kernel/sched/cpuacct.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * CPU accounting code for task groups.
   4  *
   5  * Based on the work by Paul Menage ([email protected]) and Balbir Singh
   6  * ([email protected]).
   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 ... */
  12 enum cpuacct_stat_index {
  13         CPUACCT_STAT_USER,      /* ... user mode */
  14         CPUACCT_STAT_SYSTEM,    /* ... kernel mode */
  15
  16         CPUACCT_STAT_NSTATS,
  17 };
  18
  19 static const char * const cpuacct_stat_desc[] = {
  20         [CPUACCT_STAT_USER] = "user",
  21         [CPUACCT_STAT_SYSTEM] = "system",
  22 };
  23
  24 struct cpuacct_usage {
  25         u64     usages[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         struct cpuacct_usage __percpu   *cpuusage;
  33         struct kernel_cpustat __percpu  *cpustat;
  34 };
  35
  36 static 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 */
  42 static inline struct cpuacct *task_ca(struct task_struct *tsk)
  43 {
  44         return css_ca(task_css(tsk, cpuacct_cgrp_id));
  45 }
  46
  47 static inline struct cpuacct *parent_ca(struct cpuacct *ca)
  48 {
  49         return css_ca(ca->css.parent);
  50 }
  51
  52 static DEFINE_PER_CPU(struct cpuacct_usage, root_cpuacct_cpuusage);
  53 static struct cpuacct root_cpuacct = {
  54         .cpustat        = &kernel_cpustat,
  55         .cpuusage       = &root_cpuacct_cpuusage,
  56 };
  57
  58 /* Create a new CPU accounting group */
  59 static struct cgroup_subsys_state *
  60 cpuacct_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
  81 out_free_cpuusage:
  82         free_percpu(ca->cpuusage);
  83 out_free_ca:
  84         kfree(ca);
  85 out:
  86         return ERR_PTR(-ENOMEM);
  87 }
  88
  89 /* Destroy an existing CPU accounting group */
  90 static 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
  99 static 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 suages.
 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_lock_irq(&cpu_rq(cpu)->lock);
 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_unlock_irq(&cpu_rq(cpu)->lock);
 130 #endif
 131
 132         return data;
 133 }
 134
 135 static 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_lock_irq(&cpu_rq(cpu)->lock);
 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_unlock_irq(&cpu_rq(cpu)->lock);
 152 #endif
 153 }
 154
 155 /* Return total CPU usage (in nanoseconds) of a group */
 156 static 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
 169 static u64 cpuusage_user_read(struct cgroup_subsys_state *css,
 170                               struct cftype *cft)
 171 {
 172         return __cpuusage_read(css, CPUACCT_STAT_USER);
 173 }
 174
 175 static u64 cpuusage_sys_read(struct cgroup_subsys_state *css,
 176                              struct cftype *cft)
 177 {
 178         return __cpuusage_read(css, CPUACCT_STAT_SYSTEM);
 179 }
 180
 181 static u64 cpuusage_read(struct cgroup_subsys_state *css, struct cftype *cft)
 182 {
 183         return __cpuusage_read(css, CPUACCT_STAT_NSTATS);
 184 }
 185
 186 static 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
 204 static 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
 219 static 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
 224 static 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
 229 static int cpuacct_percpu_seq_show(struct seq_file *m, void *V)
 230 {
 231         return __cpuacct_percpu_seq_show(m, CPUACCT_STAT_NSTATS);
 232 }
 233
 234 static 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_lock_irq(&cpu_rq(cpu)->lock);
 257 #endif
 258
 259                         seq_printf(m, " %llu", cpuusage->usages[index]);
 260
 261 #ifndef CONFIG_64BIT
 262                         raw_spin_unlock_irq(&cpu_rq(cpu)->lock);
 263 #endif
 264                 }
 265                 seq_puts(m, "\n");
 266         }
 267         return 0;
 268 }
 269
 270 static 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
 297 static 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  */
 339 void 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  */
 361 void 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
 371 struct 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 };