kernel/sched/cpuacct.c

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