sched: Optimize finish_lock_switch()
The kernel test robot measured a -1.6% performance regression on will-it-scale/sched_yield due to commit: 2558aacf ("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: 2558aacf ("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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