diff options
| -rw-r--r-- | Documentation/scheduler/sched-stats.txt | 9 | ||||
| -rw-r--r-- | include/linux/sched/sysctl.h | 5 | ||||
| -rw-r--r-- | kernel/sched/fair.c | 26 | ||||
| -rw-r--r-- | kernel/sysctl.c | 16 |
4 files changed, 56 insertions, 0 deletions
diff --git a/Documentation/scheduler/sched-stats.txt b/Documentation/scheduler/sched-stats.txt index 8259b34a66ae..30635c5ac2f5 100644 --- a/Documentation/scheduler/sched-stats.txt +++ b/Documentation/scheduler/sched-stats.txt @@ -147,6 +147,15 @@ this file correlating for that process to: 2) time spent waiting on a runqueue 3) # of timeslices run on this cpu +/proc/sys/kernel/{sched_latency_warn_threshold_us,sched_latency_panic_threshold_us} +---------------- +schedstats provides procfs nodes /proc/sys/kernel/sched_latency_warn_threshold_us +and /proc/sys/kernel/sched_latency_panic_threshold_us. These can be configured +to detect unreasonably high scheduling latency. +Set sched_latency_warn_threshold_us or sched_latency_panic_threshold_us with +non-zero threshold to warn or panic system when scheduling latency higher than +configured threshold is detected. Default is 0 (disabled) for both. + A program could be easily written to make use of these extra fields to report on how well a particular process or set of processes is faring under the scheduler's policies. A simple version of such a program is diff --git a/include/linux/sched/sysctl.h b/include/linux/sched/sysctl.h index ce23dcd70b98..fdb75cab5243 100644 --- a/include/linux/sched/sysctl.h +++ b/include/linux/sched/sysctl.h @@ -129,6 +129,11 @@ extern unsigned int sysctl_sched_cfs_bandwidth_slice; extern unsigned int sysctl_sched_autogroup_enabled; #endif +#ifdef CONFIG_SCHEDSTATS +extern unsigned int sysctl_sched_latency_panic_threshold; +extern unsigned int sysctl_sched_latency_warn_threshold; +#endif + extern int sched_rr_timeslice; extern int sched_rr_handler(struct ctl_table *table, int write, diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 98740228ed32..1da6091b54f3 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -30,6 +30,7 @@ #include <linux/mempolicy.h> #include <linux/migrate.h> #include <linux/task_work.h> +#include <linux/ratelimit.h> #include <trace/events/sched.h> @@ -122,6 +123,11 @@ unsigned int __read_mostly sysctl_sched_shares_window = 10000000UL; unsigned int sysctl_sched_cfs_bandwidth_slice = 5000UL; #endif +#ifdef CONFIG_SCHEDSTATS +unsigned int sysctl_sched_latency_panic_threshold; +unsigned int sysctl_sched_latency_warn_threshold; +#endif /* CONFIG_SCHEDSTATS */ + static inline void update_load_add(struct load_weight *lw, unsigned long inc) { lw->weight += inc; @@ -750,6 +756,25 @@ static void update_curr_fair(struct rq *rq) } #ifdef CONFIG_SCHEDSTATS +static inline void check_for_high_latency(struct task_struct *p, u64 latency_us) +{ + int do_warn, do_panic; + const char *fmt = "excessive latency comm=%s pid=%d latency=%llu(us)\n"; + static DEFINE_RATELIMIT_STATE(rs, DEFAULT_RATELIMIT_INTERVAL, + DEFAULT_RATELIMIT_BURST); + + do_warn = (sysctl_sched_latency_warn_threshold && + latency_us > sysctl_sched_latency_warn_threshold); + do_panic = (sysctl_sched_latency_panic_threshold && + latency_us > sysctl_sched_latency_panic_threshold); + if (unlikely(do_panic || (do_warn && __ratelimit(&rs)))) { + if (do_panic) + panic(fmt, p->comm, p->pid, latency_us); + else + printk_deferred(fmt, p->comm, p->pid, latency_us); + } +} + static inline void update_stats_wait_start(struct cfs_rq *cfs_rq, struct sched_entity *se) { @@ -780,6 +805,7 @@ update_stats_wait_end(struct cfs_rq *cfs_rq, struct sched_entity *se) return; } trace_sched_stat_wait(p, delta); + check_for_high_latency(p, delta >> 10); } se->statistics.wait_max = max(se->statistics.wait_max, delta); diff --git a/kernel/sysctl.c b/kernel/sysctl.c index 16e465103020..188c7fabeec0 100644 --- a/kernel/sysctl.c +++ b/kernel/sysctl.c @@ -593,6 +593,22 @@ static struct ctl_table kern_table[] = { .extra1 = &one, }, #endif +#ifdef CONFIG_SCHEDSTATS + { + .procname = "sched_latency_panic_threshold_us", + .data = &sysctl_sched_latency_panic_threshold, + .maxlen = sizeof(unsigned int), + .mode = 0644, + .proc_handler = proc_dointvec_minmax, + }, + { + .procname = "sched_latency_warn_threshold_us", + .data = &sysctl_sched_latency_warn_threshold, + .maxlen = sizeof(unsigned int), + .mode = 0644, + .proc_handler = proc_dointvec_minmax, + }, +#endif #ifdef CONFIG_PROVE_LOCKING { .procname = "prove_locking", |