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| author |   Paul Turner <pjt@google.com> | 2021-04-16 14:29:36 -0700 |
|---|---|---|
| committer |   Peter Zijlstra <peterz@infradead.org> | 2021-04-21 13:55:41 +0200 |
| commit | c006fac556e401a62054d065da168099ea5a5b10 (patch) | |
| tree | d35910fa4eab4ab7821226ebc76709a04a33baf5 /include/linux/sched | |
| parent | sched/fair: Move update_nohz_stats() to the CONFIG_NO_HZ_COMMON block to simplify the code & fix an unused function warning (diff) | |
| download | linux-dev-c006fac556e401a62054d065da168099ea5a5b10.tar.xz linux-dev-c006fac556e401a62054d065da168099ea5a5b10.zip | |
sched: Warn on long periods of pending need_resched
CPU scheduler marks need_resched flag to signal a schedule() on a
particular CPU. But, schedule() may not happen immediately in cases
where the current task is executing in the kernel mode (no
preemption state) for extended periods of time.
This patch adds a warn_on if need_resched is pending for more than the
time specified in sysctl resched_latency_warn_ms. If it goes off, it is
likely that there is a missing cond_resched() somewhere. Monitoring is
done via the tick and the accuracy is hence limited to jiffy scale. This
also means that we won't trigger the warning if the tick is disabled.
This feature (LATENCY_WARN) is default disabled.
Signed-off-by: Paul Turner <pjt@google.com>
Signed-off-by: Josh Don <joshdon@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20210416212936.390566-1-joshdon@google.com
Diffstat (limited to 'include/linux/sched')
| -rw-r--r-- | include/linux/sched/sysctl.h | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/include/linux/sched/sysctl.h b/include/linux/sched/sysctl.h index 0a3f34638cf5..db2c0f34aaaf 100644 --- a/include/linux/sched/sysctl.h +++ b/include/linux/sched/sysctl.h @@ -48,6 +48,9 @@ extern unsigned int sysctl_numa_balancing_scan_size; #ifdef CONFIG_SCHED_DEBUG extern __read_mostly unsigned int sysctl_sched_migration_cost; extern __read_mostly unsigned int sysctl_sched_nr_migrate; + +extern int sysctl_resched_latency_warn_ms; +extern int sysctl_resched_latency_warn_once; #endif /* |