kernel/sched/cpuacct.c

   1 #include <linux/cgroup.h>
   2 #include <linux/slab.h>
   3 #include <linux/percpu.h>
   4 #include <linux/spinlock.h>
   5 #include <linux/cpumask.h>
   6 #include <linux/seq_file.h>
   7 #include <linux/rcupdate.h>
   8 #include <linux/kernel_stat.h>
   9 #include <linux/err.h>
  10
  11 #include "sched.h"
  12
  13 /*
  14  * CPU accounting code for task groups.
  15  *
  16  * Based on the work by Paul Menage (menage@google.com) and Balbir Singh
  17  * (balbir@in.ibm.com).
  18  */
  19
  20 /* Time spent by the tasks of the cpu accounting group executing in ... */
  21 enum cpuacct_stat_index {
  22         CPUACCT_STAT_USER,      /* ... user mode */
  23         CPUACCT_STAT_SYSTEM,    /* ... kernel mode */
  24
  25         CPUACCT_STAT_NSTATS,
  26 };
  27
  28 /* track cpu usage of a group of tasks and its child groups */
  29 struct cpuacct {
  30         struct cgroup_subsys_state css;
  31         /* cpuusage holds pointer to a u64-type object on every cpu */
  32         u64 __percpu *cpuusage;
  33         struct kernel_cpustat __percpu *cpustat;
  34 };
  35
  36 /* return cpu accounting group corresponding to this container */
  37 static inline struct cpuacct *cgroup_ca(struct cgroup *cgrp)
  38 {
  39         return container_of(cgroup_subsys_state(cgrp, cpuacct_subsys_id),
  40                             struct cpuacct, css);
  41 }
  42
  43 /* return cpu accounting group to which this task belongs */
  44 static inline struct cpuacct *task_ca(struct task_struct *tsk)
  45 {
  46         return container_of(task_subsys_state(tsk, cpuacct_subsys_id),
  47                             struct cpuacct, css);
  48 }
  49
  50 static inline struct cpuacct *__parent_ca(struct cpuacct *ca)
  51 {
  52         return cgroup_ca(ca->css.cgroup->parent);
  53 }
  54
  55 static inline struct cpuacct *parent_ca(struct cpuacct *ca)
  56 {
  57         if (!ca->css.cgroup->parent)
  58                 return NULL;
  59         return cgroup_ca(ca->css.cgroup->parent);
  60 }
  61
  62 static DEFINE_PER_CPU(u64, root_cpuacct_cpuusage);
  63 static struct cpuacct root_cpuacct = {
  64         .cpustat        = &kernel_cpustat,
  65         .cpuusage       = &root_cpuacct_cpuusage,
  66 };
  67
  68 /* create a new cpu accounting group */
  69 static struct cgroup_subsys_state *cpuacct_css_alloc(struct cgroup *cgrp)
  70 {
  71         struct cpuacct *ca;
  72
  73         if (!cgrp->parent)
  74                 return &root_cpuacct.css;
  75
  76         ca = kzalloc(sizeof(*ca), GFP_KERNEL);
  77         if (!ca)
  78                 goto out;
  79
  80         ca->cpuusage = alloc_percpu(u64);
  81         if (!ca->cpuusage)
  82                 goto out_free_ca;
  83
  84         ca->cpustat = alloc_percpu(struct kernel_cpustat);
  85         if (!ca->cpustat)
  86                 goto out_free_cpuusage;
  87
  88         return &ca->css;
  89
  90 out_free_cpuusage:
  91         free_percpu(ca->cpuusage);
  92 out_free_ca:
  93         kfree(ca);
  94 out:
  95         return ERR_PTR(-ENOMEM);
  96 }
  97
  98 /* destroy an existing cpu accounting group */
  99 static void cpuacct_css_free(struct cgroup *cgrp)
 100 {
 101         struct cpuacct *ca = cgroup_ca(cgrp);
 102
 103         free_percpu(ca->cpustat);
 104         free_percpu(ca->cpuusage);
 105         kfree(ca);
 106 }
 107
 108 static u64 cpuacct_cpuusage_read(struct cpuacct *ca, int cpu)
 109 {
 110         u64 *cpuusage = per_cpu_ptr(ca->cpuusage, cpu);
 111         u64 data;
 112
 113 #ifndef CONFIG_64BIT
 114         /*
 115          * Take rq->lock to make 64-bit read safe on 32-bit platforms.
 116          */
 117         raw_spin_lock_irq(&cpu_rq(cpu)->lock);
 118         data = *cpuusage;
 119         raw_spin_unlock_irq(&cpu_rq(cpu)->lock);
 120 #else
 121         data = *cpuusage;
 122 #endif
 123
 124         return data;
 125 }
 126
 127 static void cpuacct_cpuusage_write(struct cpuacct *ca, int cpu, u64 val)
 128 {
 129         u64 *cpuusage = per_cpu_ptr(ca->cpuusage, cpu);
 130
 131 #ifndef CONFIG_64BIT
 132         /*
 133          * Take rq->lock to make 64-bit write safe on 32-bit platforms.
 134          */
 135         raw_spin_lock_irq(&cpu_rq(cpu)->lock);
 136         *cpuusage = val;
 137         raw_spin_unlock_irq(&cpu_rq(cpu)->lock);
 138 #else
 139         *cpuusage = val;
 140 #endif
 141 }
 142
 143 /* return total cpu usage (in nanoseconds) of a group */
 144 static u64 cpuusage_read(struct cgroup *cgrp, struct cftype *cft)
 145 {
 146         struct cpuacct *ca = cgroup_ca(cgrp);
 147         u64 totalcpuusage = 0;
 148         int i;
 149
 150         for_each_present_cpu(i)
 151                 totalcpuusage += cpuacct_cpuusage_read(ca, i);
 152
 153         return totalcpuusage;
 154 }
 155
 156 static int cpuusage_write(struct cgroup *cgrp, struct cftype *cftype,
 157                                                                 u64 reset)
 158 {
 159         struct cpuacct *ca = cgroup_ca(cgrp);
 160         int err = 0;
 161         int i;
 162
 163         if (reset) {
 164                 err = -EINVAL;
 165                 goto out;
 166         }
 167
 168         for_each_present_cpu(i)
 169                 cpuacct_cpuusage_write(ca, i, 0);
 170
 171 out:
 172         return err;
 173 }
 174
 175 static int cpuacct_percpu_seq_read(struct cgroup *cgroup, struct cftype *cft,
 176                                    struct seq_file *m)
 177 {
 178         struct cpuacct *ca = cgroup_ca(cgroup);
 179         u64 percpu;
 180         int i;
 181
 182         for_each_present_cpu(i) {
 183                 percpu = cpuacct_cpuusage_read(ca, i);
 184                 seq_printf(m, "%llu ", (unsigned long long) percpu);
 185         }
 186         seq_printf(m, "\n");
 187         return 0;
 188 }
 189
 190 static const char * const cpuacct_stat_desc[] = {
 191         [CPUACCT_STAT_USER] = "user",
 192         [CPUACCT_STAT_SYSTEM] = "system",
 193 };
 194
 195 static int cpuacct_stats_show(struct cgroup *cgrp, struct cftype *cft,
 196                               struct cgroup_map_cb *cb)
 197 {
 198         struct cpuacct *ca = cgroup_ca(cgrp);
 199         int cpu;
 200         s64 val = 0;
 201
 202         for_each_online_cpu(cpu) {
 203                 struct kernel_cpustat *kcpustat = per_cpu_ptr(ca->cpustat, cpu);
 204                 val += kcpustat->cpustat[CPUTIME_USER];
 205                 val += kcpustat->cpustat[CPUTIME_NICE];
 206         }
 207         val = cputime64_to_clock_t(val);
 208         cb->fill(cb, cpuacct_stat_desc[CPUACCT_STAT_USER], val);
 209
 210         val = 0;
 211         for_each_online_cpu(cpu) {
 212                 struct kernel_cpustat *kcpustat = per_cpu_ptr(ca->cpustat, cpu);
 213                 val += kcpustat->cpustat[CPUTIME_SYSTEM];
 214                 val += kcpustat->cpustat[CPUTIME_IRQ];
 215                 val += kcpustat->cpustat[CPUTIME_SOFTIRQ];
 216         }
 217
 218         val = cputime64_to_clock_t(val);
 219         cb->fill(cb, cpuacct_stat_desc[CPUACCT_STAT_SYSTEM], val);
 220
 221         return 0;
 222 }
 223
 224 static struct cftype files[] = {
 225         {
 226                 .name = "usage",
 227                 .read_u64 = cpuusage_read,
 228                 .write_u64 = cpuusage_write,
 229         },
 230         {
 231                 .name = "usage_percpu",
 232                 .read_seq_string = cpuacct_percpu_seq_read,
 233         },
 234         {
 235                 .name = "stat",
 236                 .read_map = cpuacct_stats_show,
 237         },
 238         { }     /* terminate */
 239 };
 240
 241 /*
 242  * charge this task's execution time to its accounting group.
 243  *
 244  * called with rq->lock held.
 245  */
 246 void cpuacct_charge(struct task_struct *tsk, u64 cputime)
 247 {
 248         struct cpuacct *ca;
 249         int cpu;
 250
 251         cpu = task_cpu(tsk);
 252
 253         rcu_read_lock();
 254
 255         ca = task_ca(tsk);
 256
 257         while (true) {
 258                 u64 *cpuusage = per_cpu_ptr(ca->cpuusage, cpu);
 259                 *cpuusage += cputime;
 260
 261                 ca = parent_ca(ca);
 262                 if (!ca)
 263                         break;
 264         }
 265
 266         rcu_read_unlock();
 267 }
 268
 269 /*
 270  * Add user/system time to cpuacct.
 271  *
 272  * Note: it's the caller that updates the account of the root cgroup.
 273  */
 274 void cpuacct_account_field(struct task_struct *p, int index, u64 val)
 275 {
 276         struct kernel_cpustat *kcpustat;
 277         struct cpuacct *ca;
 278
 279         rcu_read_lock();
 280         ca = task_ca(p);
 281         while (ca != &root_cpuacct) {
 282                 kcpustat = this_cpu_ptr(ca->cpustat);
 283                 kcpustat->cpustat[index] += val;
 284                 ca = __parent_ca(ca);
 285         }
 286         rcu_read_unlock();
 287 }
 288
 289 struct cgroup_subsys cpuacct_subsys = {
 290         .name           = "cpuacct",
 291         .css_alloc      = cpuacct_css_alloc,
 292         .css_free       = cpuacct_css_free,
 293         .subsys_id      = cpuacct_subsys_id,
 294         .base_cftypes   = files,
 295         .early_init     = 1,
 296 };