Messages in this thread Patch in this message | | | Date | Sat, 06 Mar 2021 11:42:25 -0000 | From | "tip-bot2 for Peter Zijlstra" <> | Subject | [tip: sched/core] sched: Optimize migration_cpu_stop() |
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The following commit has been merged into the sched/core branch of tip:
Commit-ID: 3f1bc119cd7fc987c8ed25ffb717f99403bb308c Gitweb: https://git.kernel.org/tip/3f1bc119cd7fc987c8ed25ffb717f99403bb308c Author: Peter Zijlstra <peterz@infradead.org> AuthorDate: Wed, 24 Feb 2021 11:21:35 +01:00 Committer: Ingo Molnar <mingo@kernel.org> CommitterDate: Sat, 06 Mar 2021 12:40:21 +01:00
sched: Optimize migration_cpu_stop()
When the purpose of migration_cpu_stop() is to migrate the task to 'any' valid CPU, don't migrate the task when it's already running on a valid CPU.
Fixes: 6d337eab041d ("sched: Fix migrate_disable() vs set_cpus_allowed_ptr()") Cc: stable@kernel.org Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Reviewed-by: Valentin Schneider <valentin.schneider@arm.com> Link: https://lkml.kernel.org/r/20210224131355.569238629@infradead.org --- kernel/sched/core.c | 13 ++++++++++++- 1 file changed, 12 insertions(+), 1 deletion(-)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 84b657f..ac05afb 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -1936,14 +1936,25 @@ static int migration_cpu_stop(void *data) complete = true; } - if (dest_cpu < 0) + if (dest_cpu < 0) { + if (cpumask_test_cpu(task_cpu(p), &p->cpus_mask)) + goto out; + dest_cpu = cpumask_any_distribute(&p->cpus_mask); + } if (task_on_rq_queued(p)) rq = __migrate_task(rq, &rf, p, dest_cpu); else p->wake_cpu = dest_cpu; + /* + * XXX __migrate_task() can fail, at which point we might end + * up running on a dodgy CPU, AFAICT this can only happen + * during CPU hotplug, at which point we'll get pushed out + * anyway, so it's probably not a big deal. + */ + } else if (pending) { /* * This happens when we get migrated between migrate_enable()'s
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