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| author | Frederic Weisbecker <frederic@kernel.org> | 2019-12-03 17:01:05 +0100 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2019-12-17 13:32:50 +0100 |
| commit | 7c2e8bbd87db661122e92d71a394dd7bb3ada4d3 (patch) | |
| tree | 66f0e3c1973d82305b2456a716559ce5746ad31c | |
| parent | 025f50f3866486a5278afa91f0d3b6b780141050 (diff) | |
| download | linux-7c2e8bbd87db661122e92d71a394dd7bb3ada4d3.tar.bz2 | |
sched: Spare resched IPI when prio changes on a single fair task
The runqueue of a fair task being remotely reniced is going to get a
resched IPI in order to reassess which task should be the current
running on the CPU. However that evaluation is useless if the fair task
is running alone, in which case we can spare that IPI, preventing
nohz_full CPUs from being disturbed.
Reported-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Link: https://lkml.kernel.org/r/20191203160106.18806-2-frederic@kernel.org
| -rw-r--r-- | kernel/sched/fair.c | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 08a233e97a01..846f50bd0c0b 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -10322,6 +10322,9 @@ prio_changed_fair(struct rq *rq, struct task_struct *p, int oldprio) if (!task_on_rq_queued(p)) return; + if (rq->cfs.nr_running == 1) + return; + /* * Reschedule if we are currently running on this runqueue and * our priority decreased, or if we are not currently running on |