kernel/sched/cpuacct.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 #include <linux/cgroup.h>
   3 #include <linux/slab.h>
   4 #include <linux/percpu.h>
   5 #include <linux/spinlock.h>
   6 #include <linux/cpumask.h>
   7 #include <linux/seq_file.h>
   8 #include <linux/rcupdate.h>
   9 #include <linux/kernel_stat.h>
  10 #include <linux/err.h>
  11
  12 #include "sched.h"
  13
  14 /*
  15  * CPU accounting code for task groups.
  16  *
  17  * Based on the work by Paul Menage (menage@google.com) and Balbir Singh
  18  * (balbir@in.ibm.com).
  19  */
  20
  21 /* Time spent by the tasks of the cpu accounting group executing in ... */
  22 enum cpuacct_stat_index {
  23         CPUACCT_STAT_USER,      /* ... user mode */
  24         CPUACCT_STAT_SYSTEM,    /* ... kernel mode */
  25
  26         CPUACCT_STAT_NSTATS,
  27 };
  28
  29 static const char * const cpuacct_stat_desc[] = {
  30         [CPUACCT_STAT_USER] = "user",
  31         [CPUACCT_STAT_SYSTEM] = "system",
  32 };
  33
  34 struct cpuacct_usage {
  35         u64     usages[CPUACCT_STAT_NSTATS];
  36 };
  37
  38 /* track cpu usage of a group of tasks and its child groups */
  39 struct cpuacct {
  40         struct cgroup_subsys_state css;
  41         /* cpuusage holds pointer to a u64-type object on every cpu */
  42         struct cpuacct_usage __percpu *cpuusage;
  43         struct kernel_cpustat __percpu *cpustat;
  44 };
  45
  46 static inline struct cpuacct *css_ca(struct cgroup_subsys_state *css)
  47 {
  48         return css ? container_of(css, struct cpuacct, css) : NULL;
  49 }
  50
  51 /* return cpu accounting group to which this task belongs */
  52 static inline struct cpuacct *task_ca(struct task_struct *tsk)
  53 {
  54         return css_ca(task_css(tsk, cpuacct_cgrp_id));
  55 }
  56
  57 static inline struct cpuacct *parent_ca(struct cpuacct *ca)
  58 {
  59         return css_ca(ca->css.parent);
  60 }
  61
  62 static DEFINE_PER_CPU(struct cpuacct_usage, 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 *
  70 cpuacct_css_alloc(struct cgroup_subsys_state *parent_css)
  71 {
  72         struct cpuacct *ca;
  73
  74         if (!parent_css)
  75                 return &root_cpuacct.css;
  76
  77         ca = kzalloc(sizeof(*ca), GFP_KERNEL);
  78         if (!ca)
  79                 goto out;
  80
  81         ca->cpuusage = alloc_percpu(struct cpuacct_usage);
  82         if (!ca->cpuusage)
  83                 goto out_free_ca;
  84
  85         ca->cpustat = alloc_percpu(struct kernel_cpustat);
  86         if (!ca->cpustat)
  87                 goto out_free_cpuusage;
  88
  89         return &ca->css;
  90
  91 out_free_cpuusage:
  92         free_percpu(ca->cpuusage);
  93 out_free_ca:
  94         kfree(ca);
  95 out:
  96         return ERR_PTR(-ENOMEM);
  97 }
  98
  99 /* destroy an existing cpu accounting group */
 100 static void cpuacct_css_free(struct cgroup_subsys_state *css)
 101 {
 102         struct cpuacct *ca = css_ca(css);
 103
 104         free_percpu(ca->cpustat);
 105         free_percpu(ca->cpuusage);
 106         kfree(ca);
 107 }
 108
 109 static u64 cpuacct_cpuusage_read(struct cpuacct *ca, int cpu,
 110                                  enum cpuacct_stat_index index)
 111 {
 112         struct cpuacct_usage *cpuusage = per_cpu_ptr(ca->cpuusage, cpu);
 113         u64 data;
 114
 115         /*
 116          * We allow index == CPUACCT_STAT_NSTATS here to read
 117          * the sum of suages.
 118          */
 119         BUG_ON(index > CPUACCT_STAT_NSTATS);
 120
 121 #ifndef CONFIG_64BIT
 122         /*
 123          * Take rq->lock to make 64-bit read safe on 32-bit platforms.
 124          */
 125         raw_spin_lock_irq(&cpu_rq(cpu)->lock);
 126 #endif
 127
 128         if (index == CPUACCT_STAT_NSTATS) {
 129                 int i = 0;
 130
 131                 data = 0;
 132                 for (i = 0; i < CPUACCT_STAT_NSTATS; i++)
 133                         data += cpuusage->usages[i];
 134         } else {
 135                 data = cpuusage->usages[index];
 136         }
 137
 138 #ifndef CONFIG_64BIT
 139         raw_spin_unlock_irq(&cpu_rq(cpu)->lock);
 140 #endif
 141
 142         return data;
 143 }
 144
 145 static void cpuacct_cpuusage_write(struct cpuacct *ca, int cpu, u64 val)
 146 {
 147         struct cpuacct_usage *cpuusage = per_cpu_ptr(ca->cpuusage, cpu);
 148         int i;
 149
 150 #ifndef CONFIG_64BIT
 151         /*
 152          * Take rq->lock to make 64-bit write safe on 32-bit platforms.
 153          */
 154         raw_spin_lock_irq(&cpu_rq(cpu)->lock);
 155 #endif
 156
 157         for (i = 0; i < CPUACCT_STAT_NSTATS; i++)
 158                 cpuusage->usages[i] = val;
 159
 160 #ifndef CONFIG_64BIT
 161         raw_spin_unlock_irq(&cpu_rq(cpu)->lock);
 162 #endif
 163 }
 164
 165 /* return total cpu usage (in nanoseconds) of a group */
 166 static u64 __cpuusage_read(struct cgroup_subsys_state *css,
 167                            enum cpuacct_stat_index index)
 168 {
 169         struct cpuacct *ca = css_ca(css);
 170         u64 totalcpuusage = 0;
 171         int i;
 172
 173         for_each_possible_cpu(i)
 174                 totalcpuusage += cpuacct_cpuusage_read(ca, i, index);
 175
 176         return totalcpuusage;
 177 }
 178
 179 static u64 cpuusage_user_read(struct cgroup_subsys_state *css,
 180                               struct cftype *cft)
 181 {
 182         return __cpuusage_read(css, CPUACCT_STAT_USER);
 183 }
 184
 185 static u64 cpuusage_sys_read(struct cgroup_subsys_state *css,
 186                              struct cftype *cft)
 187 {
 188         return __cpuusage_read(css, CPUACCT_STAT_SYSTEM);
 189 }
 190
 191 static u64 cpuusage_read(struct cgroup_subsys_state *css, struct cftype *cft)
 192 {
 193         return __cpuusage_read(css, CPUACCT_STAT_NSTATS);
 194 }
 195
 196 static int cpuusage_write(struct cgroup_subsys_state *css, struct cftype *cft,
 197                           u64 val)
 198 {
 199         struct cpuacct *ca = css_ca(css);
 200         int cpu;
 201
 202         /*
 203          * Only allow '0' here to do a reset.
 204          */
 205         if (val)
 206                 return -EINVAL;
 207
 208         for_each_possible_cpu(cpu)
 209                 cpuacct_cpuusage_write(ca, cpu, 0);
 210
 211         return 0;
 212 }
 213
 214 static int __cpuacct_percpu_seq_show(struct seq_file *m,
 215                                      enum cpuacct_stat_index index)
 216 {
 217         struct cpuacct *ca = css_ca(seq_css(m));
 218         u64 percpu;
 219         int i;
 220
 221         for_each_possible_cpu(i) {
 222                 percpu = cpuacct_cpuusage_read(ca, i, index);
 223                 seq_printf(m, "%llu ", (unsigned long long) percpu);
 224         }
 225         seq_printf(m, "\n");
 226         return 0;
 227 }
 228
 229 static int cpuacct_percpu_user_seq_show(struct seq_file *m, void *V)
 230 {
 231         return __cpuacct_percpu_seq_show(m, CPUACCT_STAT_USER);
 232 }
 233
 234 static int cpuacct_percpu_sys_seq_show(struct seq_file *m, void *V)
 235 {
 236         return __cpuacct_percpu_seq_show(m, CPUACCT_STAT_SYSTEM);
 237 }
 238
 239 static int cpuacct_percpu_seq_show(struct seq_file *m, void *V)
 240 {
 241         return __cpuacct_percpu_seq_show(m, CPUACCT_STAT_NSTATS);
 242 }
 243
 244 static int cpuacct_all_seq_show(struct seq_file *m, void *V)
 245 {
 246         struct cpuacct *ca = css_ca(seq_css(m));
 247         int index;
 248         int cpu;
 249
 250         seq_puts(m, "cpu");
 251         for (index = 0; index < CPUACCT_STAT_NSTATS; index++)
 252                 seq_printf(m, " %s", cpuacct_stat_desc[index]);
 253         seq_puts(m, "\n");
 254
 255         for_each_possible_cpu(cpu) {
 256                 struct cpuacct_usage *cpuusage = per_cpu_ptr(ca->cpuusage, cpu);
 257
 258                 seq_printf(m, "%d", cpu);
 259
 260                 for (index = 0; index < CPUACCT_STAT_NSTATS; index++) {
 261 #ifndef CONFIG_64BIT
 262                         /*
 263                          * Take rq->lock to make 64-bit read safe on 32-bit
 264                          * platforms.
 265                          */
 266                         raw_spin_lock_irq(&cpu_rq(cpu)->lock);
 267 #endif
 268
 269                         seq_printf(m, " %llu", cpuusage->usages[index]);
 270
 271 #ifndef CONFIG_64BIT
 272                         raw_spin_unlock_irq(&cpu_rq(cpu)->lock);
 273 #endif
 274                 }
 275                 seq_puts(m, "\n");
 276         }
 277         return 0;
 278 }
 279
 280 static int cpuacct_stats_show(struct seq_file *sf, void *v)
 281 {
 282         struct cpuacct *ca = css_ca(seq_css(sf));
 283         s64 val[CPUACCT_STAT_NSTATS];
 284         int cpu;
 285         int stat;
 286
 287         memset(val, 0, sizeof(val));
 288         for_each_possible_cpu(cpu) {
 289                 u64 *cpustat = per_cpu_ptr(ca->cpustat, cpu)->cpustat;
 290
 291                 val[CPUACCT_STAT_USER]   += cpustat[CPUTIME_USER];
 292                 val[CPUACCT_STAT_USER]   += cpustat[CPUTIME_NICE];
 293                 val[CPUACCT_STAT_SYSTEM] += cpustat[CPUTIME_SYSTEM];
 294                 val[CPUACCT_STAT_SYSTEM] += cpustat[CPUTIME_IRQ];
 295                 val[CPUACCT_STAT_SYSTEM] += cpustat[CPUTIME_SOFTIRQ];
 296         }
 297
 298         for (stat = 0; stat < CPUACCT_STAT_NSTATS; stat++) {
 299                 seq_printf(sf, "%s %lld\n",
 300                            cpuacct_stat_desc[stat],
 301                            (long long)nsec_to_clock_t(val[stat]));
 302         }
 303
 304         return 0;
 305 }
 306
 307 static struct cftype files[] = {
 308         {
 309                 .name = "usage",
 310                 .read_u64 = cpuusage_read,
 311                 .write_u64 = cpuusage_write,
 312         },
 313         {
 314                 .name = "usage_user",
 315                 .read_u64 = cpuusage_user_read,
 316         },
 317         {
 318                 .name = "usage_sys",
 319                 .read_u64 = cpuusage_sys_read,
 320         },
 321         {
 322                 .name = "usage_percpu",
 323                 .seq_show = cpuacct_percpu_seq_show,
 324         },
 325         {
 326                 .name = "usage_percpu_user",
 327                 .seq_show = cpuacct_percpu_user_seq_show,
 328         },
 329         {
 330                 .name = "usage_percpu_sys",
 331                 .seq_show = cpuacct_percpu_sys_seq_show,
 332         },
 333         {
 334                 .name = "usage_all",
 335                 .seq_show = cpuacct_all_seq_show,
 336         },
 337         {
 338                 .name = "stat",
 339                 .seq_show = cpuacct_stats_show,
 340         },
 341         { }     /* terminate */
 342 };
 343
 344 /*
 345  * charge this task's execution time to its accounting group.
 346  *
 347  * called with rq->lock held.
 348  */
 349 void cpuacct_charge(struct task_struct *tsk, u64 cputime)
 350 {
 351         struct cpuacct *ca;
 352         int index = CPUACCT_STAT_SYSTEM;
 353         struct pt_regs *regs = task_pt_regs(tsk);
 354
 355         if (regs && user_mode(regs))
 356                 index = CPUACCT_STAT_USER;
 357
 358         rcu_read_lock();
 359
 360         for (ca = task_ca(tsk); ca; ca = parent_ca(ca))
 361                 this_cpu_ptr(ca->cpuusage)->usages[index] += cputime;
 362
 363         rcu_read_unlock();
 364 }
 365
 366 /*
 367  * Add user/system time to cpuacct.
 368  *
 369  * Note: it's the caller that updates the account of the root cgroup.
 370  */
 371 void cpuacct_account_field(struct task_struct *tsk, int index, u64 val)
 372 {
 373         struct cpuacct *ca;
 374
 375         rcu_read_lock();
 376         for (ca = task_ca(tsk); ca != &root_cpuacct; ca = parent_ca(ca))
 377                 this_cpu_ptr(ca->cpustat)->cpustat[index] += val;
 378         rcu_read_unlock();
 379 }
 380
 381 struct cgroup_subsys cpuacct_cgrp_subsys = {
 382         .css_alloc      = cpuacct_css_alloc,
 383         .css_free       = cpuacct_css_free,
 384         .legacy_cftypes = files,
 385         .early_init     = true,
 386 };