linux/kernel/sched/cpuacct.c
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   1// SPDX-License-Identifier: GPL-2.0
   2/*
   3 * CPU accounting code for task groups.
   4 *
   5 * Based on the work by Paul Menage (menage@google.com) and Balbir Singh
   6 * (balbir@in.ibm.com).
   7 */
   8#include <asm/irq_regs.h>
   9#include "sched.h"
  10
  11/* Time spent by the tasks of the CPU accounting group executing in ... */
  12enum cpuacct_stat_index {
  13        CPUACCT_STAT_USER,      /* ... user mode */
  14        CPUACCT_STAT_SYSTEM,    /* ... kernel mode */
  15
  16        CPUACCT_STAT_NSTATS,
  17};
  18
  19static const char * const cpuacct_stat_desc[] = {
  20        [CPUACCT_STAT_USER] = "user",
  21        [CPUACCT_STAT_SYSTEM] = "system",
  22};
  23
  24struct cpuacct_usage {
  25        u64     usages[CPUACCT_STAT_NSTATS];
  26};
  27
  28/* track CPU usage of a group of tasks and its child groups */
  29struct cpuacct {
  30        struct cgroup_subsys_state      css;
  31        /* cpuusage holds pointer to a u64-type object on every CPU */
  32        struct cpuacct_usage __percpu   *cpuusage;
  33        struct kernel_cpustat __percpu  *cpustat;
  34};
  35
  36static inline struct cpuacct *css_ca(struct cgroup_subsys_state *css)
  37{
  38        return css ? container_of(css, struct cpuacct, css) : NULL;
  39}
  40
  41/* Return CPU accounting group to which this task belongs */
  42static inline struct cpuacct *task_ca(struct task_struct *tsk)
  43{
  44        return css_ca(task_css(tsk, cpuacct_cgrp_id));
  45}
  46
  47static inline struct cpuacct *parent_ca(struct cpuacct *ca)
  48{
  49        return css_ca(ca->css.parent);
  50}
  51
  52static DEFINE_PER_CPU(struct cpuacct_usage, root_cpuacct_cpuusage);
  53static struct cpuacct root_cpuacct = {
  54        .cpustat        = &kernel_cpustat,
  55        .cpuusage       = &root_cpuacct_cpuusage,
  56};
  57
  58/* Create a new CPU accounting group */
  59static struct cgroup_subsys_state *
  60cpuacct_css_alloc(struct cgroup_subsys_state *parent_css)
  61{
  62        struct cpuacct *ca;
  63
  64        if (!parent_css)
  65                return &root_cpuacct.css;
  66
  67        ca = kzalloc(sizeof(*ca), GFP_KERNEL);
  68        if (!ca)
  69                goto out;
  70
  71        ca->cpuusage = alloc_percpu(struct cpuacct_usage);
  72        if (!ca->cpuusage)
  73                goto out_free_ca;
  74
  75        ca->cpustat = alloc_percpu(struct kernel_cpustat);
  76        if (!ca->cpustat)
  77                goto out_free_cpuusage;
  78
  79        return &ca->css;
  80
  81out_free_cpuusage:
  82        free_percpu(ca->cpuusage);
  83out_free_ca:
  84        kfree(ca);
  85out:
  86        return ERR_PTR(-ENOMEM);
  87}
  88
  89/* Destroy an existing CPU accounting group */
  90static void cpuacct_css_free(struct cgroup_subsys_state *css)
  91{
  92        struct cpuacct *ca = css_ca(css);
  93
  94        free_percpu(ca->cpustat);
  95        free_percpu(ca->cpuusage);
  96        kfree(ca);
  97}
  98
  99static u64 cpuacct_cpuusage_read(struct cpuacct *ca, int cpu,
 100                                 enum cpuacct_stat_index index)
 101{
 102        struct cpuacct_usage *cpuusage = per_cpu_ptr(ca->cpuusage, cpu);
 103        u64 data;
 104
 105        /*
 106         * We allow index == CPUACCT_STAT_NSTATS here to read
 107         * the sum of usages.
 108         */
 109        BUG_ON(index > CPUACCT_STAT_NSTATS);
 110
 111#ifndef CONFIG_64BIT
 112        /*
 113         * Take rq->lock to make 64-bit read safe on 32-bit platforms.
 114         */
 115        raw_spin_rq_lock_irq(cpu_rq(cpu));
 116#endif
 117
 118        if (index == CPUACCT_STAT_NSTATS) {
 119                int i = 0;
 120
 121                data = 0;
 122                for (i = 0; i < CPUACCT_STAT_NSTATS; i++)
 123                        data += cpuusage->usages[i];
 124        } else {
 125                data = cpuusage->usages[index];
 126        }
 127
 128#ifndef CONFIG_64BIT
 129        raw_spin_rq_unlock_irq(cpu_rq(cpu));
 130#endif
 131
 132        return data;
 133}
 134
 135static void cpuacct_cpuusage_write(struct cpuacct *ca, int cpu, u64 val)
 136{
 137        struct cpuacct_usage *cpuusage = per_cpu_ptr(ca->cpuusage, cpu);
 138        int i;
 139
 140#ifndef CONFIG_64BIT
 141        /*
 142         * Take rq->lock to make 64-bit write safe on 32-bit platforms.
 143         */
 144        raw_spin_rq_lock_irq(cpu_rq(cpu));
 145#endif
 146
 147        for (i = 0; i < CPUACCT_STAT_NSTATS; i++)
 148                cpuusage->usages[i] = val;
 149
 150#ifndef CONFIG_64BIT
 151        raw_spin_rq_unlock_irq(cpu_rq(cpu));
 152#endif
 153}
 154
 155/* Return total CPU usage (in nanoseconds) of a group */
 156static u64 __cpuusage_read(struct cgroup_subsys_state *css,
 157                           enum cpuacct_stat_index index)
 158{
 159        struct cpuacct *ca = css_ca(css);
 160        u64 totalcpuusage = 0;
 161        int i;
 162
 163        for_each_possible_cpu(i)
 164                totalcpuusage += cpuacct_cpuusage_read(ca, i, index);
 165
 166        return totalcpuusage;
 167}
 168
 169static u64 cpuusage_user_read(struct cgroup_subsys_state *css,
 170                              struct cftype *cft)
 171{
 172        return __cpuusage_read(css, CPUACCT_STAT_USER);
 173}
 174
 175static u64 cpuusage_sys_read(struct cgroup_subsys_state *css,
 176                             struct cftype *cft)
 177{
 178        return __cpuusage_read(css, CPUACCT_STAT_SYSTEM);
 179}
 180
 181static u64 cpuusage_read(struct cgroup_subsys_state *css, struct cftype *cft)
 182{
 183        return __cpuusage_read(css, CPUACCT_STAT_NSTATS);
 184}
 185
 186static int cpuusage_write(struct cgroup_subsys_state *css, struct cftype *cft,
 187                          u64 val)
 188{
 189        struct cpuacct *ca = css_ca(css);
 190        int cpu;
 191
 192        /*
 193         * Only allow '0' here to do a reset.
 194         */
 195        if (val)
 196                return -EINVAL;
 197
 198        for_each_possible_cpu(cpu)
 199                cpuacct_cpuusage_write(ca, cpu, 0);
 200
 201        return 0;
 202}
 203
 204static int __cpuacct_percpu_seq_show(struct seq_file *m,
 205                                     enum cpuacct_stat_index index)
 206{
 207        struct cpuacct *ca = css_ca(seq_css(m));
 208        u64 percpu;
 209        int i;
 210
 211        for_each_possible_cpu(i) {
 212                percpu = cpuacct_cpuusage_read(ca, i, index);
 213                seq_printf(m, "%llu ", (unsigned long long) percpu);
 214        }
 215        seq_printf(m, "\n");
 216        return 0;
 217}
 218
 219static int cpuacct_percpu_user_seq_show(struct seq_file *m, void *V)
 220{
 221        return __cpuacct_percpu_seq_show(m, CPUACCT_STAT_USER);
 222}
 223
 224static int cpuacct_percpu_sys_seq_show(struct seq_file *m, void *V)
 225{
 226        return __cpuacct_percpu_seq_show(m, CPUACCT_STAT_SYSTEM);
 227}
 228
 229static int cpuacct_percpu_seq_show(struct seq_file *m, void *V)
 230{
 231        return __cpuacct_percpu_seq_show(m, CPUACCT_STAT_NSTATS);
 232}
 233
 234static int cpuacct_all_seq_show(struct seq_file *m, void *V)
 235{
 236        struct cpuacct *ca = css_ca(seq_css(m));
 237        int index;
 238        int cpu;
 239
 240        seq_puts(m, "cpu");
 241        for (index = 0; index < CPUACCT_STAT_NSTATS; index++)
 242                seq_printf(m, " %s", cpuacct_stat_desc[index]);
 243        seq_puts(m, "\n");
 244
 245        for_each_possible_cpu(cpu) {
 246                struct cpuacct_usage *cpuusage = per_cpu_ptr(ca->cpuusage, cpu);
 247
 248                seq_printf(m, "%d", cpu);
 249
 250                for (index = 0; index < CPUACCT_STAT_NSTATS; index++) {
 251#ifndef CONFIG_64BIT
 252                        /*
 253                         * Take rq->lock to make 64-bit read safe on 32-bit
 254                         * platforms.
 255                         */
 256                        raw_spin_rq_lock_irq(cpu_rq(cpu));
 257#endif
 258
 259                        seq_printf(m, " %llu", cpuusage->usages[index]);
 260
 261#ifndef CONFIG_64BIT
 262                        raw_spin_rq_unlock_irq(cpu_rq(cpu));
 263#endif
 264                }
 265                seq_puts(m, "\n");
 266        }
 267        return 0;
 268}
 269
 270static int cpuacct_stats_show(struct seq_file *sf, void *v)
 271{
 272        struct cpuacct *ca = css_ca(seq_css(sf));
 273        s64 val[CPUACCT_STAT_NSTATS];
 274        int cpu;
 275        int stat;
 276
 277        memset(val, 0, sizeof(val));
 278        for_each_possible_cpu(cpu) {
 279                u64 *cpustat = per_cpu_ptr(ca->cpustat, cpu)->cpustat;
 280
 281                val[CPUACCT_STAT_USER]   += cpustat[CPUTIME_USER];
 282                val[CPUACCT_STAT_USER]   += cpustat[CPUTIME_NICE];
 283                val[CPUACCT_STAT_SYSTEM] += cpustat[CPUTIME_SYSTEM];
 284                val[CPUACCT_STAT_SYSTEM] += cpustat[CPUTIME_IRQ];
 285                val[CPUACCT_STAT_SYSTEM] += cpustat[CPUTIME_SOFTIRQ];
 286        }
 287
 288        for (stat = 0; stat < CPUACCT_STAT_NSTATS; stat++) {
 289                seq_printf(sf, "%s %lld\n",
 290                           cpuacct_stat_desc[stat],
 291                           (long long)nsec_to_clock_t(val[stat]));
 292        }
 293
 294        return 0;
 295}
 296
 297static struct cftype files[] = {
 298        {
 299                .name = "usage",
 300                .read_u64 = cpuusage_read,
 301                .write_u64 = cpuusage_write,
 302        },
 303        {
 304                .name = "usage_user",
 305                .read_u64 = cpuusage_user_read,
 306        },
 307        {
 308                .name = "usage_sys",
 309                .read_u64 = cpuusage_sys_read,
 310        },
 311        {
 312                .name = "usage_percpu",
 313                .seq_show = cpuacct_percpu_seq_show,
 314        },
 315        {
 316                .name = "usage_percpu_user",
 317                .seq_show = cpuacct_percpu_user_seq_show,
 318        },
 319        {
 320                .name = "usage_percpu_sys",
 321                .seq_show = cpuacct_percpu_sys_seq_show,
 322        },
 323        {
 324                .name = "usage_all",
 325                .seq_show = cpuacct_all_seq_show,
 326        },
 327        {
 328                .name = "stat",
 329                .seq_show = cpuacct_stats_show,
 330        },
 331        { }     /* terminate */
 332};
 333
 334/*
 335 * charge this task's execution time to its accounting group.
 336 *
 337 * called with rq->lock held.
 338 */
 339void cpuacct_charge(struct task_struct *tsk, u64 cputime)
 340{
 341        struct cpuacct *ca;
 342        int index = CPUACCT_STAT_SYSTEM;
 343        struct pt_regs *regs = get_irq_regs() ? : task_pt_regs(tsk);
 344
 345        if (regs && user_mode(regs))
 346                index = CPUACCT_STAT_USER;
 347
 348        rcu_read_lock();
 349
 350        for (ca = task_ca(tsk); ca; ca = parent_ca(ca))
 351                __this_cpu_add(ca->cpuusage->usages[index], cputime);
 352
 353        rcu_read_unlock();
 354}
 355
 356/*
 357 * Add user/system time to cpuacct.
 358 *
 359 * Note: it's the caller that updates the account of the root cgroup.
 360 */
 361void cpuacct_account_field(struct task_struct *tsk, int index, u64 val)
 362{
 363        struct cpuacct *ca;
 364
 365        rcu_read_lock();
 366        for (ca = task_ca(tsk); ca != &root_cpuacct; ca = parent_ca(ca))
 367                __this_cpu_add(ca->cpustat->cpustat[index], val);
 368        rcu_read_unlock();
 369}
 370
 371struct cgroup_subsys cpuacct_cgrp_subsys = {
 372        .css_alloc      = cpuacct_css_alloc,
 373        .css_free       = cpuacct_css_free,
 374        .legacy_cftypes = files,
 375        .early_init     = true,
 376};
 377
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