sched: Optimize finish_lock_switch()

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The kernel test robot measured a -1.6% performance regression on
will-it-scale/sched_yield due to commit:

  2558aacff8 ("sched/hotplug: Ensure only per-cpu kthreads run during hotplug")

Even though we were careful to replace a single load with another
single load from the same cacheline.

Restore finish_lock_switch() to the exact state before the offending
patch and solve the problem differently.

Fixes: 2558aacff8 ("sched/hotplug: Ensure only per-cpu kthreads run during hotplug")
Reported-by: kernel test robot <oliver.sang@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20201210161408.GX3021@hirez.programming.kicks-ass.net

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This commit is contained in:

Peter Zijlstra 2020-12-10 17:14:08 +01:00

parent 5b78f2dc31

commit ae79270232

2 changed files with 20 additions and 33 deletions

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40

kernel/sched/core.c

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13

kernel/sched/sched.h

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