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                         account_scheduler_latency(p, delta >> 10, 0);
  96                 }
  97         }
  98 }
  99
 100 /*
 101  * Current schedstat API version.
 102  *
 103  * Bump this up when changing the output format or the meaning of an existing
 104  * format, so that tools can adapt (or abort)
 105  */
 106 #define SCHEDSTAT_VERSION 16
 107
 108 static int show_schedstat(struct seq_file *seq, void *v)
 109 {
 110         int cpu;
 111
 112         if (v == (void *)1) {
 113                 seq_printf(seq, "version %d\n", SCHEDSTAT_VERSION);
 114                 seq_printf(seq, "timestamp %lu\n", jiffies);
 115         } else {
 116                 struct rq *rq;
 117 #ifdef CONFIG_SMP
 118                 struct sched_domain *sd;
 119                 int dcount = 0;
 120 #endif
 121                 cpu = (unsigned long)(v - 2);
 122                 rq = cpu_rq(cpu);
 123
 124                 /* runqueue-specific stats */
 125                 seq_printf(seq,
 126                     "cpu%d %u 0 %u %u %u %u %llu %llu %lu",
 127                     cpu, rq->yld_count,
 128                     rq->sched_count, rq->sched_goidle,
 129                     rq->ttwu_count, rq->ttwu_local,
 130                     rq->rq_cpu_time,
 131                     rq->rq_sched_info.run_delay, rq->rq_sched_info.pcount);
 132
 133                 seq_printf(seq, "\n");
 134
 135 #ifdef CONFIG_SMP
 136                 /* domain-specific stats */
 137                 rcu_read_lock();
 138                 for_each_domain(cpu, sd) {
 139                         enum cpu_idle_type itype;
 140
 141                         seq_printf(seq, "domain%d %*pb", dcount++,
 142                                    cpumask_pr_args(sched_domain_span(sd)));
 143                         for (itype = 0; itype < CPU_MAX_IDLE_TYPES; itype++) {
 144                                 seq_printf(seq, " %u %u %u %u %u %u %u %u",
 145                                     sd->lb_count[itype],
 146                                     sd->lb_balanced[itype],
 147                                     sd->lb_failed[itype],
 148                                     sd->lb_imbalance[itype],
 149                                     sd->lb_gained[itype],
 150                                     sd->lb_hot_gained[itype],
 151                                     sd->lb_nobusyq[itype],
 152                                     sd->lb_nobusyg[itype]);
 153                         }
 154                         seq_printf(seq,
 155                                    " %u %u %u %u %u %u %u %u %u %u %u %u\n",
 156                             sd->alb_count, sd->alb_failed, sd->alb_pushed,
 157                             sd->sbe_count, sd->sbe_balanced, sd->sbe_pushed,
 158                             sd->sbf_count, sd->sbf_balanced, sd->sbf_pushed,
 159                             sd->ttwu_wake_remote, sd->ttwu_move_affine,
 160                             sd->ttwu_move_balance);
 161                 }
 162                 rcu_read_unlock();
 163 #endif
 164         }
 165         return 0;
 166 }
 167
 168 /*
 169  * This iterator needs some explanation.
 170  * It returns 1 for the header position.
 171  * This means 2 is cpu 0.
 172  * In a hotplugged system some CPUs, including cpu 0, may be missing so we have
 173  * to use cpumask_* to iterate over the CPUs.
 174  */
 175 static void *schedstat_start(struct seq_file *file, loff_t *offset)
 176 {
 177         unsigned long n = *offset;
 178
 179         if (n == 0)
 180                 return (void *) 1;
 181
 182         n--;
 183
 184         if (n > 0)
 185                 n = cpumask_next(n - 1, cpu_online_mask);
 186         else
 187                 n = cpumask_first(cpu_online_mask);
 188
 189         *offset = n + 1;
 190
 191         if (n < nr_cpu_ids)
 192                 return (void *)(unsigned long)(n + 2);
 193
 194         return NULL;
 195 }
 196
 197 static void *schedstat_next(struct seq_file *file, void *data, loff_t *offset)
 198 {
 199         (*offset)++;
 200
 201         return schedstat_start(file, offset);
 202 }
 203
 204 static void schedstat_stop(struct seq_file *file, void *data)
 205 {
 206 }
 207
 208 static const struct seq_operations schedstat_sops = {
 209         .start = schedstat_start,
 210         .next  = schedstat_next,
 211         .stop  = schedstat_stop,
 212         .show  = show_schedstat,
 213 };
 214
 215 static int __init proc_schedstat_init(void)
 216 {
 217         proc_create_seq("schedstat", 0, NULL, &schedstat_sops);
 218         return 0;
 219 }
 220 subsys_initcall(proc_schedstat_init);