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| author |   Josh Don <joshdon@google.com> | 2021-08-19 18:04:02 -0700 |
|---|---|---|
| committer |   Peter Zijlstra <peterz@infradead.org> | 2021-10-05 15:51:37 +0200 |
| commit | 51ce83ed523b00d58f2937ec014b12daaad55185 (patch) | |
| tree | a1c3c6f96f30870a81917a4c85e4d53da60d3d2a /kernel/sched/debug.c | |
| parent | sched: Account number of SCHED_IDLE entities on each cfs_rq (diff) | |
| download | linux-dev-51ce83ed523b00d58f2937ec014b12daaad55185.tar.xz linux-dev-51ce83ed523b00d58f2937ec014b12daaad55185.zip | |
sched: reduce sched slice for SCHED_IDLE entities
Use a small, non-scaled min granularity for SCHED_IDLE entities, when
competing with normal entities. This reduces the latency of getting
a normal entity back on cpu, at the expense of increased context
switch frequency of SCHED_IDLE entities.
The benefit of this change is to reduce the round-robin latency for
normal entities when competing with a SCHED_IDLE entity.
Example: on a machine with HZ=1000, spawned two threads, one of which is
SCHED_IDLE, and affined to one cpu. Without this patch, the SCHED_IDLE
thread runs for 4ms then waits for 1.4s. With this patch, it runs for
1ms and waits 340ms (as it round-robins with the other thread).
Signed-off-by: Josh Don <joshdon@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lore.kernel.org/r/20210820010403.946838-4-joshdon@google.com
Diffstat (limited to '')
| -rw-r--r-- | kernel/sched/debug.c | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/kernel/sched/debug.c b/kernel/sched/debug.c index 2e5fdd98dacc..34913a7f775a 100644 --- a/kernel/sched/debug.c +++ b/kernel/sched/debug.c @@ -311,6 +311,7 @@ static __init int sched_init_debug(void) debugfs_create_u32("latency_ns", 0644, debugfs_sched, &sysctl_sched_latency); debugfs_create_u32("min_granularity_ns", 0644, debugfs_sched, &sysctl_sched_min_granularity); + debugfs_create_u32("idle_min_granularity_ns", 0644, debugfs_sched, &sysctl_sched_idle_min_granularity); debugfs_create_u32("wakeup_granularity_ns", 0644, debugfs_sched, &sysctl_sched_wakeup_granularity); debugfs_create_u32("latency_warn_ms", 0644, debugfs_sched, &sysctl_resched_latency_warn_ms); @@ -812,6 +813,7 @@ static void sched_debug_header(struct seq_file *m) SEQ_printf(m, " .%-40s: %Ld.%06ld\n", #x, SPLIT_NS(x)) PN(sysctl_sched_latency); PN(sysctl_sched_min_granularity); + PN(sysctl_sched_idle_min_granularity); PN(sysctl_sched_wakeup_granularity); P(sysctl_sched_child_runs_first); P(sysctl_sched_features); |