Commit 13d5a5e9 authored Nov 30, 2020 by Mel Gorman Committed by Ingo Molnar Dec 11, 2020

sched/fair: Clear SMT siblings after determining the core is not idle

The clearing of SMT siblings from the SIS mask before checking for an idle
core is a small but unnecessary cost. Defer the clearing of the siblings
until the scan moves to the next potential target. The cost of this was
not measured as it is borderline noise but it should be self-evident.

Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lkml.kernel.org/r/20201130144020.GS3371@techsingularity.net

parent 59a74b15

kernel/sched/fair.c

+2 −1

Original line number	Diff line number	Diff line
		@@ -6086,10 +6086,11 @@ static int select_idle_core(struct task_struct p, struct sched_domain sd, int
		break;
		}
		}
		cpumask_andnot(cpus, cpus, cpu_smt_mask(core));

		if (idle)
		return core;

		cpumask_andnot(cpus, cpus, cpu_smt_mask(core));
		}

		/*