kernel/sched/stats.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * /proc/schedstat implementation
   4  */
   5
   6 void __update_stats_wait_start(struct rq *rq, struct task_struct *p,
   7                                struct sched_statistics *stats)
   8 {
   9         u64 wait_start, prev_wait_start;
  10
  11         wait_start = rq_clock(rq);
  12         prev_wait_start = schedstat_val(stats->wait_start);
  13
  14         if (p && likely(wait_start > prev_wait_start))
  15                 wait_start -= prev_wait_start;
  16
  17         __schedstat_set(stats->wait_start, wait_start);
  18 }
  19
  20 void __update_stats_wait_end(struct rq *rq, struct task_struct *p,
  21                              struct sched_statistics *stats)
  22 {
  23         u64 delta = rq_clock(rq) - schedstat_val(stats->wait_start);
  24
  25         if (p) {
  26                 if (task_on_rq_migrating(p)) {
  27                         /*
  28                          * Preserve migrating task's wait time so wait_start
  29                          * time stamp can be adjusted to accumulate wait time
  30                          * prior to migration.
  31                          */
  32                         __schedstat_set(stats->wait_start, delta);
  33
  34                         return;
  35                 }
  36
  37                 trace_sched_stat_wait(p, delta);
  38         }
  39
  40         __schedstat_set(stats->wait_max,
  41                         max(schedstat_val(stats->wait_max), delta));
  42         __schedstat_inc(stats->wait_count);
  43         __schedstat_add(stats->wait_sum, delta);
  44         __schedstat_set(stats->wait_start, 0);
  45 }
  46
  47 void __update_stats_enqueue_sleeper(struct rq *rq, struct task_struct *p,
  48                                     struct sched_statistics *stats)
  49 {
  50         u64 sleep_start, block_start;
  51
  52         sleep_start = schedstat_val(stats->sleep_start);
  53         block_start = schedstat_val(stats->block_start);
  54
  55         if (sleep_start) {
  56                 u64 delta = rq_clock(rq) - sleep_start;
  57
  58                 if ((s64)delta < 0)
  59                         delta = 0;
  60
  61                 if (unlikely(delta > schedstat_val(stats->sleep_max)))
  62                         __schedstat_set(stats->sleep_max, delta);
  63
  64                 __schedstat_set(stats->sleep_start, 0);
  65                 __schedstat_add(stats->sum_sleep_runtime, delta);
  66
  67                 if (p) {
  68                         account_scheduler_latency(p, delta >> 10, 1);
  69                         trace_sched_stat_sleep(p, delta);
  70                 }
  71         }
  72
  73         if (block_start) {
  74                 u64 delta = rq_clock(rq) - block_start;
  75
  76                 if ((s64)delta < 0)
  77                         delta = 0;
  78
  79                 if (unlikely(delta > schedstat_val(stats->block_max)))
  80                         __schedstat_set(stats->block_max, delta);
  81
  82                 __schedstat_set(stats->block_start, 0);
  83                 __schedstat_add(stats->sum_sleep_runtime, delta);
  84                 __schedstat_add(stats->sum_block_runtime, delta);
  85
  86                 if (p) {
  87                         if (p->in_iowait) {
  88                                 __schedstat_add(stats->iowait_sum, delta);
  89                                 __schedstat_inc(stats->iowait_count);
  90                                 trace_sched_stat_iowait(p, delta);
  91                         }
  92
  93                         trace_sched_stat_blocked(p, delta);
  94
  95                         /*
  96                          * Blocking time is in units of nanosecs, so shift by
  97                          * 20 to get a milliseconds-range estimation of the
  98                          * amount of time that the task spent sleeping:
  99                          */
 100                         if (unlikely(prof_on == SLEEP_PROFILING)) {
 101                                 profile_hits(SLEEP_PROFILING,
 102                                              (void *)get_wchan(p),
 103                                              delta >> 20);
 104                         }
 105                         account_scheduler_latency(p, delta >> 10, 0);
 106                 }
 107         }
 108 }
 109
 110 /*
 111  * Current schedstat API version.
 112  *
 113  * Bump this up when changing the output format or the meaning of an existing
 114  * format, so that tools can adapt (or abort)
 115  */
 116 #define SCHEDSTAT_VERSION 15
 117
 118 static int show_schedstat(struct seq_file *seq, void *v)
 119 {
 120         int cpu;
 121
 122         if (v == (void *)1) {
 123                 seq_printf(seq, "version %d\n", SCHEDSTAT_VERSION);
 124                 seq_printf(seq, "timestamp %lu\n", jiffies);
 125         } else {
 126                 struct rq *rq;
 127 #ifdef CONFIG_SMP
 128                 struct sched_domain *sd;
 129                 int dcount = 0;
 130 #endif
 131                 cpu = (unsigned long)(v - 2);
 132                 rq = cpu_rq(cpu);
 133
 134                 /* runqueue-specific stats */
 135                 seq_printf(seq,
 136                     "cpu%d %u 0 %u %u %u %u %llu %llu %lu",
 137                     cpu, rq->yld_count,
 138                     rq->sched_count, rq->sched_goidle,
 139                     rq->ttwu_count, rq->ttwu_local,
 140                     rq->rq_cpu_time,
 141                     rq->rq_sched_info.run_delay, rq->rq_sched_info.pcount);
 142
 143                 seq_printf(seq, "\n");
 144
 145 #ifdef CONFIG_SMP
 146                 /* domain-specific stats */
 147                 rcu_read_lock();
 148                 for_each_domain(cpu, sd) {
 149                         enum cpu_idle_type itype;
 150
 151                         seq_printf(seq, "domain%d %*pb", dcount++,
 152                                    cpumask_pr_args(sched_domain_span(sd)));
 153                         for (itype = CPU_IDLE; itype < CPU_MAX_IDLE_TYPES;
 154                                         itype++) {
 155                                 seq_printf(seq, " %u %u %u %u %u %u %u %u",
 156                                     sd->lb_count[itype],
 157                                     sd->lb_balanced[itype],
 158                                     sd->lb_failed[itype],
 159                                     sd->lb_imbalance[itype],
 160                                     sd->lb_gained[itype],
 161                                     sd->lb_hot_gained[itype],
 162                                     sd->lb_nobusyq[itype],
 163                                     sd->lb_nobusyg[itype]);
 164                         }
 165                         seq_printf(seq,
 166                                    " %u %u %u %u %u %u %u %u %u %u %u %u\n",
 167                             sd->alb_count, sd->alb_failed, sd->alb_pushed,
 168                             sd->sbe_count, sd->sbe_balanced, sd->sbe_pushed,
 169                             sd->sbf_count, sd->sbf_balanced, sd->sbf_pushed,
 170                             sd->ttwu_wake_remote, sd->ttwu_move_affine,
 171                             sd->ttwu_move_balance);
 172                 }
 173                 rcu_read_unlock();
 174 #endif
 175         }
 176         return 0;
 177 }
 178
 179 /*
 180  * This iterator needs some explanation.
 181  * It returns 1 for the header position.
 182  * This means 2 is cpu 0.
 183  * In a hotplugged system some CPUs, including cpu 0, may be missing so we have
 184  * to use cpumask_* to iterate over the CPUs.
 185  */
 186 static void *schedstat_start(struct seq_file *file, loff_t *offset)
 187 {
 188         unsigned long n = *offset;
 189
 190         if (n == 0)
 191                 return (void *) 1;
 192
 193         n--;
 194
 195         if (n > 0)
 196                 n = cpumask_next(n - 1, cpu_online_mask);
 197         else
 198                 n = cpumask_first(cpu_online_mask);
 199
 200         *offset = n + 1;
 201
 202         if (n < nr_cpu_ids)
 203                 return (void *)(unsigned long)(n + 2);
 204
 205         return NULL;
 206 }
 207
 208 static void *schedstat_next(struct seq_file *file, void *data, loff_t *offset)
 209 {
 210         (*offset)++;
 211
 212         return schedstat_start(file, offset);
 213 }
 214
 215 static void schedstat_stop(struct seq_file *file, void *data)
 216 {
 217 }
 218
 219 static const struct seq_operations schedstat_sops = {
 220         .start = schedstat_start,
 221         .next  = schedstat_next,
 222         .stop  = schedstat_stop,
 223         .show  = show_schedstat,
 224 };
 225
 226 static int __init proc_schedstat_init(void)
 227 {
 228         proc_create_seq("schedstat", 0, NULL, &schedstat_sops);
 229         return 0;
 230 }
 231 subsys_initcall(proc_schedstat_init);