1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * /proc/schedstat implementation
4 */
5 #include "sched.h"
6
__update_stats_wait_start(struct rq * rq,struct task_struct * p,struct sched_statistics * stats)7 void __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
__update_stats_wait_end(struct rq * rq,struct task_struct * p,struct sched_statistics * stats)21 void __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
__update_stats_enqueue_sleeper(struct rq * rq,struct task_struct * p,struct sched_statistics * stats)48 void __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 /*
97 * Blocking time is in units of nanosecs, so shift by
98 * 20 to get a milliseconds-range estimation of the
99 * amount of time that the task spent sleeping:
100 */
101 if (unlikely(prof_on == SLEEP_PROFILING)) {
102 profile_hits(SLEEP_PROFILING,
103 (void *)get_wchan(p),
104 delta >> 20);
105 }
106 account_scheduler_latency(p, delta >> 10, 0);
107 }
108 }
109 }
110
111 /*
112 * Current schedstat API version.
113 *
114 * Bump this up when changing the output format or the meaning of an existing
115 * format, so that tools can adapt (or abort)
116 */
117 #define SCHEDSTAT_VERSION 15
118
show_schedstat(struct seq_file * seq,void * v)119 static int show_schedstat(struct seq_file *seq, void *v)
120 {
121 int cpu;
122
123 if (v == (void *)1) {
124 seq_printf(seq, "version %d\n", SCHEDSTAT_VERSION);
125 seq_printf(seq, "timestamp %lu\n", jiffies);
126 } else {
127 struct rq *rq;
128 #ifdef CONFIG_SMP
129 struct sched_domain *sd;
130 int dcount = 0;
131 #endif
132 cpu = (unsigned long)(v - 2);
133 rq = cpu_rq(cpu);
134
135 /* runqueue-specific stats */
136 seq_printf(seq,
137 "cpu%d %u 0 %u %u %u %u %llu %llu %lu",
138 cpu, rq->yld_count,
139 rq->sched_count, rq->sched_goidle,
140 rq->ttwu_count, rq->ttwu_local,
141 rq->rq_cpu_time,
142 rq->rq_sched_info.run_delay, rq->rq_sched_info.pcount);
143
144 seq_printf(seq, "\n");
145
146 #ifdef CONFIG_SMP
147 /* domain-specific stats */
148 rcu_read_lock();
149 for_each_domain(cpu, sd) {
150 enum cpu_idle_type itype;
151
152 seq_printf(seq, "domain%d %*pb", dcount++,
153 cpumask_pr_args(sched_domain_span(sd)));
154 for (itype = CPU_IDLE; itype < CPU_MAX_IDLE_TYPES;
155 itype++) {
156 seq_printf(seq, " %u %u %u %u %u %u %u %u",
157 sd->lb_count[itype],
158 sd->lb_balanced[itype],
159 sd->lb_failed[itype],
160 sd->lb_imbalance[itype],
161 sd->lb_gained[itype],
162 sd->lb_hot_gained[itype],
163 sd->lb_nobusyq[itype],
164 sd->lb_nobusyg[itype]);
165 }
166 seq_printf(seq,
167 " %u %u %u %u %u %u %u %u %u %u %u %u\n",
168 sd->alb_count, sd->alb_failed, sd->alb_pushed,
169 sd->sbe_count, sd->sbe_balanced, sd->sbe_pushed,
170 sd->sbf_count, sd->sbf_balanced, sd->sbf_pushed,
171 sd->ttwu_wake_remote, sd->ttwu_move_affine,
172 sd->ttwu_move_balance);
173 }
174 rcu_read_unlock();
175 #endif
176 }
177 return 0;
178 }
179
180 /*
181 * This iterator needs some explanation.
182 * It returns 1 for the header position.
183 * This means 2 is cpu 0.
184 * In a hotplugged system some CPUs, including cpu 0, may be missing so we have
185 * to use cpumask_* to iterate over the CPUs.
186 */
schedstat_start(struct seq_file * file,loff_t * offset)187 static void *schedstat_start(struct seq_file *file, loff_t *offset)
188 {
189 unsigned long n = *offset;
190
191 if (n == 0)
192 return (void *) 1;
193
194 n--;
195
196 if (n > 0)
197 n = cpumask_next(n - 1, cpu_online_mask);
198 else
199 n = cpumask_first(cpu_online_mask);
200
201 *offset = n + 1;
202
203 if (n < nr_cpu_ids)
204 return (void *)(unsigned long)(n + 2);
205
206 return NULL;
207 }
208
schedstat_next(struct seq_file * file,void * data,loff_t * offset)209 static void *schedstat_next(struct seq_file *file, void *data, loff_t *offset)
210 {
211 (*offset)++;
212
213 return schedstat_start(file, offset);
214 }
215
schedstat_stop(struct seq_file * file,void * data)216 static void schedstat_stop(struct seq_file *file, void *data)
217 {
218 }
219
220 static const struct seq_operations schedstat_sops = {
221 .start = schedstat_start,
222 .next = schedstat_next,
223 .stop = schedstat_stop,
224 .show = show_schedstat,
225 };
226
proc_schedstat_init(void)227 static int __init proc_schedstat_init(void)
228 {
229 proc_create_seq("schedstat", 0, NULL, &schedstat_sops);
230 return 0;
231 }
232 subsys_initcall(proc_schedstat_init);
233