Quelle  cpuacct.c   Sprache: C

// SPDX-License-Identifier: GPL-2.0

/*
 * CPU accounting code for task groups.
 *
 * Based on the work by Paul Menage (menage@google.com) and Balbir Singh
 * (balbir@in.ibm.com).
 */
#include <linux/sched/cputime.h>
#include "sched.h"

/* Time spent by the tasks of the CPU accounting group executing in ... */
enum cpuacct_stat_index {
 CPUACCT_STAT_USER, /* ... user mode */
 CPUACCT_STAT_SYSTEM, /* ... kernel mode */

 CPUACCT_STAT_NSTATS,
};

static const char * const cpuacct_stat_desc[] = {
 [CPUACCT_STAT_USER] = "user",
 [CPUACCT_STAT_SYSTEM] = "system",
};

/* track CPU usage of a group of tasks and its child groups */
struct cpuacct {
 struct cgroup_subsys_state css;
 /* cpuusage holds pointer to a u64-type object on every CPU */
 u64 __percpu *cpuusage;
 struct kernel_cpustat __percpu *cpustat;
};

static inline struct cpuacct *css_ca(struct cgroup_subsys_state *css)
{
 return css ? container_of(css, struct cpuacct, css) : NULL;
}

/* Return CPU accounting group to which this task belongs */
static inline struct cpuacct *task_ca(struct task_struct *tsk)
{
 return css_ca(task_css(tsk, cpuacct_cgrp_id));
}

static inline struct cpuacct *parent_ca(struct cpuacct *ca)
{
 return css_ca(ca->css.parent);
}

static DEFINE_PER_CPU(u64, root_cpuacct_cpuusage);
static struct cpuacct root_cpuacct = {
 .cpustat = &kernel_cpustat,
 .cpuusage = &root_cpuacct_cpuusage,
};

/* Create a new CPU accounting group */
static struct cgroup_subsys_state *
cpuacct_css_alloc(struct cgroup_subsys_state *parent_css)
{
 struct cpuacct *ca;

 if (!parent_css)
  return &root_cpuacct.css;

 ca = kzalloc(sizeof(*ca), GFP_KERNEL);
 if (!ca)
  goto out;

 ca->cpuusage = alloc_percpu(u64);
 if (!ca->cpuusage)
  goto out_free_ca;

 ca->cpustat = alloc_percpu(struct kernel_cpustat);
 if (!ca->cpustat)
  goto out_free_cpuusage;

 return &ca->css;

out_free_cpuusage:
 free_percpu(ca->cpuusage);
out_free_ca:
 kfree(ca);
out:
 return ERR_PTR(-ENOMEM);
}

/* Destroy an existing CPU accounting group */
static void cpuacct_css_free(struct cgroup_subsys_state *css)
{
 struct cpuacct *ca = css_ca(css);

 free_percpu(ca->cpustat);
 free_percpu(ca->cpuusage);
 kfree(ca);
}

static u64 cpuacct_cpuusage_read(struct cpuacct *ca, int cpu,
     enum cpuacct_stat_index index)
{
 u64 *cpuusage = per_cpu_ptr(ca->cpuusage, cpu);
 u64 *cpustat = per_cpu_ptr(ca->cpustat, cpu)->cpustat;
 u64 data;

 /*
 * We allow index == CPUACCT_STAT_NSTATS here to read
 * the sum of usages.
 */
 if (WARN_ON_ONCE(index > CPUACCT_STAT_NSTATS))
  return 0;

#ifndef CONFIG_64BIT
 /*
 * Take rq->lock to make 64-bit read safe on 32-bit platforms.
 */
 raw_spin_rq_lock_irq(cpu_rq(cpu));
#endif

 switch (index) {
 case CPUACCT_STAT_USER:
  data = cpustat[CPUTIME_USER] + cpustat[CPUTIME_NICE];
  break;
 case CPUACCT_STAT_SYSTEM:
  data = cpustat[CPUTIME_SYSTEM] + cpustat[CPUTIME_IRQ] +
   cpustat[CPUTIME_SOFTIRQ];
  break;
 case CPUACCT_STAT_NSTATS:
  data = *cpuusage;
  break;
 }

#ifndef CONFIG_64BIT
 raw_spin_rq_unlock_irq(cpu_rq(cpu));
#endif

 return data;
}

static void cpuacct_cpuusage_write(struct cpuacct *ca, int cpu)
{
 u64 *cpuusage = per_cpu_ptr(ca->cpuusage, cpu);
 u64 *cpustat = per_cpu_ptr(ca->cpustat, cpu)->cpustat;

 /* Don't allow to reset global kernel_cpustat */
 if (ca == &root_cpuacct)
  return;

#ifndef CONFIG_64BIT
 /*
 * Take rq->lock to make 64-bit write safe on 32-bit platforms.
 */
 raw_spin_rq_lock_irq(cpu_rq(cpu));
#endif
 *cpuusage = 0;
 cpustat[CPUTIME_USER] = cpustat[CPUTIME_NICE] = 0;
 cpustat[CPUTIME_SYSTEM] = cpustat[CPUTIME_IRQ] = 0;
 cpustat[CPUTIME_SOFTIRQ] = 0;

#ifndef CONFIG_64BIT
 raw_spin_rq_unlock_irq(cpu_rq(cpu));
#endif
}

/* Return total CPU usage (in nanoseconds) of a group */
static u64 __cpuusage_read(struct cgroup_subsys_state *css,
      enum cpuacct_stat_index index)
{
 struct cpuacct *ca = css_ca(css);
 u64 totalcpuusage = 0;
 int i;

 for_each_possible_cpu(i)
  totalcpuusage += cpuacct_cpuusage_read(ca, i, index);

 return totalcpuusage;
}

static u64 cpuusage_user_read(struct cgroup_subsys_state *css,
         struct cftype *cft)
{
 return __cpuusage_read(css, CPUACCT_STAT_USER);
}

static u64 cpuusage_sys_read(struct cgroup_subsys_state *css,
        struct cftype *cft)
{
 return __cpuusage_read(css, CPUACCT_STAT_SYSTEM);
}

static u64 cpuusage_read(struct cgroup_subsys_state *css, struct cftype *cft)
{
 return __cpuusage_read(css, CPUACCT_STAT_NSTATS);
}

static int cpuusage_write(struct cgroup_subsys_state *css, struct cftype *cft,
     u64 val)
{
 struct cpuacct *ca = css_ca(css);
 int cpu;

 /*
 * Only allow '0' here to do a reset.
 */
 if (val)
  return -EINVAL;

 for_each_possible_cpu(cpu)
  cpuacct_cpuusage_write(ca, cpu);

 return 0;
}

static int __cpuacct_percpu_seq_show(struct seq_file *m,
         enum cpuacct_stat_index index)
{
 struct cpuacct *ca = css_ca(seq_css(m));
 u64 percpu;
 int i;

 for_each_possible_cpu(i) {
  percpu = cpuacct_cpuusage_read(ca, i, index);
  seq_printf(m, "%llu ", (unsigned long long) percpu);
 }
 seq_printf(m, "\n");
 return 0;
}

static int cpuacct_percpu_user_seq_show(struct seq_file *m, void *V)
{
 return __cpuacct_percpu_seq_show(m, CPUACCT_STAT_USER);
}

static int cpuacct_percpu_sys_seq_show(struct seq_file *m, void *V)
{
 return __cpuacct_percpu_seq_show(m, CPUACCT_STAT_SYSTEM);
}

static int cpuacct_percpu_seq_show(struct seq_file *m, void *V)
{
 return __cpuacct_percpu_seq_show(m, CPUACCT_STAT_NSTATS);
}

static int cpuacct_all_seq_show(struct seq_file *m, void *V)
{
 struct cpuacct *ca = css_ca(seq_css(m));
 int index;
 int cpu;

 seq_puts(m, "cpu");
 for (index = 0; index < CPUACCT_STAT_NSTATS; index++)
  seq_printf(m, " %s", cpuacct_stat_desc[index]);
 seq_puts(m, "\n");

 for_each_possible_cpu(cpu) {
  seq_printf(m, "%d", cpu);
  for (index = 0; index < CPUACCT_STAT_NSTATS; index++)
   seq_printf(m, " %llu",
       cpuacct_cpuusage_read(ca, cpu, index));
  seq_puts(m, "\n");
 }
 return 0;
}

static int cpuacct_stats_show(struct seq_file *sf, void *v)
{
 struct cpuacct *ca = css_ca(seq_css(sf));
 struct task_cputime cputime;
 u64 val[CPUACCT_STAT_NSTATS];
 int cpu;
 int stat;

 memset(&cputime, 0, sizeof(cputime));
 for_each_possible_cpu(cpu) {
  u64 *cpustat = per_cpu_ptr(ca->cpustat, cpu)->cpustat;

  cputime.utime += cpustat[CPUTIME_USER];
  cputime.utime += cpustat[CPUTIME_NICE];
  cputime.stime += cpustat[CPUTIME_SYSTEM];
  cputime.stime += cpustat[CPUTIME_IRQ];
  cputime.stime += cpustat[CPUTIME_SOFTIRQ];

  cputime.sum_exec_runtime += *per_cpu_ptr(ca->cpuusage, cpu);
 }

 cputime_adjust(&cputime, &seq_css(sf)->cgroup->prev_cputime,
  &val[CPUACCT_STAT_USER], &val[CPUACCT_STAT_SYSTEM]);

 for (stat = 0; stat < CPUACCT_STAT_NSTATS; stat++) {
  seq_printf(sf, "%s %llu\n", cpuacct_stat_desc[stat],
   nsec_to_clock_t(val[stat]));
 }

 return 0;
}

static struct cftype files[] = {
 {
  .name = "usage",
  .read_u64 = cpuusage_read,
  .write_u64 = cpuusage_write,
 },
 {
  .name = "usage_user",
  .read_u64 = cpuusage_user_read,
 },
 {
  .name = "usage_sys",
  .read_u64 = cpuusage_sys_read,
 },
 {
  .name = "usage_percpu",
  .seq_show = cpuacct_percpu_seq_show,
 },
 {
  .name = "usage_percpu_user",
  .seq_show = cpuacct_percpu_user_seq_show,
 },
 {
  .name = "usage_percpu_sys",
  .seq_show = cpuacct_percpu_sys_seq_show,
 },
 {
  .name = "usage_all",
  .seq_show = cpuacct_all_seq_show,
 },
 {
  .name = "stat",
  .seq_show = cpuacct_stats_show,
 },
 { } /* terminate */
};

/*
 * charge this task's execution time to its accounting group.
 *
 * called with rq->lock held.
 */
void cpuacct_charge(struct task_struct *tsk, u64 cputime)
{
 unsigned int cpu = task_cpu(tsk);
 struct cpuacct *ca;

 lockdep_assert_rq_held(cpu_rq(cpu));

 for (ca = task_ca(tsk); ca; ca = parent_ca(ca))
  *per_cpu_ptr(ca->cpuusage, cpu) += cputime;
}

/*
 * Add user/system time to cpuacct.
 *
 * Note: it's the caller that updates the account of the root cgroup.
 */
void cpuacct_account_field(struct task_struct *tsk, int index, u64 val)
{
 struct cpuacct *ca;

 for (ca = task_ca(tsk); ca != &root_cpuacct; ca = parent_ca(ca))
  __this_cpu_add(ca->cpustat->cpustat[index], val);
}

struct cgroup_subsys cpuacct_cgrp_subsys = {
 .css_alloc = cpuacct_css_alloc,
 .css_free = cpuacct_css_free,
 .legacy_cftypes = files,
 .early_init = true,
};