1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37#include <linux/module.h>
38#include <net/tcp.h>
39
40
41#define LP_RESOL TCP_TS_HZ
42
43
44
45
46
47
48
49
50
51
52
53enum tcp_lp_state {
54 LP_VALID_RHZ = (1 << 0),
55 LP_VALID_OWD = (1 << 1),
56 LP_WITHIN_THR = (1 << 3),
57 LP_WITHIN_INF = (1 << 4),
58};
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77struct lp {
78 u32 flag;
79 u32 sowd;
80 u32 owd_min;
81 u32 owd_max;
82 u32 owd_max_rsv;
83 u32 remote_hz;
84 u32 remote_ref_time;
85 u32 local_ref_time;
86 u32 last_drop;
87 u32 inference;
88};
89
90
91
92
93
94
95
96
97static void tcp_lp_init(struct sock *sk)
98{
99 struct lp *lp = inet_csk_ca(sk);
100
101 lp->flag = 0;
102 lp->sowd = 0;
103 lp->owd_min = 0xffffffff;
104 lp->owd_max = 0;
105 lp->owd_max_rsv = 0;
106 lp->remote_hz = 0;
107 lp->remote_ref_time = 0;
108 lp->local_ref_time = 0;
109 lp->last_drop = 0;
110 lp->inference = 0;
111}
112
113
114
115
116
117
118
119
120
121static void tcp_lp_cong_avoid(struct sock *sk, u32 ack, u32 acked)
122{
123 struct lp *lp = inet_csk_ca(sk);
124
125 if (!(lp->flag & LP_WITHIN_INF))
126 tcp_reno_cong_avoid(sk, ack, acked);
127}
128
129
130
131
132
133
134
135
136
137static u32 tcp_lp_remote_hz_estimator(struct sock *sk)
138{
139 struct tcp_sock *tp = tcp_sk(sk);
140 struct lp *lp = inet_csk_ca(sk);
141 s64 rhz = lp->remote_hz << 6;
142 s64 m = 0;
143
144
145
146 if (lp->remote_ref_time == 0 || lp->local_ref_time == 0)
147 goto out;
148
149
150 if (tp->rx_opt.rcv_tsval == lp->remote_ref_time ||
151 tp->rx_opt.rcv_tsecr == lp->local_ref_time)
152 goto out;
153
154 m = TCP_TS_HZ *
155 (tp->rx_opt.rcv_tsval - lp->remote_ref_time) /
156 (tp->rx_opt.rcv_tsecr - lp->local_ref_time);
157 if (m < 0)
158 m = -m;
159
160 if (rhz > 0) {
161 m -= rhz >> 6;
162 rhz += m;
163 } else
164 rhz = m << 6;
165
166 out:
167
168 if ((rhz >> 6) > 0)
169 lp->flag |= LP_VALID_RHZ;
170 else
171 lp->flag &= ~LP_VALID_RHZ;
172
173
174 lp->remote_ref_time = tp->rx_opt.rcv_tsval;
175 lp->local_ref_time = tp->rx_opt.rcv_tsecr;
176
177 return rhz >> 6;
178}
179
180
181
182
183
184
185
186
187
188
189
190
191static u32 tcp_lp_owd_calculator(struct sock *sk)
192{
193 struct tcp_sock *tp = tcp_sk(sk);
194 struct lp *lp = inet_csk_ca(sk);
195 s64 owd = 0;
196
197 lp->remote_hz = tcp_lp_remote_hz_estimator(sk);
198
199 if (lp->flag & LP_VALID_RHZ) {
200 owd =
201 tp->rx_opt.rcv_tsval * (LP_RESOL / lp->remote_hz) -
202 tp->rx_opt.rcv_tsecr * (LP_RESOL / TCP_TS_HZ);
203 if (owd < 0)
204 owd = -owd;
205 }
206
207 if (owd > 0)
208 lp->flag |= LP_VALID_OWD;
209 else
210 lp->flag &= ~LP_VALID_OWD;
211
212 return owd;
213}
214
215
216
217
218
219
220
221
222
223
224
225
226
227static void tcp_lp_rtt_sample(struct sock *sk, u32 rtt)
228{
229 struct lp *lp = inet_csk_ca(sk);
230 s64 mowd = tcp_lp_owd_calculator(sk);
231
232
233 if (!(lp->flag & LP_VALID_RHZ) || !(lp->flag & LP_VALID_OWD))
234 return;
235
236
237 if (mowd < lp->owd_min)
238 lp->owd_min = mowd;
239
240
241
242 if (mowd > lp->owd_max) {
243 if (mowd > lp->owd_max_rsv) {
244 if (lp->owd_max_rsv == 0)
245 lp->owd_max = mowd;
246 else
247 lp->owd_max = lp->owd_max_rsv;
248 lp->owd_max_rsv = mowd;
249 } else
250 lp->owd_max = mowd;
251 }
252
253
254 if (lp->sowd != 0) {
255 mowd -= lp->sowd >> 3;
256 lp->sowd += mowd;
257 } else
258 lp->sowd = mowd << 3;
259}
260
261
262
263
264
265
266
267
268
269
270
271static void tcp_lp_pkts_acked(struct sock *sk, const struct ack_sample *sample)
272{
273 struct tcp_sock *tp = tcp_sk(sk);
274 struct lp *lp = inet_csk_ca(sk);
275 u32 now = tcp_time_stamp(tp);
276 u32 delta;
277
278 if (sample->rtt_us > 0)
279 tcp_lp_rtt_sample(sk, sample->rtt_us);
280
281
282 delta = now - tp->rx_opt.rcv_tsecr;
283 if ((s32)delta > 0)
284 lp->inference = 3 * delta;
285
286
287 if (lp->last_drop && (now - lp->last_drop < lp->inference))
288 lp->flag |= LP_WITHIN_INF;
289 else
290 lp->flag &= ~LP_WITHIN_INF;
291
292
293 if (lp->sowd >> 3 <
294 lp->owd_min + 15 * (lp->owd_max - lp->owd_min) / 100)
295 lp->flag |= LP_WITHIN_THR;
296 else
297 lp->flag &= ~LP_WITHIN_THR;
298
299 pr_debug("TCP-LP: %05o|%5u|%5u|%15u|%15u|%15u\n", lp->flag,
300 tp->snd_cwnd, lp->remote_hz, lp->owd_min, lp->owd_max,
301 lp->sowd >> 3);
302
303 if (lp->flag & LP_WITHIN_THR)
304 return;
305
306
307
308
309 lp->owd_min = lp->sowd >> 3;
310 lp->owd_max = lp->sowd >> 2;
311 lp->owd_max_rsv = lp->sowd >> 2;
312
313
314
315 if (lp->flag & LP_WITHIN_INF)
316 tp->snd_cwnd = 1U;
317
318
319
320 else
321 tp->snd_cwnd = max(tp->snd_cwnd >> 1U, 1U);
322
323
324 lp->last_drop = now;
325}
326
327static struct tcp_congestion_ops tcp_lp __read_mostly = {
328 .init = tcp_lp_init,
329 .ssthresh = tcp_reno_ssthresh,
330 .undo_cwnd = tcp_reno_undo_cwnd,
331 .cong_avoid = tcp_lp_cong_avoid,
332 .pkts_acked = tcp_lp_pkts_acked,
333
334 .owner = THIS_MODULE,
335 .name = "lp"
336};
337
338static int __init tcp_lp_register(void)
339{
340 BUILD_BUG_ON(sizeof(struct lp) > ICSK_CA_PRIV_SIZE);
341 return tcp_register_congestion_control(&tcp_lp);
342}
343
344static void __exit tcp_lp_unregister(void)
345{
346 tcp_unregister_congestion_control(&tcp_lp);
347}
348
349module_init(tcp_lp_register);
350module_exit(tcp_lp_unregister);
351
352MODULE_AUTHOR("Wong Hoi Sing Edison, Hung Hing Lun Mike");
353MODULE_LICENSE("GPL");
354MODULE_DESCRIPTION("TCP Low Priority");
355