From: Alexander Shishkin Date: Thu, 19 Jan 2017 16:43:29 +0000 (+0200) Subject: perf/core: Don't re-schedule CPU flexible events needlessly X-Git-Url: http://git.cdn.openwrt.org/?a=commitdiff_plain;h=fe45bafbd0e1b5e828aa9d44d07e569df85869a2;p=openwrt%2Fstaging%2Fblogic.git perf/core: Don't re-schedule CPU flexible events needlessly In the sched-in path, we first remove a CPU's flexible events in order to give priority to the task's pinned events. However, this step can be safely skipped if the task doesn't have its own pinned events. This patch implements this skipping. Reported-by: Adrian Hunter Signed-off-by: Alexander Shishkin Signed-off-by: Peter Zijlstra (Intel) Cc: Arnaldo Carvalho de Melo Cc: Arnaldo Carvalho de Melo Cc: Jiri Olsa Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Stephane Eranian Cc: Thomas Gleixner Cc: Vince Weaver Cc: vince@deater.net Link: http://lkml.kernel.org/r/20170119164330.22887-2-alexander.shishkin@linux.intel.com Signed-off-by: Ingo Molnar --- diff --git a/kernel/events/core.c b/kernel/events/core.c index d92c7ad7715d..8c0b7334230b 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -3122,8 +3122,12 @@ static void perf_event_context_sched_in(struct perf_event_context *ctx, * We want to keep the following priority order: * cpu pinned (that don't need to move), task pinned, * cpu flexible, task flexible. + * + * However, if task's ctx is not carrying any pinned + * events, no need to flip the cpuctx's events around. */ - cpu_ctx_sched_out(cpuctx, EVENT_FLEXIBLE); + if (!list_empty(&ctx->pinned_groups)) + cpu_ctx_sched_out(cpuctx, EVENT_FLEXIBLE); perf_event_sched_in(cpuctx, ctx, task); perf_pmu_enable(ctx->pmu); perf_ctx_unlock(cpuctx, ctx);