stats.c

  1// SPDX-License-Identifier: GPL-2.0
  2/*
  3 * /proc/schedstat implementation
  4 */
  5#include "sched.h"
  6
  7void __update_stats_wait_start(struct rq *rq, struct task_struct *p,
  8			       struct sched_statistics *stats)
  9{
 10	u64 wait_start, prev_wait_start;
 11
 12	wait_start = rq_clock(rq);
 13	prev_wait_start = schedstat_val(stats->wait_start);
 14
 15	if (p && likely(wait_start > prev_wait_start))
 16		wait_start -= prev_wait_start;
 17
 18	__schedstat_set(stats->wait_start, wait_start);
 19}
 20
 21void __update_stats_wait_end(struct rq *rq, struct task_struct *p,
 22			     struct sched_statistics *stats)
 23{
 24	u64 delta = rq_clock(rq) - schedstat_val(stats->wait_start);
 25
 26	if (p) {
 27		if (task_on_rq_migrating(p)) {
 28			/*
 29			 * Preserve migrating task's wait time so wait_start
 30			 * time stamp can be adjusted to accumulate wait time
 31			 * prior to migration.
 32			 */
 33			__schedstat_set(stats->wait_start, delta);
 34
 35			return;
 36		}
 37
 38		trace_sched_stat_wait(p, delta);
 39	}
 40
 41	__schedstat_set(stats->wait_max,
 42			max(schedstat_val(stats->wait_max), delta));
 43	__schedstat_inc(stats->wait_count);
 44	__schedstat_add(stats->wait_sum, delta);
 45	__schedstat_set(stats->wait_start, 0);
 46}
 47
 48void __update_stats_enqueue_sleeper(struct rq *rq, struct task_struct *p,
 49				    struct sched_statistics *stats)
 50{
 51	u64 sleep_start, block_start;
 52
 53	sleep_start = schedstat_val(stats->sleep_start);
 54	block_start = schedstat_val(stats->block_start);
 55
 56	if (sleep_start) {
 57		u64 delta = rq_clock(rq) - sleep_start;
 58
 59		if ((s64)delta < 0)
 60			delta = 0;
 61
 62		if (unlikely(delta > schedstat_val(stats->sleep_max)))
 63			__schedstat_set(stats->sleep_max, delta);
 64
 65		__schedstat_set(stats->sleep_start, 0);
 66		__schedstat_add(stats->sum_sleep_runtime, delta);
 67
 68		if (p) {
 69			account_scheduler_latency(p, delta >> 10, 1);
 70			trace_sched_stat_sleep(p, delta);
 71		}
 72	}
 73
 74	if (block_start) {
 75		u64 delta = rq_clock(rq) - block_start;
 76
 77		if ((s64)delta < 0)
 78			delta = 0;
 79
 80		if (unlikely(delta > schedstat_val(stats->block_max)))
 81			__schedstat_set(stats->block_max, delta);
 82
 83		__schedstat_set(stats->block_start, 0);
 84		__schedstat_add(stats->sum_sleep_runtime, delta);
 85		__schedstat_add(stats->sum_block_runtime, delta);
 86
 87		if (p) {
 88			if (p->in_iowait) {
 89				__schedstat_add(stats->iowait_sum, delta);
 90				__schedstat_inc(stats->iowait_count);
 91				trace_sched_stat_iowait(p, delta);
 92			}
 93
 94			trace_sched_stat_blocked(p, delta);
 95
 96			account_scheduler_latency(p, delta >> 10, 0);
 97		}
 98	}
 99}
100
101/*
102 * Current schedstat API version.
103 *
104 * Bump this up when changing the output format or the meaning of an existing
105 * format, so that tools can adapt (or abort)
106 */
107#define SCHEDSTAT_VERSION 17
108
109static int show_schedstat(struct seq_file *seq, void *v)
110{
111	int cpu;
112
113	if (v == (void *)1) {
114		seq_printf(seq, "version %d\n", SCHEDSTAT_VERSION);
115		seq_printf(seq, "timestamp %lu\n", jiffies);
116	} else {
117		struct rq *rq;
118		struct sched_domain *sd;
119		int dcount = 0;
120		cpu = (unsigned long)(v - 2);
121		rq = cpu_rq(cpu);
122
123		/* runqueue-specific stats */
124		seq_printf(seq,
125		    "cpu%d %u 0 %u %u %u %u %llu %llu %lu",
126		    cpu, rq->yld_count,
127		    rq->sched_count, rq->sched_goidle,
128		    rq->ttwu_count, rq->ttwu_local,
129		    rq->rq_cpu_time,
130		    rq->rq_sched_info.run_delay, rq->rq_sched_info.pcount);
131
132		seq_printf(seq, "\n");
133
134		/* domain-specific stats */
135		rcu_read_lock();
136		for_each_domain(cpu, sd) {
137			enum cpu_idle_type itype;
138
139			seq_printf(seq, "domain%d %s %*pb", dcount++, sd->name,
140				   cpumask_pr_args(sched_domain_span(sd)));
141			for (itype = 0; itype < CPU_MAX_IDLE_TYPES; itype++) {
142				seq_printf(seq, " %u %u %u %u %u %u %u %u %u %u %u",
143				    sd->lb_count[itype],
144				    sd->lb_balanced[itype],
145				    sd->lb_failed[itype],
146				    sd->lb_imbalance_load[itype],
147				    sd->lb_imbalance_util[itype],
148				    sd->lb_imbalance_task[itype],
149				    sd->lb_imbalance_misfit[itype],
150				    sd->lb_gained[itype],
151				    sd->lb_hot_gained[itype],
152				    sd->lb_nobusyq[itype],
153				    sd->lb_nobusyg[itype]);
154			}
155			seq_printf(seq,
156				   " %u %u %u %u %u %u %u %u %u %u %u %u\n",
157			    sd->alb_count, sd->alb_failed, sd->alb_pushed,
158			    sd->sbe_count, sd->sbe_balanced, sd->sbe_pushed,
159			    sd->sbf_count, sd->sbf_balanced, sd->sbf_pushed,
160			    sd->ttwu_wake_remote, sd->ttwu_move_affine,
161			    sd->ttwu_move_balance);
162		}
163		rcu_read_unlock();
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 */
175static 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
197static void *schedstat_next(struct seq_file *file, void *data, loff_t *offset)
198{
199	(*offset)++;
200
201	return schedstat_start(file, offset);
202}
203
204static void schedstat_stop(struct seq_file *file, void *data)
205{
206}
207
208static const struct seq_operations schedstat_sops = {
209	.start = schedstat_start,
210	.next  = schedstat_next,
211	.stop  = schedstat_stop,
212	.show  = show_schedstat,
213};
214
215static int __init proc_schedstat_init(void)
216{
217	proc_create_seq("schedstat", 0, NULL, &schedstat_sops);
218	return 0;
219}
220subsys_initcall(proc_schedstat_init);