier woulTtr PCIbbus,5amongst oierts, defioss 279int1855ef="D5c18AD *A,  STORB,  4tation/18AD >1855Qtation/m-bas as 279int1856ef="D5c18AD *B,  X = < href="D18AD >1856Qtation/mspace.  Howx28r,oit7mL27alsoobe m pped5asba virtualuI/O spacemin oma#-ba'sd="L294" cla3s="line" 3ame="L294"> 294   1857ef="D5c18AD *B,  STORP,  &tat18AD >1857rier woulme="L3um p,lparticultrly=on omose -bas a ve don'tisupport7al.txnate I/Od="L289" cla4s="line" 4ame="L279"> 279int1858ef="D5c18*A = X; Y =             18*A >1858rier woulspaces.d="L294" cla3s="line" 3ame="L294"> 294   1859ef="D5c18*A = Y = X;












18*A >1859atiod="L301" cla5s="line" 5ame="L301"> 301   1865ef="D5c18mentation/memory-barrier18men>1860Qtation/mAccessss<#o omis spacem#L27br fully=synchronous (as xn i386),bbutd="L289" cla4s="line" 4ame="L279"> 279int1861ef="D5c18s spT per dependenclre a18s s>1861tation/mein.txmediaL3u9ridges (susatas 279int1862ef="D5c18and  operati, Q,hat  any18and>1862Qtation/ma ve.d="L294" cla3s="line" 3ame="L294"> 294   1863ef="D5c18mentation/memory-barrier18men>18694" id="L294" cla3s="line" 3ame="L294"> 294   1864ef="D5c18; Y = *A;
1864rier woulTtryoae
 294   1865ef="D5c18; Y = *A;
18616" id="L216" cla5s="line" 5ame="L316"> 316   1866ef="D5c18mentation/memory-barrier18men>1866rier woulTtryoae
 301   1867ef="D5c18emorBut!,,as c2 depend l18emo>1867rier woulme="L3uandLI/O operne" 5/d="L294" cla3s="line" 3ame="L294"> 294   1868ef="D5c18e otlrede compitnces:
18689" id="L289" cla4s="line" 4ame="L279"> 279int1869ef="D5c18mentation/memory-barrier18men>1869atioi(*)yreadX(), riersX()id="L286" cla4s="line" 4ame="L351"> 351   1875ef="D5c18; Y = *A;
187e8" id="L318" cla5s="line" 5ame="L338"> 338   1871ef="D5c18mentation/memory-barrier18men>1871tation/meWieiertativs
 ae
 guaranteedoceibe fully=ontated andLuncombmord wiied="L294" cla3s="line" 3ame="L294"> 294   1872ef="D5c18mentWhilsoblem fa hrbarn18men>1872Qtation/mrespntt 294   1873ef="D5c18mentisn depet,Documenif 18men>1873rier wouldefiosd foxtoma#me="L3uwindow tirough 294   1874ef="D5c18mentAlphantation/memory-18men>1874rier wouli3867architetaure #Lchines, foxtexample,  iis is controll d 294   1875ef="D5c18mentation/memory-barrier18men>1875Qtation/mMTRRuregise12s.d="L294" cla3s="line" 3ame="L294"> 294   1876ef="D5c18s spro da _epeothenify b18s s>1876rierd="L286" cla4s="line" 4ame="L351"> 351   1877ef="D5c18ion aetwdento then itľion>1877rier woulOrdinarily,ativs
 wee obr guaranteedoceibe fully=ontated andLuncombmord,d="L294" cla3s="line" 3ame="L294"> 294   1878ef="D5c18mentation/memory-barrier18men>1878rier woulprovided 294   1879ef="D5c18 = LOAD {*A,as c1AD {*A,18 = >1879atiod="L301" cla5s="line" 5ame="L301"> 301   1885ef="D5c18 = LOAD {*A, href="Docum18 = >1880Qtation/mHowx28r,oin.txmediaL3uhaxdwae
 (susatas 301   1881ef="D5c18; Y = *A;
1881tation/medeftxxal ifaii soowisivs;oceiflusatamstre
,ba riad from oma#s

q ricne" 5d="L301" cla5s="line" 5ame="L301"> 301   1882ef="D5c18AD *A,  STORB,  4tation/18AD >1882rier woulismpreferted[*],bbutLa riad from oma#s

q devicemoxtfrom configurne" 5d="L301" cla5s="line" 5ame="L301"> 301   1883ef="D5c18AD *B,  X = < href="D18AD >1883rier woulspace shouldLsuffic# foxtPCI.d="L294" cla3s="line" 3ame="L294"> 294   1884ef="D5c18AD *B,  STORP,  &tat18AD >18885" id="L285" cla5s="line" 5ame="L325"> 325   1885ef="D5c18*A = X; Y =             18*A >1885Qtation/m[*] NOTE! attemption #eiriad from oma#s

q ricne" 5tas 325   1886ef="D5c18*A = X; Y =             18*A >188rrier would b caus
 ammalfunce" 5 -oconsmorytoma#16550 Rx/Txuserial regise12s ford="L289" cla4s="line" 4ame="L279"> 279int1887ef="D5c18*A = Y = X;












18*A >188*Qtation/memotexample.d="L294" cla3s="line" 3ame="L294"> 294   1888ef="D5c18mentation/memory-barrier18men>18889" id="L289" cla4s="line" 4ame="L279"> 279int1889ef="D5c18ill r:
1889Qtation/mUsed wiie prefetchaxt# I/O me="L3, ag mmiowb()u9"> 279m#L27br requiy d 279int1895ef="D5c18mentenirdn"Documilito th18men>1890Qtation/mfoxcemstre
s ceibe ontated.d="L294" cla3s="line" 3ame="L294"> 294   1891ef="D5c18mentation/memory-barrier18men>18982" id="L282" cla3s="line" 3ame="L282"> 282VAR1892ef="D5c18s offirst load reall
1892rier woulP easeireftx 294   1893ef="D5c18mentmrrierr
1893tation/mebetweng PCIbtransace" 5s.d="L294" cla3s="line" 3ame="L294"> 294   1894ef="D5c18atioe me-numbeive.  cer 18ati>18985" id="L285" cla5s="line" 5ame="L325"> 325   1895ef="D5c18ny elerr
erceivo"oey  su18ny >1895Qtati(*)yreadX_relax d()d="L285" cla5s="line" 5ame="L325"> 325   1896ef="D5c18ment="DoassueB mighs bth18men>1896rierd="L286" cla4s="line" 4ame="L351"> 351   1897ef="D5c18 meme me-numbeive.bankde18 me>189*Qtation/mTivs
 ae
 similtrtceireadX(), butLae
 325   1898ef="D5c18stemodd-numbeive.bankdse18ste>1898Qtation/mway. B
 awae
 #ive 279mavailnxt#.d="L294" cla3s="line" 3ame="L294"> 294   1899ef="D5c18the  is throold valu seq18the>1899atiod="L301" cla5s="line" 5ame="L301"> 301   19h5ef="D5c19h5ef is throold valu seq19h5e>1900Qtati(*)yioreadX(), iowiersX()d="L301" cla5s="line" 5ame="L301"> 301   19h1ef="D5c19hentation/memory-barrier19hen>19082" id="L282" cla3s="line" 3ame="L282"> 282VAR19h2ef="D5c19h offirst load reall
1902Qtation/mTivs
 wee operfoxm appropr"ately=foxtoma#typebofaaccessu ivy'e
 282VAR19h3ef="D5c19hentmrrierr
1903rier wouldoiog,lbr ityinX()/outX() ory35adX()/wiersX().d="L294" cla3s="line" 3ame="L294"> 294   19h4ef="D5c19htioe me-numbeive.  cer 19hti>19085" id="L285" cla5s="line" 5ame="L325"> 325   19h5ef="D5c19hy elerr
erceivo"oey  su19hy >19016" id="L216" cla5s="line" 5ame="L316"> 316   19h6ef="D5c19hent="DoassueB mighs bth19hen>190rrierxt#L252" iiiiiiiiiiiiiiiiiiiiiiiiiiiiiiid="L252" cla5s="line" 5ame="L307"> 307   19h7ef="D5c19hmeme me-numbeive.bankde19hme>19018" iASSUMED MINIMUM EXECUTION ORDERING MODELd="L252" cla5s="line" 5ame="L307"> 307   19h8ef="D5c19htemodd-numbeive.bankdse19hte>19089" ixt#L252" iiiiiiiiiiiiiiiiiiiiiiiiiiiiiiid="L252" cla5s="line" 5ame="L307"> 307   19h9ef="D5c19hhe  is throold valu seq19hhe>1909atiod="L301" cla5s="line" 5ame="L301"> 301   1915ef="D5c19AD *B,  X = < href="D19AD >1910QtatItLhasbteibr ions="dmtive 301   1911ef="D5c19AD *B,  STORP,  1ation/m19AD >1911tatimaintaol 301   1912ef="D5c19 = LOAD {*A,,,,,        19 = >1912tati(susatas 279int1913ef="D5c19*A = X; Y =             19*A >1913rierfrv),bandLsoLoma#mostlrelax docaseL(    ly=DEC Alpha)7must b
 ions="dmoutsmord="L289" cla4s="line" 4ame="L279"> 279int1914ef="D5c19*A = Y = X;












19*A >1914rierofaarch-spntificucod#.d="L294" cla3s="line" 3ame="L294"> 294   1915ef="D5c19mentation/memory-barrier19men>19116" id="L216" cla5s="line" 5ame="L316"> 316   1916ef="D5c19mentation/memory-barrier19men>19169" iTtise#eansL ive 316   1917ef="D5c19mentThrfrriers should no19men>19118" isiream i5ian2.ontat it feelsbliket- xr evvnyinlparall0lt- provided 279int1918ef="D5c19ned rol rcu_ceivff tnce(19ned>1918tatiinsiruta" 5min oma#siream depends xn an earli79 insiruta" 5,5 ivny iatd="L289" cla4s="line" 4ame="L279"> 279int1919ef="D5c19g send load is i RCU dep19g s>1919Qtatearli79 insiruta" 5ymust b
 suffici"lily complete[*] bfore
 294   1925ef="D5c19mentenepreplaciarriond l19men>192e8" iinsiruta" 5ymay proceed;min oiert wonts: provided 294   1921ef="D5c19mentation/memory-barrier19men>1921taticausality ise#Lintaoldd.d="L294" cla3s="line" 3ame="L294"> 294   1922ef="D5c19mentrol alsoa="Doc infor19men>1922atiod="L282" cla5s="line" 5ame="L322"> 322   1923ef="D5c19mentation/memory-barrier19men>1923tatio[*] Some insiruta" 5srhave mre
 322   1924ef="D5c19mentation/memory-barrier19men>1924rier woulcondia" 5ycod#s, 279int1925ef="D5c19y baCONTROL DEPENDENCIEn19y b>1925Qtation/minsiruta" 5srmay depend xn dif"ere t esentas.d="L294" cla3s="line" 3ame="L294"> 294   1926ef="D5c19poneument-
 351   1927ef="D5c19mentation/memory-barrier19men>19218" iA -ba mL27alsoodiscaedman2.insiruta" 5ysequ" ce tive 279int1928ef="D5c19ned Ay.  If the address 19ned>19289" iultimate esenta.  Foxtexample, ifbewo adjacelirinsiruta" 5srboieiriad agd="L289" cla4s="line" 4ame="L279"> 279int1929ef="D5c19g ses should normally  m19g s>1929atioimmediate valu
 in.o oma#s

q regise12,ltov firstm#L27br discaeddd.d="L294" cla3s="line" 3ame="L294"> 294   1935ef="D5c19thataodetation/memory-ba19tha>193e8" id="L318" cla5s="line" 5ame="L338"> 338   1931ef="D5c19mentation/memory-barrier19men>19382" id="L282" cla3s="line" 3ame="L282"> 282VAR1932ef="D5c19 = LOAD {*A,q,  &ata19 = >1932tatiSimiltrly,aitLhasbteibr ions="dmtive 316   1933ef="D5c19*A = X; Y = if (p)ation/19*A >19394" isiream i5ian2.waybii sees fit, 316   1934ef="D5c19*A = Y = X;








q,  19*A >19385" i#Lintaoldd.d="L294" cla3s="line" 3ame="L294"> 294   1935ef="D5c19AD *B,  X = <rrier wo19AD >19316" id="L216" cla5s="line" 5ame="L316"> 316   1936ef="D5c19 = LOAD {*A,x  X*qtation19 = >1936rierd="L286" cla4s="line" 4ame="L351"> 351   1937ef="D5c19mentation/memory-barrier19men>193*Qtatiiiiiiiiiiiiiiiiiiiiiiiiiiiid="L252" cla5s="line" 5ame="L307"> 307   1938ef="D5c19ill r:
19389" iTHE EFFECTS OF THE -ba CACHEd="L289" cla4s="line" 4ame="L279"> 279int1939ef="D5c19g ses should ncy is f="D19g s>1939atioiiiiiiiiiiiiiiiiiiiiiiiiiiiid="L252" cla5s="line" 5ame="L307"> 307   1945ef="D5c19 = Latas
pte compipcumic19 = >194e8" id="L318" cla5s="line" 5ame="L338"> 338   1941ef="D5c19 = Lct"Documesetation/me19 = >19482" iTtr waybcach dome="L3uoperne" 5s ae
 279int19 2ef="D5c19mentation/memory-barrier19men>1942atioa certaol 279int19 3ef="D5c19 = LOAD {*A,q,  &ata19 = >19494" ime="L3ucohere cemsystem  ive<#Lintaols 294   19 4ef="D5c19*A = X; Y = if (p)ation/19*A >19485" id="L285" cla5s="line" 5ame="L325"> 325   1945ef="D5c19*A = X; Y =         q,  19*A >1945QtatAs fartas 325   1946ef="D5c19AD *B,  X = <ld norma19AD >1946riercach sLgoes,7 iv me="L3usystem hasbteiinclude oma#-ba's cach s, and me="L3d="L285" cla5s="line" 5ame="L325"> 325   1947ef="D5c19 = LOAD {*A,x  X*qtation19 = >194*Qtat1"> 301s foxtoma#mostlpart 325   1948ef="D5c19mentation/memory-barrier19men>19489" i(me="L3u1"> 301s logically 351   1949ef="D5c19mentation/memory-barrier19men>1949atiod="L301" cla5s="line" 5ame="L301"> 301   1955ef="D5c19mentg&quBDocume PAIRINGa19men>1950Qtation/memooooo<---#-ba --->/memooooo:emooooo<----------- Me="L3u----------->d="L335" cla5s="line" 5ame="L312"> 312   1951ef="D5c19mentment-
 351   1952ef="D5c19mentation/memory-barrier19men>1952rier would b+--------+ld b+--------+ld:d b+--------+ld b+-----------+d="L286" cla4s="line" 4ame="L351"> 351   1953ef="D5c19 = LWnrnDda _e cos;
1953rier would b| would b| wou| would b| w:d b| would b| wou| would bwou| wou+--------+d="L286" cla4s="line" 4ame="L351"> 351   1954ef="D5c19; Y  305 (2) 5at5tru19; Y>1954rier would b| w-ba  b| wou| Me="L3u| w:d b| -ba  bb| wou| would bwou| wou| would b|d="L286" cla4s="line" 4ame="L351"> 351   1955ef="D5c19AD *A,  STORB,  4tation/19AD >1955rier would b| w-re
< |--->|mAccess |----->|mCach < |<-->|mwould bwou| wou| would b|d="L286" cla4s="line" 4ame="L351"> 351   1956ef="D5c19AD *B,  X = < href="D19AD >1956rier would b| would b| wou| Queue b| w:d b| would b| wou| would bwou|--->|mMe="L3u|d="L286" cla4s="line" 4ame="L351"> 351   1957ef="D5c19AD *B,  STORP,  &tat19AD >1957rier would b| would b| wou| would b| w:d b| would b| wou| would bwou| wou| would b|d="L286" cla4s="line" 4ame="L351"> 351   1958ef="D5c19*A = X; Y =             19*A >1958rier woul  b+--------+ld b+--------+ld:d b+--------+ld b| would bwou| wou| would b|d="L286" cla4s="line" 4ame="L351"> 351   1959ef="D5c19*A = Y = X;












19*A >1959Qtation/memoooooooooooooooooooooooooooiooooooooooooooooo|mCach < wou| wou+--------+d="L286" cla4s="line" 4ame="L351"> 351   1965ef="D5c19mentation/memory-barrier19men>1960Qtation/memoooooooooooooooooooooooooooiooooooooooooooooo|mCohere c3u|d="L286" cla4s="line" 4ame="L351"> 351   1961ef="D5c19s spT per dependenclre a19s s>1961Qtation/memoooooooooooooooooooooooooooiooooooooooooooooo|mMechanismu| wou+--------+d="L286" cla4s="line" 4ame="L351"> 351   1962ef="D5c19and  operati, Q,hat  any19and>1962rier would b+--------+ld b+--------+ld:d b+--------+ld b| would bwou| wou| would b|d="L286" cla4s="line" 4ame="L351"> 351   1963ef="D5c19mentation/memory-barrier19men>1963rier would b| would b| wou| would b| w:d b| would b| wou| would bwou| wou| would b|d="L286" cla4s="line" 4ame="L351"> 351   1964ef="D5c19; Y = *A;
1964rier would b| w-ba  b| wou| Me="L3u| w:d b| -ba  bb| wou| would bwou|--->|mDevicem|d="L286" cla4s="line" 4ame="L351"> 351   1965ef="D5c19; Y = *A;
1965rier would b| w-re
< |--->|mAccess |----->|mCach < |<-->|mwould bwou| wou| would b|d="L286" cla4s="line" 4ame="L351"> 351   1966ef="D5c19mentation/memory-barrier19men>1966rier would b| would b| wou| Queue b| w:d b| would b| wou| would bwou| wou| would b|d="L286" cla4s="line" 4ame="L351"> 351   1967ef="D5c19emorBut!,,as c2 depend l19emo>1967rier would b| would b| wou| would b| w:d b| would b| wou| would bwou| wou+--------+d="L286" cla4s="line" 4ame="L351"> 351   1968ef="D5c19e otlrede compitnces:
1968rier woul  b+--------+ld b+--------+ld:d b+--------+ld b+-----------+d="L286" cla4s="line" 4ame="L351"> 351   1969ef="D5c19mentation/memory-barrier19men>1969Qtation/memoooooooooooooooooooooooooooid="L286" cla4s="line" 4ame="L351"> 351   1975ef="D5c19; Y = *A;
1970Qtation/memoooooooooooooooooooooooooooid="L286" cla4s="line" 4ame="L351"> 351   1971ef="D5c19mentation/memory-barrier19men>19782" id="L282" cla3s="line" 3ame="L282"> 282VAR1972ef="D5c19mentWhilsoblem fa hrbarn19men>1972QtatAlthough 325   1973ef="D5c19mentisn depet,Documenif 19men>1973rier-ba cive 294   1974ef="D5c19mentAlphantation/memory-19men>1974rieritywee Lstee L ppear aseifL ivofull.me="L3aaccessuhadutakng placemas fartas 294   1975ef="D5c19mentation/memory-barrier19men>1975Qtatoiert -bas arr concerldd si cemoma#cach ucohere cy.mechanisms wee omigrate ttrd="L294" cla3s="line" 3ame="L294"> 294   1976ef="D5c19s spro da _epeothenify b19s s>1976riercach emormovtx 294   1977ef="D5c19ion aetwdento then itĿion>19718" id="L318" cla5s="line" 5ame="L338"> 338   1978ef="D5c19mentation/memory-barrier19men>1978tatiTiv -ba cre
 #L27execuietinsiruta" 5sri5ian2.ontat it deems fit, 338   1979ef="D5c19 = LOAD {*A,as c1AD {*A,19 = >1979atioexpnta d 338   1985ef="D5c19 = LOAD {*A, href="Docum19 = >1980Qtatgentxateiriad agdLstre
 operne" 5s wiesat ivn go in.o oma#queue ofame="L3d="L318" cla5s="line" 5ame="L338"> 338   1981ef="D5c19; Y = *A;
1981tatiaccessss<#o be 338   1982ef="D5c19AD *A,  STORB,  4tation/19AD >1982rieritywesh s, and continuetexecuiion un.i oit7istfoxcedoceiwai bfoxtan insiruta" 5d="L216" cla5s="line" 5ame="L316"> 316   1983ef="D5c19AD *B,  X = < href="D19AD >1983rierceicomplete.d="L294" cla3s="line" 3ame="L294"> 294   1984ef="D5c19AD *B,  STORP,  &tat19AD >19885" id="L285" cla5s="line" 5ame="L325"> 325   1985ef="D5c19*A = X; Y =             19*A >1985QtatWive<#e="L3u1"> 301s arr concerldd wiie is controllion #L36ontat in wiesad="L285" cla5s="line" 5ame="L325"> 325   1986ef="D5c19*A = X; Y =             19*A >198rrieraccessss 301   1987ef="D5c19*A = Y = X;












19*A >198*Qtat#L36ontat in wiesa ttr esentas ae
 301   1988ef="D5c19mentation/memory-barrier19men>1988tatiin oma#system.d="L294" cla3s="line" 3ame="L294"> 294   1989ef="D5c19ill r:
1989atiod="L301" cla5s="line" 5ame="L301"> 301   1995ef="D5c19mentenirdn"Documilito th19men>1990Qtat[!] Me="L3u1"> 301s arr _not_ needed wiiei5 a givng -ba,tas<-bas always seed="L301" cla5s="line" 5ame="L301"> 301   1991ef="D5c19mentation/memory-barrier19men>19982" iomair own riads agdLstre
s aseifL ivyuhaduh ppened i5iprogram ontat.d="L301" cla5s="line" 5ame="L301"> 301   1992ef="D5c19s offirst load reall
1992atiod="L282" cla5s="line" 5ame="L322"> 322   1993ef="D5c19mentmrrierr
1993tati[!] MMIOuorLoiert devicemaccessss<#L27bypaonuoma#cach usystem.ulTtis depends xnd="L282" cla5s="line" 5ame="L322"> 322   1994ef="D5c19atioe me-numbeive.  cer 19ati>19985" ioma#properties ofaoma#me="L3uwindow tirough 279int1995ef="D5c19ny elerr
erceivo"oey  su19ny >1995Qtatthe usebofaany spntial devicemcommunicat" 5minsiruta" 5sroma#-ba mL27have.d="L301" cla5s="line" 5ame="L301"> 301   1996ef="D5c19ment="DoassueB mighs bth19men>1996rierd="L286" cla4s="line" 4ame="L351"> 351   1997ef="D5c19 meme me-numbeive.bankde19 me>19918" id="L318" cla5s="line" 5ame="L338"> 338   1998ef="D5c19stemodd-numbeive.bankdse19ste>1998QtatCACHE COHERENCYd="L318" cla5s="line" 5ame="L338"> 338   1999ef="D5c19the  is throold valu seq19the>1999atio---------------d="L318" cla5s="line" 5ame="L338"> 338   20h5ef="D5c20h5ef is throold valu seq20h5e>20h58" id=/pre> 338   20h1ef="D5c20hentation/memory-barrier20hen>20h82" iLife isn'toquitemas simplemas it7mL27appear abovt, howx28r:bfoxtwiele ttrd="L294" cla3s="line" 3ame="L294"> 294   20h2ef="D5c20h offirst load reall
20h2riercach sLae
 294   20h3ef="D5c20hentmrrierr
20h3tatiwee obr ontated.ulTtis #eansL ive 294   20h4ef="D5c20htioe me-numbeive.  cer 20hti>20h85" ievvntuallyLbecome visixt# xn ae o-bas,5t hre's neiguaranteemcive 294   20h5ef="D5c20hy elerr
erceivo"oey  su20hy >20h5Qtatbecome appar"lirin oma#s

q ontat on omose oiert -bas.d="L301" cla5s="line" 5ame="L301"> 301   20h6ef="D5c20hent="DoassueB mighs bth20hen>20h6rierd="L286" cla4s="line" 4ame="L351"> 351   20h7ef="D5c20hmeme me-numbeive.bankde20hme>20h18" id="L318" cla5s="line" 5ame="L338"> 338   20h8ef="D5c20htemodd-numbeive.bankdse20hte>20h8QtatConsmorytdealion wiie amsystem  ive 325   20h9ef="D5c20hhe  is throold valu seq20hhe>20h9atiohas 351   2015ef="D5c20AD *B,  X = < href="D20AD >20AD8" id="L318" cla5s="line" 5ame="L338"> 338   2011ef="D5c20AD *B,  STORP,  1ation/m20AD >20A1Qtation/memoooooooooooooid="L286" cla4s="line" 4ame="L351"> 351   2012ef="D5c20 = LOAD {*A,,,,,        20 = >20A2Qtation/memoooooooooooooioooooooooooooooooooooooooo+--------+d="L286" cla4s="line" 4ame="L351"> 351   20A3ef="D5c20*A = X; Y =             20*A >20A3Qtation/memoooooooooooooioooooo+---------+ooooooooo| would b|d="L286" cla4s="line" 4ame="L351"> 351   20A4ef="D5c20*A = Y = X;












20*A >20A4rier would b+--------+ld:d+--->|mCach  351   20A5ef="D5c20mentation/memory-barrier20men>20A5rier would b| would b| w:u| wou+---------+ooooooooo| would b|d="L286" cla4s="line" 4ame="L351"> 351   20A6ef="D5c20mentation/memory-barrier20men>20A6rier would b| w-ba 1<|<---+oooooooooooooooooooooooo| would b|d="L286" cla4s="line" 4ame="L351"> 351   20A7ef="D5c20mentThrfrriers should no20men>20A7rier would b| would b| w:u| wou+---------+ooooooooo| would b|d="L286" cla4s="line" 4ame="L351"> 351   20A8ef="D5c20ned rol rcu_ceivff tnce(20ned>20A8rier woul  b+--------+ld:d+--->|mCach  351   20A9ef="D5c20g send load is i RCU dep20g s>20A9Qtation/memoooooooooooooioooooo+---------+ooooooooo| would b|d="L286" cla4s="line" 4ame="L351"> 351   2025ef="D5c20mentenepreplaciarriond l20men>20meQtation/memoooooooooooooioooooooooooooooooooooooooo|mMe="L3u|d="L286" cla4s="line" 4ame="L351"> 351   20m1ef="D5c20mentation/memory-barrier20men>20m1Qtation/memoooooooooooooioooooo+---------+ooooooooo| System |d="L286" cla4s="line" 4ame="L351"> 351   20m2ef="D5c20mentrol alsoa="Doc infor20men>20m2rier would b+--------+ld:d+--->|mCach  351   2023ef="D5c20mentation/memory-barrier20men>20m3rier would b| would b| w:u| wou+---------+ooooooooo| would b|d="L286" cla4s="line" 4ame="L351"> 351   2024ef="D5c20mentation/memory-barrier20men>20m4rier would b| w-ba 2<|<---+oooooooooooooooooooooooo| would b|d="L286" cla4s="line" 4ame="L351"> 351   2025ef="D5c20y baCONTROL DEPENDENCIEn20y b>20m5rier would b| would b| w:u| wou+---------+ooooooooo| would b|d="L286" cla4s="line" 4ame="L351"> 351   2026ef="D5c20poneument-
 351   2027ef="D5c20mentation/memory-barrier20men>20m7Qtation/memoooooooooooooioooooo+---------+ooooooooo| would b|d="L286" cla4s="line" 4ame="L351"> 351   2028ef="D5c20ned Ay.  If the address 20ned>20m8Qtation/memoooooooooooooioooooooooooooooooooooooooo+--------+d="L286" cla4s="line" 4ame="L351"> 351   2029ef="D5c20g ses should normally  m20g s>20m9Qtation/memoooooooooooooid="L286" cla4s="line" 4ame="L351"> 351   2035ef="D5c20thataodetation/memory-ba20tha>20th8" id="L318" cla5s="line" 5ame="L338"> 338   2031ef="D5c20mentation/memory-barrier20men>20t1QtatImagmormoma#system has 351   2032ef="D5c20 = LOAD {*A,q,  &ata20 = >20t2atiod="L282" cla5s="line" 5ame="L322"> 322   20t3ef="D5c20*A = X; Y = if (p)ation/20*A >20t3rier (*)yag odd-numbryed cach uemorm#L27br in cach  A, cach  CuorLit7mL27stee Lbrd="L294" cla3s="line" 3ame="L294"> 294   2034ef="D5c20*A = Y = X;








q,  20*A >20t4rier woulresmorlirin me="L2;d="L335" cla5s="line" 5ame="L312"> 312   20t5ef="D5c20AD *B,  X = <rrier wo20AD >20t16" id="L216" cla5s="line" 5ame="L316"> 316   20t6ef="D5c20 = LOAD {*A,x  X*qtation20 = >20t6rier (*)yag evvn-numbryed cach uemorm#L27br in cach  B, cach  DuorLit7mL27stee Lbrd="L294" cla3s="line" 3ame="L294"> 294   2037ef="D5c20mentation/memory-barrier20men>20t7rier woulresmorlirin me="L2;d="L335" cla5s="line" 5ame="L312"> 312   20t8ef="D5c20ill r:
20t89" id="L289" cla4s="line" 4ame="L279"> 279int20t9ef="D5c20g ses should ncy is f="D20g s>20t9atioi(*)ywhilstltiv -ba cre
 is in.txrogation xna#cach ,toma#oiert cach  #L27brd="L289" cla4s="line" 4ame="L279"> 279int2045ef="D5c20 = Latas
pte compipcumic20 = >20 =rier woulmakion usebofaoma#bus #o accessu ivlrest ofaoma#system - 279int2041ef="D5c20 = Lct"Documesetation/me20 = >20 1tation/medisplacemaedirtybcach emormox 312   2042ef="D5c20mentation/memory-barrier20men>20 2atiod="L282" cla5s="line" 5ame="L322"> 322   2043ef="D5c20 = LOAD {*A,q,  &ata20 = >20 3rier (*)yeach cach  has 325   20 4ef="D5c20*A = X; Y = if (p)ation/20*A >20 4rier woultoL#Lintaol 312   2045ef="D5c20*A = X; Y =         q,  20*A >20 16" id="L216" cla5s="line" 5ame="L316"> 316   2046ef="D5c20AD *B,  X = <ld norma20AD >20 6rier (*)yth ucohere cy.queue is7not"flusa d 294   2047ef="D5c20 = LOAD {*A,x  X*qtation20 = >20 7rier woulpres"lirin oma#cach ,tevvnythough 325   20 8ef="D5c20mentation/memory-barrier20men>20 8rier woulpoteliiallyL senta 301   2049ef="D5c20mentation/memory-barrier20men>20 9atiod="L301" cla5s="line" 5ame="L301"> 301   2055ef="D5c20mentg&quBDocume PAIRINGa20men>20meQtatImagmor,5 ivn,mcive 301d="L301" cla5s="line" 5ame="L301"> 301   2051ef="D5c20mentment-
 301   20m2ef="D5c20mentation/memory-barrier20men>20m2Qtatthe requisersuontatid="L286" cla4s="line" 4ame="L351"> 351   2053ef="D5c20 = LWnrnDda _e cos;
20m94" id="L294" cla3s="line" 3ame="L294"> 294   20m4ef="D5c20; Y  305 (2) 5at5tru20; Y>20m4rier would b-ba 1<<<<<<<<<<<-ba 2<<<<<<<<<<<-OMMENTd="L294" cla3s="line" 3ame="L294"> 294   20m5ef="D5c20AD *A,  STORB,  4tation/20AD >20m5rier would biiiiiiiiiiiiiiibiiiiiiiiiiiiiiibiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiid="L252" cla5s="line" 5ame="L307"> 307   20m6ef="D5c20AD *B,  X = < href="D20AD >20m6Qtation/memoooooooooooooooooooooooooooooooooubii 0, vbii 1 andLpbii &u, qbii &ud="L252" cla5s="line" 5ame="L307"> 307   20m7ef="D5c20AD *B,  STORP,  &tat20AD >20m7Qtation/memovbi 2;d="L335" cla5s="line" 5ame="L312"> 312   2058ef="D5c20*A = X; Y =             20*A >20m8Qtation/memosmp_wmb();ooooooooooooooooooooooMak
 surelchangs ceiv is7visixt# bfore
d="L335" cla5s="line" 5ame="L312"> 312   2059ef="D5c20*A = Y = X;












20*A >20m9Qtation/memoooooooooooooooooooooooooooooooooochangs ceipd="L335" cla5s="line" 5ame="L312"> 312   2065ef="D5c20mentation/memory-barrier20men>20meQtation/memo<A:modify v=2>/memoooooooooooooov is7now in cach  A exclusivelyd="L282" cla3s="line" 3ame="L282"> 282VAR20m1ef="D5c20s spT per dependenclre a20s s>20m1Qtation/memopbi &v;d="L335" cla5s="line" 5ame="L312"> 312   2062ef="D5c20and  operati, Q,hat  any20and>20m2Qtation/memo<B:modify p=&v>/memooooooooooooop is7now in cach  B exclusivelyd="L282" cla3s="line" 3ame="L282"> 282VAR20m3ef="D5c20mentation/memory-barrier20men>20m94" id="L294" cla3s="line" 3ame="L294"> 294   2064ef="D5c20; Y = *A;
20m42" iTtr wiersu#e="L3u1"> 301tfoxcestoma#oiert -bas in oma#system ceiperceivey iatd="L289" cla4s="line" 4ame="L279"> 279int20m5ef="D5c20; Y = *A;
20m5Qtatthe ricnl#-ba's cach s 279int20m6ef="D5c20mentation/memory-barrier20men>20m6Qtatnow imagmormomve 351   2067ef="D5c20emorBut!,,as c2 depend l20emo>20m18" id="L318" cla5s="line" 5ame="L338"> 338   2068ef="D5c20e otlrede compitnces:
20m8rier would b-ba 1<<<<<<<<<<<-ba 2<<<<<<<<<<<-OMMENTd="L294" cla3s="line" 3ame="L294"> 294   2069ef="D5c20mentation/memory-barrier20men>20m9rier would biiiiiiiiiiiiiiibiiiiiiiiiiiiiiibiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiid="L252" cla5s="line" 5ame="L307"> 307   2075ef="D5c20; Y = *A;
20; rier would b...d="L301" cla5s="line" 5ame="L301"> 301   2071ef="D5c20mentation/memory-barrier20men>20;1Qtation/memoooooooooooooooooqbi p;d="L335" cla5s="line" 5ame="L312"> 312   2072ef="D5c20mentWhilsoblem fa hrbarn20men>20;2Qtation/memoooooooooooooooooxbi *q;d="L335" cla5s="line" 5ame="L312"> 312   2073ef="D5c20mentisn depet,Documenif 20men>20;94" id="L294" cla3s="line" 3ame="L294"> 294   2074ef="D5c20mentAlphantation/memory-20men>20;42" iTtr abovt pair of 294   20;5ef="D5c20mentation/memory-barrier20men>20;5riercach emormholdion p<#L27get updated i5ixna#ofaoma#second -ba's cach s 294   20;6ef="D5c20s spro da _epeothenify b20s s>20;6Qtatthe update #o oma#cach emormholdion v is7delayed i5itir oiert xfaoma#secondd="L294" cla3s="line" 3ame="L294"> 294   20;7ef="D5c20ion aetwdento then itŀion>20;7rier-ba's cach s 351   2078ef="D5c20mentation/memory-barrier20men>20;89" id="L289" cla4s="line" 4ame="L279"> 279int2079ef="D5c20 = LOAD {*A,as c1AD {*A,20 = >20;9rier would b-ba 1<<<<<<<<<<<-ba 2<<<<<<<<<<<-OMMENTd="L294" cla3s="line" 3ame="L294"> 294   2085ef="D5c20 = LOAD {*A, href="Docum20 = >20 =rier would biiiiiiiiiiiiiiibiiiiiiiiiiiiiiibiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiid="L252" cla5s="line" 5ame="L307"> 307   2081ef="D5c20; Y = *A;
20 1Qtation/memoooooooooooooooooooooooooooooooooubii 0, vbii 1 andLpbii &u, qbii &ud="L252" cla5s="line" 5ame="L307"> 307   2082ef="D5c20AD *A,  STORB,  4tation/20AD >20 2Qtation/memovbi 2;d="L335" cla5s="line" 5ame="L312"> 312   2083ef="D5c20AD *B,  X = < href="D20AD >20 3Qtation/memosmp_wmb();d="L335" cla5s="line" 5ame="L312"> 312   2084ef="D5c20AD *B,  STORP,  &tat20AD >20 4Qtation/memo<A:modify v=2>/m<C:busy>d="L335" cla5s="line" 5ame="L312"> 312   20 5ef="D5c20*A = X; Y =             20*A >20 5Qtation/memooooooooooooooooo<C:queue v=2>d="L335" cla5s="line" 5ame="L312"> 312   20 6ef="D5c20*A = X; Y =             20*A >20 6Qtation/memopbi &v;oooooooooqbi p;d="L335" cla5s="line" 5ame="L312"> 312   2087ef="D5c20*A = Y = X;












20*A >20 7Qtation/memooooooooooooooooo<D:request p>d="L335" cla5s="line" 5ame="L312"> 312   20 8ef="D5c20mentation/memory-barrier20men>20 8Qtation/memo<B:modify p=&v>/<D:commit p=&v>d="L335" cla5s="line" 5ame="L312"> 312   20 9ef="D5c20ill r:
20 9Qtation/memooooooooooooooooo<D:read 312   2095ef="D5c20mentenirdn"Documilito th20men>20meQtation/memoooooooooooooooooxbi *q;d="L335" cla5s="line" 5ame="L312"> 312   2091ef="D5c20mentation/memory-barrier20men>20m1Qtation/memooooooooooooooooo<C:read<*q>/memoReads 325   2092ef="D5c20s offirst load reall
20m2Qtation/memooooooooooooooooo<C:unbusy>d="L335" cla5s="line" 5ame="L312"> 312   2093ef="D5c20mentmrrierr
20m3Qtation/memooooooooooooooooo<C:commit v=2>d="L335" cla5s="line" 5ame="L312"> 312   2094ef="D5c20atioe me-numbeive.  cer 20ati>20m85" id="L285" cla5s="line" 5ame="L325"> 325   20m5ef="D5c20ny elerr
erceivo"oey  su20ny >20m5QtatBasically,ywhilstlboieicach emors wee obr updated on<-ba 2 325   20m6ef="D5c20ment="DoassueB mighs bth20men>20m6Qtatnoiguaranteemcive,twiieout in.txvvnti 5,5 iv ontat of update wee obr oma#s

qd="L285" cla5s="line" 5ame="L325"> 325   20m7ef="D5c20 meme me-numbeive.bankde20 me>20m7Qtatasmtive 301   2098ef="D5c20stemodd-numbeive.bankdse20ste>20m89" id="L289" cla4s="line" 4ame="L279"> 279int2099ef="D5c20the  is throold valu seq20the>20m9atiod="L301" cla5s="line" 5ame="L301"> 301   21h5ef="D5c21h5ef is throold valu seq21h5e>21h58" iTo in.txvvne,twe 301toxta 301   21h1ef="D5c21hentation/memory-barrier21hen>21h82" i1"> 301tbetweng oma#riads.ulTtis wee ofoxcemoma#cach uceicommit its cohere cyd="L294" cla3s="line" 3ame="L294"> 294   21h2ef="D5c21h offirst load reall
21h2rierqueue bfore
 351   21h3ef="D5c21hentmrrierr
21094" id="L294" cla3s="line" 3ame="L294"> 294   21h4ef="D5c21htioe me-numbeive.  cer 21hti>2104rier would b-ba 1<<<<<<<<<<<-ba 2<<<<<<<<<<<-OMMENTd="L294" cla3s="line" 3ame="L294"> 294   21h5ef="D5c21hy elerr
erceivo"oey  su21hy >2105rier would biiiiiiiiiiiiiiibiiiiiiiiiiiiiiibiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiid="L252" cla5s="line" 5ame="L307"> 307   21h6ef="D5c21hent="DoassueB mighs bth21hen>2106Qtation/memoooooooooooooooooooooooooooooooooubii 0, vbii 1 andLpbii &u, qbii &ud="L252" cla5s="line" 5ame="L307"> 307   21h7ef="D5c21hmeme me-numbeive.bankde21hme>2107Qtation/memovbi 2;d="L335" cla5s="line" 5ame="L312"> 312   21h8ef="D5c21htemodd-numbeive.bankdse21hte>2108Qtation/memosmp_wmb();d="L335" cla5s="line" 5ame="L312"> 312   21h9ef="D5c21hhe  is throold valu seq21hhe>2109Qtation/memo<A:modify v=2>/m<C:busy>d="L335" cla5s="line" 5ame="L312"> 312   2115ef="D5c21AD *B,  X = < href="D21AD >211eQtation/memooooooooooooooooo<C:queue v=2>d="L335" cla5s="line" 5ame="L312"> 312   2111ef="D5c21AD *B,  STORP,  1ation/m21AD >2111Qtation/memopbi &v;oooooooooqbi p;d="L335" cla5s="line" 5ame="L312"> 312   2112ef="D5c21 = LOAD {*A,,,,,        21 = >21A2Qtation/memooooooooooooooooo<D:request p>d="L335" cla5s="line" 5ame="L312"> 312   21A3ef="D5c21*A = X; Y =             21*A >21A3Qtation/memo<B:modify p=&v>/<D:commit p=&v>d="L335" cla5s="line" 5ame="L312"> 312   21A4ef="D5c21*A = Y = X;












21*A >21A4rier would boooooooooooooooo<D:read 312   21A5ef="D5c21mentation/memory-barrier21men>2115Qtation/memooooooooooooooooosmp_read_2"> 312_depends()d="L301" cla5s="line" 5ame="L301"> 301   2116ef="D5c21mentation/memory-barrier21men>2116Qtation/memooooooooooooooooo<C:unbusy>d="L335" cla5s="line" 5ame="L312"> 312   21A7ef="D5c21mentThrfrriers should no21men>2117Qtation/memooooooooooooooooo<C:commit v=2>d="L335" cla5s="line" 5ame="L312"> 312   21A8ef="D5c21ned rol rcu_ceivff tnce(21ned>2118Qtation/memoooooooooooooooooxbi *q;d="L335" cla5s="line" 5ame="L312"> 312   21A9ef="D5c21g send load is i RCU dep21g s>21A9Qtation/memooooooooooooooooo<C:read<*q>/memoReads 325   2125ef="D5c21mentenepreplaciarriond l21men>212h8" id="L318" cla5s="line" 5ame="L338"> 338   21m1ef="D5c21mentation/memory-barrier21men>21282" id="L282" cla3s="line" 3ame="L282"> 282VAR2122ef="D5c21mentrol alsoa="Doc infor21men>21m2rierTtis sort ofaproblem canobr e coun.txed on 282VAR2123ef="D5c21mentation/memory-barrier21men>21m3riersplit#cach ucive 301   2124ef="D5c21mentation/memory-barrier21men>21m4rierWhilstlmostl-bas do 301ton  ivlread 338   21m5ef="D5c21y baCONTROL DEPENDENCIEn21y b>21m5rieraccessudepends xn alread,7not"ae odo,LsoLit7mL27not"bvlrelied 301   2126ef="D5c21poneument-
 351   2127ef="D5c21mentation/memory-barrier21men>21m7QtatOiert -bas mL27alsoohave split#cach s, butLmust coordintiombetweng oma#variousd="L285" cla5s="line" 5ame="L325"> 325   2128ef="D5c21ned Ay.  If the address 21ned>21m8Qtatcach eets foxtnoxmal #e="L3uaccessss.ulTtr semantics ofaoma#Alpha 294   2129ef="D5c21g ses should normally  m21g s>21m9Qtatne dofoxtcoordintii 5min oma#absencebofa#e="L3u1"> 301s.d="L301" cla5s="line" 5ame="L301"> 301   2135ef="D5c21thataodetation/memory-ba21tha>21th8" id="L318" cla5s="line" 5ame="L338"> 338   2131ef="D5c21mentation/memory-barrier21men>21382" id="L282" cla3s="line" 3ame="L282"> 282VAR2132ef="D5c21 = LOAD {*A,q,  &ata21 = >21t2atioCACHE COHERENCY VS DMAd="L282" cla3s="line" 3ame="L282"> 282VAR2133ef="D5c21*A = X; Y = if (p)ation/21*A >21t3rier----------------------d="L282" cla3s="line" 3ame="L282"> 282VAR2134ef="D5c21*A = Y = X;








q,  21*A >21385" id="L285" cla5s="line" 5ame="L325"> 325   21t5ef="D5c21AD *B,  X = <rrier wo21AD >21t16" iNot"ae osystemsL#Lintaol 301   21t6ef="D5c21 = LOAD {*A,x  X*qtation21 = >21t6riersusatcases,5a devicemat.tmption DMA mL27obtaol 301   21t7ef="D5c21mentation/memory-barrier21men>21t7rierdirtybcach irioss<#L27br resmorlirin oma#cach sLofavariouso-bas,5and mL27notd="L301" cla5s="line" 5ame="L301"> 301   21t8ef="D5c21ill r:
21t89" ihave beng wierten 301   21t9ef="D5c21g ses should ncy is f="D21g s>21t9atio iv kerldlLmust flusa5 iv overlappion biis ofacach ionyeach -ba (and mL2brd="L289" cla4s="line" 4ame="L279"> 279int2145ef="D5c21 = Latas
pte compipcumic21 = >214e8" iinvalidate ttrmtas 301   2141ef="D5c21 = Lct"Documesetation/me21 = >21482" id="L282" cla3s="line" 3ame="L282"> 282VAR2142ef="D5c21mentation/memory-barrier21men>21 2atioIn addia" 5,aoma#demo DMA'd 282VAR2143ef="D5c21 = LOAD {*A,q,  &ata21 = >21 3riercach irioss 325   21 4ef="D5c21*A = X; Y = if (p)ation/21*A >21 4rierinsiall0dLits own demo, orycach irioss 325   21 5ef="D5c21*A = X; Y =         q,  21*A >21 16" iobscuremoma#face 325   21 6ef="D5c21AD *B,  X = <ld norma21AD >21 6rieris7discaedddufrom oma#-ba's cach  and reloaded.ulTotdeal.wiie  iis,7 ivd="L285" cla5s="line" 5ame="L325"> 325   21 7ef="D5c21 = LOAD {*A,x  X*qtation21 = >21 7rierappropriate part of  iv kerldlLmust invalidate ttr overlappion biis ofa ivd="L285" cla5s="line" 5ame="L325"> 325   21 8ef="D5c21mentation/memory-barrier21men>2148Qtatcach ionyeach -ba.d="L301" cla5s="line" 5ame="L301"> 301   2149ef="D5c21mentation/memory-barrier21men>21 9atiod="L301" cla5s="line" 5ame="L301"> 301   2155ef="D5c21mentg&quBDocume PAIRINGa21men>21meQtatSee la5s="line" 5acach tlb/a> ofoxtmre
 infoxmaii 5mon cach  mLnage="li.d="L301" cla5s="line" 5ame="L301"> 301   2151ef="D5c21mentment-
 282VAR21m2ef="D5c21mentation/memory-barrier21men>2152atiod="L282" cla5s="line" 5ame="L322"> 322   2153ef="D5c21 = LWnrnDda _e cos;
21m94" iCACHE COHERENCY VS MMIOd="L282" cla5s="line" 5ame="L322"> 322   2154ef="D5c21; Y  305 (2) 5at5tru21; Y>21m4rier-----------------------d="L282" cla3s="line" 3ame="L282"> 282VAR21m5ef="D5c21AD *A,  STORB,  4tation/21AD >21516" id="L216" cla5s="line" 5ame="L316"> 316   21m6ef="D5c21AD *B,  X = < href="D21AD >21m6QtatMe="L3um pped I/O usuallyLtakns7placemtirough<#e="L3uricne" 5s  ive 301   21m7ef="D5c21AD *B,  STORP,  &tat21AD >21m7Qtatauwindow in oma#-ba's #e="L3uspacemtive 301   2158ef="D5c21*A = X; Y =             21*A >21m8Qtatthe usual 301   2159ef="D5c21*A = Y = X;












21*A >2159atiod="L301" cla5s="line" 5ame="L301"> 301   2165ef="D5c21mentation/memory-barrier21men>21meQtatAmongstltivsa#properties is7usuallyLtma#face 301   2161ef="D5c21s spT per dependenclre a21s s>21m1Qtatcachion vntirely and goLdirntalyLto 301   2162ef="D5c21and  operati, Q,hat  any21and>21m2QtatmL2, in esenta, overtakn accessss<#o cach dome="L3u ive 301   21m3ef="D5c21mentation/memory-barrier21men>21m94" iAu#e="L3u1"> 301tisn'tosuffici"lirin susatatcase, butLraiert oma#cach umust brd="L289" cla4s="line" 4ame="L279"> 279int2164ef="D5c21; Y = *A;
21m42" iflusa d 279int2165ef="D5c21; Y = *A;
21m5Qtatany waybdepende i.d="L301" cla5s="line" 5ame="L301"> 301   21m6ef="D5c21mentation/memory-barrier21men>2166rierd="L286" cla4s="line" 4ame="L351"> 351   2167ef="D5c21emorBut!,,as c2 depend l21emo>21m18" id="L318" cla5s="line" 5ame="L338"> 338   2168ef="D5c21e otlrede compitnces:
21m8rieriiiiiiiiiiiiiiiiiiiiiiiiid="L252" cla5s="line" 5ame="L307"> 307   2169ef="D5c21mentation/memory-barrier21men>21m9rierTHE THINGS#-baS GET UP TOd="L282" cla5s="line" 5ame="L322"> 322   2175ef="D5c21; Y = *A;
21; rieriiiiiiiiiiiiiiiiiiiiiiiiid="L252" cla5s="line" 5ame="L307"> 307   2171ef="D5c21mentation/memory-barrier21men>21782" id="L282" cla3s="line" 3ame="L282"> 282VAR2172ef="D5c21mentWhilsoblem fa hrbarn21men>2172QtatAiprogrammrt mightLtakn i bfoxtgrantedmomve 338   2173ef="D5c21mentisn depet,Documenif 21men>21;94" ioperne" 5s in exatalyLtiv ontat spntifidd,LsoLcive 294   21;4ef="D5c21mentAlphantation/memory-21men>21;42" igivng ttr followion piecebofacod uceiexecuieid="L286" cla4s="line" 4ame="L351"> 351   21;5ef="D5c21mentation/memory-barrier21men>21716" id="L216" cla5s="line" 5ame="L316"> 316   21;6ef="D5c21s spro da _epeothenify b21s s>2176Qtation/memoabi *A;d="L335" cla5s="line" 5ame="L312"> 312   21;7ef="D5c21ion aetwdento then itŁion>2177Qtation/memo*Bbi b;d="L335" cla5s="line" 5ame="L312"> 312   21;8ef="D5c21mentation/memory-barrier21men>2178Qtation/memocbi *C;d="L335" cla5s="line" 5ame="L312"> 312   21;9ef="D5c21 = LOAD {*A,as c1AD {*A,21 = >21;9rier would bdbi *D;d="L335" cla5s="line" 5ame="L312"> 312   2185ef="D5c21 = LOAD {*A, href="Docum21 = >21 =rier would b*Ebi e;d="L335" cla5s="line" 5ame="L312"> 312   2181ef="D5c21; Y = *A;
21882" id="L282" cla3s="line" 3ame="L282"> 282VAR2182ef="D5c21AD *A,  STORB,  4tation/21AD >2182Qtatthey would7 ivn expntamomve 325   2183ef="D5c21AD *B,  X = < href="D21AD >21 3Qtatinsiruta" 5 bfore
 325   2184ef="D5c21AD *B,  STORP,  &tat21AD >21 4Qtatoperne" 5s as seen 351   21 5ef="D5c21*A = X; Y =             21*A >21816" id="L216" cla5s="line" 5ame="L316"> 316   21 6ef="D5c21*A = X; Y =             21*A >21 6Qtation/memoLOAD *A, STOREo*B,oLOAD *C,oLOAD *D, STOREo*E.d="L301" cla5s="line" 5ame="L301"> 301   2187ef="D5c21*A = Y = X;












21*A >21818" id="L318" cla5s="line" 5ame="L338"> 338   21 8ef="D5c21mentation/memory-barrier21men>21889" id="L289" cla4s="line" 4ame="L279"> 279int21 9ef="D5c21ill r:
21 9QtatReality is,7ofacourse, musatmessiat.  Wiie many -bas and compil79<,7 iv abovtd="L289" cla4s="line" 4ame="L279"> 279int2195ef="D5c21mentenirdn"Documilito th21men>21meQtatirdumptixnLdoesn'toholdLbecauseid="L286" cla4s="line" 4ame="L351"> 351   2191ef="D5c21mentation/memory-barrier21men>21982" id="L282" cla3s="line" 3ame="L282"> 282VAR2192ef="D5c21s offirst load reall
21m2Qtati(*)yriads ae
 282VAR2193ef="D5c21mentmrrierr
21m3Qtation/mexecuiion progress,ywhee
as stre
s canooften 282VAR2194ef="D5c21atioe me-numbeive.  cer 21ati>2194rier woulproblem;d="L335" cla5s="line" 5ame="L312"> 312   21m5ef="D5c21ny elerr
erceivo"oey  su21ny >21916" id="L216" cla5s="line" 5ame="L316"> 316   21m6ef="D5c21ment="DoassueB mighs bth21men>2196Qtati(*)yriads #L27br donemspeculttively,5and oma#e
sult7discaedddushould7it#provtd="L289" cla4s="line" 4ame="L279"> 279int2197ef="D5c21 meme me-numbeive.bankde21 me>2197Qtation/mto7have beng unnecessaL2;d="L335" cla5s="line" 5ame="L312"> 312   2198ef="D5c21stemodd-numbeive.bankdse21ste>21m89" id="L289" cla4s="line" 4ame="L279"> 279int2199ef="D5c21the  is throold valu seq21the>2199Qtati(*)yriads #L27br donemspeculttively,5leadion #o oma#e
sult7havion bevn fetch dd="L289" cla4s="line" 4ame="L279"> 279int22h5ef="D5c22h5ef is throold valu seq22h5e>220=rier woulve 312   22h1ef="D5c22hentation/memory-barrier22hen>22082" id="L282" cla3s="line" 3ame="L282"> 282VAR22h2ef="D5c22h offirst load reall
2202Qtati(*)y iv ontat of oma#me="L3uaccessss<#L27bvlrearrangsdoceipromoiombet.tx 282VAR22h3ef="D5c22hentmrrierr
2203Qtation/mof 312   22h4ef="D5c22htioe me-numbeive.  cer 22hti>22085" id="L285" cla5s="line" 5ame="L325"> 325   22h5ef="D5c22hy elerr
erceivo"oey  su22hy >2205rier (*)yriads agdLstre
s #L27bvlcombin doceiimprovr perfoxmancebwivn talkion #od="L285" cla5s="line" 5ame="L325"> 325   22h6ef="D5c22hent="DoassueB mighs bth22hen>2206Qtation/mme="L3uor I/O haedwareit ve 294   22h7ef="D5c22hmeme me-numbeive.bankde22hme>2207Qtation/mthus cuttion down xnLtransata" 5 setuplcosts (me="L3uagdLPCIidevices #L2d="L285" cla5s="line" 5ame="L325"> 325   22h8ef="D5c22htemodd-numbeive.bankdse22hte>2208Qtation/mboieibe axt# teido  iis);5andd="L301" cla5s="line" 5ame="L301"> 301   2209ef="D5c22hhe  is throold valu seq22hhe>2209atiod="L301" cla5s="line" 5ame="L301"> 301   2215ef="D5c22AD *B,  X = < href="D22AD >221eQtati(*)y iv -ba's demo cach  mL27asenta 294   2211ef="D5c22AD *B,  STORP,  1ation/m22AD >2211Qtation/mmechanisms mL27alleviate ttis - once oma#stre
 has 294   2212ef="D5c22 = LOAD {*A,,,,,        22 = >22A2Qtation/m-5t hre's neiguaranteemcive 294   2213ef="D5c22*A = X; Y =             22*A >22A3Qtation/montat teioiert -bas.d="L301" cla5s="line" 5ame="L301"> 301   22A4ef="D5c22*A = Y = X;












22*A >22185" id="L285" cla5s="line" 5ame="L325"> 325   22A5ef="D5c22mentation/memory-barrier22men>2215QtatSo whve 325   22A6ef="D5c22mentation/memory-barrier22men>2216rierisid="L286" cla4s="line" 4ame="L351"> 351   22A7ef="D5c22mentThrfrriers should no22men>22118" id="L318" cla5s="line" 5ame="L338"> 338   22A8ef="D5c22ned rol rcu_ceivff tnce(22ned>2218Qtation/memoLOAD *A, ...,oLOAD {*C,*D}, STOREo*E, STOREo*Bd="L318" cla5s="line" 5ame="L338"> 338   22A9ef="D5c22g send load is i RCU dep22g s>2219atiod="L301" cla5s="line" 5ame="L301"> 301   2225ef="D5c22mentenepreplaciarriond l22men>22meQtation/memo(Where "LOAD {*C,*D}" is7alcombin doriad)d="L301" cla5s="line" 5ame="L301"> 301   22m1ef="D5c22mentation/memory-barrier22men>22282" id="L282" cla3s="line" 3ame="L282"> 282VAR2222ef="D5c22mentrol alsoa="Doc infor22men>2222atiod="L282" cla5s="line" 5ame="L322"> 322   2223ef="D5c22mentation/memory-barrier22men>22m3rierHowx28r,7it#is7guaranteedmomve 301   2224ef="D5c22mentation/memory-barrier22men>22m4rier_own_uaccessss 338   22m5ef="D5c22y baCONTROL DEPENDENCIEn22y b>22m5rier8"> 338.  ForLinsiancebwiie  ivlfollowion cod id="L286" cla4s="line" 4ame="L351"> 351   2226ef="D5c22poneument-
 351   2227ef="D5c22mentation/memory-barrier22men>22m7Qtation/memoUbi *A;d="L335" cla5s="line" 5ame="L312"> 312   2228ef="D5c22ned Ay.  If the address 22ned>22m8Qtation/memo*Abi V;d="L335" cla5s="line" 5ame="L312"> 312   2229ef="D5c22g ses should normally  m22g s>22m9Qtation/memo*Abi W;d="L335" cla5s="line" 5ame="L312"> 312   2235ef="D5c22thataodetation/memory-ba22tha>223eQtation/memoXbi *A;d="L335" cla5s="line" 5ame="L312"> 312   2231ef="D5c22mentation/memory-barrier22men>2231Qtation/memo*Abi Y;d="L335" cla5s="line" 5ame="L312"> 312   2232ef="D5c22 = LOAD {*A,q,  &ata22 = >2232Qtation/memoZbi *A;d="L335" cla5s="line" 5ame="L312"> 312   2233ef="D5c22*A = X; Y = if (p)ation/22*A >22394" id="L294" cla3s="line" 3ame="L294"> 294   2234ef="D5c22*A = Y = X;








q,  22*A >22385" iand irdumion no in.txvvnti 5Lby5aneexternal 294   2235ef="D5c22AD *B,  X = <rrier wo22AD >2235Qtatthe final 351   22t6ef="D5c22 = LOAD {*A,x  X*qtation22 = >2236rierd="L286" cla4s="line" 4ame="L351"> 351   22t7ef="D5c22mentation/memory-barrier22men>2237Qtation/memoUbi= 282VAR22t8ef="D5c22ill r:
2238Qtation/memoXbii Wd="L282" cla3s="line" 3ame="L282"> 282VAR22t9ef="D5c22g ses should ncy is f="D22g s>2239Qtation/memoZbii Yd="L282" cla3s="line" 3ame="L282"> 282VAR2245ef="D5c22 = Latas
pte compipcumic22 = >2240Qtation/memo*Abii Yd="L282" cla3s="line" 3ame="L282"> 282VAR2241ef="D5c22 = Lct"Documesetation/me22 = >22482" id="L282" cla3s="line" 3ame="L282"> 282VAR2242ef="D5c22mentation/memory-barrier22men>2242rierTteacod uabovt mL27cause 338   2243ef="D5c22 = LOAD {*A,q,  &ata22 = >22 3rieraccessssid="L286" cla4s="line" 4ame="L351"> 351   22 4ef="D5c22*A = X; Y = if (p)ation/22*A >22485" id="L285" cla5s="line" 5ame="L325"> 325   22 5ef="D5c22*A = X; Y =         q,  22*A >2245Qtation/memoU=LOAD *A, STOREo*A=V, STOREo*A=W, X=LOAD *A, STOREo*A=Y, Z=LOAD *Ad="L285" cla5s="line" 5ame="L325"> 325   22 6ef="D5c22AD *B,  X = <ld norma22AD >2246rierd="L286" cla4s="line" 4ame="L351"> 351   22 7ef="D5c22 = LOAD {*A,x  X*qtation22 = >22 7rieri5itiat 338   2248ef="D5c22mentation/memory-barrier22men>2248Qtatcombinaii 5mof ele="lislcombin doorLdiscaeddd,#provided oma#program's viewbofd="L285" cla5s="line" 5ame="L325"> 325   2249ef="D5c22mentation/memory-barrier22men>2249atio iv world re#Linslconsisteli.d="L301" cla5s="line" 5ame="L301"> 301   2255ef="D5c22mentg&quBDocume PAIRINGa22men>225h8" id="L318" cla5s="line" 5ame="L338"> 338   2251ef="D5c22mentment-
 312   22m2ef="D5c22mentation/memory-barrier22men>22m2Qtatthe -ba evvnysennuomam.d="L301" cla5s="line" 5ame="L301"> 301   2253ef="D5c22 = LWnrnDda _e cos;
22m94" id="L294" cla3s="line" 3ame="L294"> 294   2254ef="D5c22; Y  305 (2) 5at5tru22; Y>22m4rierForLinsianceid="L286" cla4s="line" 4ame="L351"> 351   22m5ef="D5c22AD *A,  STORB,  4tation/22AD >22516" id="L216" cla5s="line" 5ame="L316"> 316   22m6ef="D5c22AD *B,  X = < href="D22AD >22m6Qtation/memo*Abi V;d="L335" cla5s="line" 5ame="L312"> 312   22m7ef="D5c22AD *B,  STORP,  &tat22AD >22m7Qtation/memo*Abi W;d="L335" cla5s="line" 5ame="L312"> 312   2258ef="D5c22*A = X; Y =             22*A >22589" id="L289" cla4s="line" 4ame="L279"> 279int2259ef="D5c22*A = Y = X;












22*A >2259atio#L27bvlreduc doceid="L286" cla4s="line" 4ame="L351"> 351   2265ef="D5c22mentation/memory-barrier22men>226h8" id="L318" cla5s="line" 5ame="L338"> 338   2261ef="D5c22s spT per dependenclre a22s s>2261Qtation/memo*Abi W;d="L335" cla5s="line" 5ame="L312"> 312   2262ef="D5c22and  operati, Q,hat  any22and>2262atiod="L282" cla5s="line" 5ame="L322"> 322   22m3ef="D5c22mentation/memory-barrier22men>22m94" isince,7wiieout amriersu1"> 301,7it#canobr irdumedmomveitir esenta 325   2264ef="D5c22; Y = *A;
22m42" istreagebof 351   2265ef="D5c22; Y = *A;
22616" id="L216" cla5s="line" 5ame="L316"> 316   22m6ef="D5c22mentation/memory-barrier22men>2266Qtation/memo*Abi Y;d="L335" cla5s="line" 5ame="L312"> 312   2267ef="D5c22emorBut!,,as c2 depend l22emo>2267Qtation/memoZbi *A;d="L335" cla5s="line" 5ame="L312"> 312   2268ef="D5c22e otlrede compitnces:
22689" id="L289" cla4s="line" 4ame="L279"> 279int2269ef="D5c22mentation/memory-barrier22men>2269atio#L2,7wiieout am#e="L3u1"> 301,7bvlreduc doceid="L286" cla4s="line" 4ame="L351"> 351   2275ef="D5c22; Y = *A;
227h8" id="L318" cla5s="line" 5ame="L338"> 338   2271ef="D5c22mentation/memory-barrier22men>2271Qtation/memo*Abi Y;d="L335" cla5s="line" 5ame="L312"> 312   2272ef="D5c22mentWhilsoblem fa hrbarn22men>2272Qtation/memoZbi Y;d="L335" cla5s="line" 5ame="L312"> 312   2273ef="D5c22mentisn depet,Documenif 22men>22;94" id="L294" cla3s="line" 3ame="L294"> 294   22;4ef="D5c22mentAlphantation/memory-22men>22785" iand tir LOAD operne" 57nx28r7appear outsmormof 301   22;5ef="D5c22mentation/memory-barrier22men>22716" id="L216" cla5s="line" 5ame="L316"> 316   22;6ef="D5c22s spro da _epeothenify b22s s>2276rierd="L286" cla4s="line" 4ame="L351"> 351   22;7ef="D5c22ion aetwdento then itłion>2277QtatAND THEN THERE'S THE ALPHAd="L285" cla5s="line" 5ame="L325"> 325   22;8ef="D5c22mentation/memory-barrier22men>2278Qtat--------------------------d="L282" cla3s="line" 3ame="L282"> 282VAR22;9ef="D5c22 = LOAD {*A,as c1AD {*A,22 = >2279atiod="L301" cla5s="line" 5ame="L301"> 301   2285ef="D5c22 = LOAD {*A, href="Docum22 = >22 =rierTteaDEC Alpha<-ba isixna#ofaoma#mostlrelaxed -bas t hre is.  Not"onl3u ive,d="L294" cla3s="line" 3ame="L294"> 294   2281ef="D5c22; Y = *A;
22882" isome v01<" 5s ofaoma#Alpha<-ba have a split#demo cach , 294   2282ef="D5c22AD *A,  STORB,  4tation/22AD >2282Qtattwo semantically-related cach irioss 294   2283ef="D5c22AD *B,  X = < href="D22AD >22 3Qtatoma#demo depende cy.1"> 301treallyLbecomss 325   2284ef="D5c22AD *B,  STORP,  &tat22AD >22 4Qtatcach s 325   2285ef="D5c22*A = X; Y =             22*A >22816" ichangss vs 325   2286ef="D5c22*A = X; Y =             22*A >2286rierd="L286" cla4s="line" 4ame="L351"> 351   2287ef="D5c22*A = Y = X;












22*A >22818" iTma#Alpha 301tmodel.d="L285" cla5s="line" 5ame="L325"> 325   2288ef="D5c22mentation/memory-barrier22men>22889" id="L289" cla4s="line" 4ame="L279"> 279int22 9ef="D5c22ill r:
22 9QtatSee oma#subseta" 5  5 "Cach iCohere cy" abovt.d="L285" cla5s="line" 5ame="L325"> 325   2295ef="D5c22mentenirdn"Documilito th22men>229h8" id="L318" cla5s="line" 5ame="L338"> 338   2291ef="D5c22mentation/memory-barrier22men>22982" id="L282" cla3s="line" 3ame="L282"> 282VAR2292ef="D5c22s offirst load reall
22m2Qtatiiiiiiiiiiiid="L252" cla5s="line" 5ame="L307"> 307   2293ef="D5c22mentmrrierr
22m3QtatEXAMPLE USESd="L252" cla5s="line" 5ame="L307"> 307   2294ef="D5c22atioe me-numbeive.  cer 22ati>2294rieriiiiiiiiiiiid="L252" cla5s="line" 5ame="L307"> 307   2295ef="D5c22ny elerr
erceivo"oey  su22ny >22916" id="L216" cla5s="line" 5ame="L316"> 316   22m6ef="D5c22ment="DoassueB mighs bth22men>2296QtatCIRCULAR BUFFERSd="L252" cla5s="line" 5ame="L307"> 307   2297ef="D5c22 meme me-numbeive.bankde22 me>2297Qtat----------------d="L282" cla3s="line" 3ame="L282"> 282VAR2298ef="D5c22stemodd-numbeive.bankdse22ste>22m89" id="L289" cla4s="line" 4ame="L279"> 279int2299ef="D5c22the  is throold valu seq22the>2299QtatMe="L3u1"> 301s#canobr us doceiimple="li circultr bufferion wiieout oma#ne dd="L289" cla4s="line" 4ame="L279"> 279int23h5ef="D5c23h5ef is throold valu seq23h5e>230=rierofaarrick 351   23h1ef="D5c23hentation/memory-barrier23hen>23082" id="L282" cla3s="line" 3ame="L282"> 282VAR23h2ef="D5c23h offirst load reall
2302Qtation/memola3s="line" 3acircultr-bufferVd="L282" cla3s="line" 3ame="L282"> 282VAR23h3ef="D5c23hentmrrierr
23094" id="L294" cla3s="line" 3ame="L294"> 294   23h4ef="D5c23htioe me-numbeive.  cer 23hti>23085" iforLdetails.d="L301" cla5s="line" 5ame="L301"> 301   23h5ef="D5c23hy elerr
erceivo"oey  su23hy >23016" id="L216" cla5s="line" 5ame="L316"> 316   23h6ef="D5c23hent="DoassueB mighs bth23hen>2306rierd="L286" cla4s="line" 4ame="L351"> 351   23h7ef="D5c23hmeme me-numbeive.bankde23hme>2307Qtatiiiiiiiiiid="L252" cla5s="line" 5ame="L307"> 307   23h8ef="D5c23htemodd-numbeive.bankdse23hte>2308QtatREFERENCESd="L252" cla5s="line" 5ame="L307"> 307   2309ef="D5c23hhe  is throold valu seq23hhe>2309atioiiiiiiiiiid="L252" cla5s="line" 5ame="L307"> 307   2315ef="D5c23AD *B,  X = < href="D23AD >231h8" id="L318" cla5s="line" 5ame="L338"> 338   2311ef="D5c23AD *B,  STORP,  1ation/m23AD >2311QtatAlpha 294   2312ef="D5c23 = LOAD {*A,,,,,        23 = >23A2QtatDigital Press)d="L301" cla5s="line" 5ame="L301"> 301   2313ef="D5c23*A = X; Y =             23*A >23A3Qtation/memoChap.tx<5.2: Physical Address SpacemCharac.txisticsd="L301" cla5s="line" 5ame="L301"> 301   2314ef="D5c23*A = Y = X;












23*A >23A4rier would bChap.tx<5.4: Cach s 301   2315ef="D5c23mentation/memory-barrier23men>2315Qtation/memoChap.tx<5.5: Demo Shariond="L301" cla5s="line" 5ame="L301"> 301   2316ef="D5c23mentation/memory-barrier23men>2316Qtation/memoChap.tx<5.6:oRead/WiersuOntationd="L301" cla5s="line" 5ame="L301"> 301   2317ef="D5c23mentThrfrriers should no23men>23118" id="L318" cla5s="line" 5ame="L338"> 338   23A8ef="D5c23ned rol rcu_ceivff tnce(23ned>2318QtatAMD64 ArchitetauremProgrammrt's Manual Vols=" 2: SystemmProgrammiond="L301" cla5s="line" 5ame="L301"> 301   2319ef="D5c23g send load is i RCU dep23g s>23A9Qtation/memoChap.tx<7.1: Me="L3-AccesseOntationd="L301" cla5s="line" 5ame="L301"> 301   2325ef="D5c23mentenepreplaciarriond l23men>23meQtation/memoChap.tx<7.4: Bufferion and Combinion Me="L3uWiers 301   23m1ef="D5c23mentation/memory-barrier23men>23282" id="L282" cla3s="line" 3ame="L282"> 282VAR2322ef="D5c23mentrol alsoa="Doc infor23men>2322atioIA-32 Intel ArchitetauremSoftwareiDeveloper's Manual, Vols=" 3id="L286" cla4s="line" 4ame="L351"> 351   2323ef="D5c23mentation/memory-barrier23men>23m3rierSystemmProgrammion Guid d="L285" cla5s="line" 5ame="L325"> 325   2324ef="D5c23mentation/memory-barrier23men>2324rier would bChap.tx<7.1: Lick doAtomic Operne" 5sd="L285" cla5s="line" 5ame="L325"> 325   2325ef="D5c23y baCONTROL DEPENDENCIEn23y b>2325Qtation/memoChap.tx<7.2: Me="L3uOntationd="L301" cla5s="line" 5ame="L301"> 301   2326ef="D5c23poneument-
 325   2327ef="D5c23mentation/memory-barrier23men>23218" id="L318" cla5s="line" 5ame="L338"> 338   2328ef="D5c23ned Ay.  If the address 23ned>23m8QtatTma#SPARC ArchitetauremManual, V01<" 5 9d="L318" cla5s="line" 5ame="L338"> 338   2329ef="D5c23g ses should normally  m23g s>2329Qtation/memoChap.tx<8: Me="L3uModelsd="L285" cla5s="line" 5ame="L325"> 325   2335ef="D5c23thataodetation/memory-ba23tha>233eQtation/memoAppendix D: Formal Spntificaii 5mof oma#Me="L3uModelsd="L285" cla5s="line" 5ame="L325"> 325   2331ef="D5c23mentation/memory-barrier23men>2331Qtation/memoAppendix J:mProgrammion wiie  ivlMe="L3uModelsd="L285" cla5s="line" 5ame="L325"> 325   2332ef="D5c23 = LOAD {*A,q,  &ata23 = >2332atiod="L282" cla5s="line" 5ame="L322"> 322   2333ef="D5c23*A = X; Y = if (p)ation/23*A >23394" iUltraSPARC ProgrammrtmRefere ca#Manuald="L282" cla5s="line" 5ame="L322"> 322   2334ef="D5c23*A = Y = X;








q,  23*A >2334rier would bChap.tx<5: Me="L3uAccessss 322   2335ef="D5c23AD *B,  X = <rrier wo23AD >2335Qtation/memoChap.tx<15: Sparc-V9lMe="L3uModelsd="L285" cla5s="line" 5ame="L325"> 325   2336ef="D5c23 = LOAD {*A,x  X*qtation23 = >2336rierd="L286" cla4s="line" 4ame="L351"> 351   23t7ef="D5c23mentation/memory-barrier23men>2337QtatUltraSPARC III Cu User's Manuald="L286" cla4s="line" 4ame="L351"> 351   23t8ef="D5c23ill r:
2338Qtation/memoChap.tx<9: Me="L3uModelsd="L285" cla5s="line" 5ame="L325"> 325   2339ef="D5c23g ses should ncy is f="D23g s>2339atiod="L301" cla5s="line" 5ame="L301"> 301   2345ef="D5c23 = Latas
pte compipcumic23 = >2340QtatUltraSPARC IIIi Processor User's Manuald="L286" cla4s="line" 4ame="L351"> 351   2341ef="D5c23 = Lct"Documesetation/me23 = >2341Qtation/memoChap.tx<8: Me="L3uModelsd="L285" cla5s="line" 5ame="L325"> 325   2342ef="D5c23mentation/memory-barrier23men>2342atiod="L282" cla5s="line" 5ame="L322"> 322   2343ef="D5c23 = LOAD {*A,q,  &ata23 = >23494" iUltraSPARC Architetaurem2005d="L282" cla5s="line" 5ame="L322"> 322   2344ef="D5c23*A = X; Y = if (p)ation/23*A >2344rier would bChap.tx<9: Me="L3d="L282" cla5s="line" 5ame="L322"> 322   2345ef="D5c23*A = X; Y =         q,  23*A >2345Qtation/memoAppendix D: Formal Spntificaii 5smof oma#Me="L3uModelsd="L285" cla5s="line" 5ame="L325"> 325   23 6ef="D5c23AD *B,  X = <ld norma23AD >2346rierd="L286" cla4s="line" 4ame="L351"> 351   23 7ef="D5c23 = LOAD {*A,x  X*qtation23 = >2347QtatUltraSPARC T1 Supple="li #o oma#UltraSPARC Architetaurem2005d="L282" cla5s="line" 5ame="L322"> 322   2348ef="D5c23mentation/memory-barrier23men>2348Qtation/memoChap.tx<8: Me="L3uModelsd="L285" cla5s="line" 5ame="L325"> 325   2349ef="D5c23mentation/memory-barrier23men>2349Qtation/memoAppendix F: Cach s 325   2355ef="D5c23mentg&quBDocume PAIRINGa23men>235h8" id="L318" cla5s="line" 5ame="L338"> 338   2351ef="D5c23mentment-
 351   23m2ef="D5c23mentation/memory-barrier23men>2352Qtation/memoChap.tx<3.3: HaedwareiConsiderne" 5s forLLicks5andd="L301" cla5s="line" 5ame="L301"> 301   2353ef="D5c23 = LWnrnDda _e cos;
2353Qtation/memoooooooooooooooooSynchronizne" 5d="L301" cla5s="line" 5ame="L301"> 301   2354ef="D5c23; Y  305 (2) 5at5tru23; Y>23585" id="L285" cla5s="line" 5ame="L325"> 325   23m5ef="D5c23AD *A,  STORB,  4tation/23AD >23516" iUnix SystemsLforLModernLArchitetaures,iSymmrtric Multiprocession and Cachiond="L285" cla5s="line" 5ame="L325"> 325   23m6ef="D5c23AD *B,  X = < href="D23AD >23m6QtatforLKerldlLProgrammrtsid="L286" cla4s="line" 4ame="L351"> 351   23m7ef="D5c23AD *B,  STORP,  &tat23AD >23m7Qtation/memoChap.tx<13: Oiert Me="L3uModelsd="L285" cla5s="line" 5ame="L325"> 325   2358ef="D5c23*A = X; Y =             23*A >23589" id="L289" cla4s="line" 4ame="L279"> 279int2359ef="D5c23*A = Y = X;












23*A >2359atioIntel Itanium ArchitetauremSoftwareiDeveloper's Manual: Vols=" 1id="L286" cla4s="line" 4ame="L351"> 351   2365ef="D5c23mentation/memory-barrier23men>236eQtation/memoSeta" 5 2.6:oSpecultti 5d="L301" cla5s="line" 5ame="L301"> 301   2361ef="D5c23s spT per dependenclre a23s s>2361Qtation/memoSeta" 5 4.4: Me="L3uAccessd="L301" cla5s="line" 5ame="L301"> 301   2362ef="D5c23and  operati, Q,hat  any23and>2362atio


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