From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754037AbdASQyc (ORCPT ); Thu, 19 Jan 2017 11:54:32 -0500 Received: from mga05.intel.com ([192.55.52.43]:44978 "EHLO mga05.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753790AbdASQya (ORCPT ); Thu, 19 Jan 2017 11:54:30 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.33,254,1477983600"; d="scan'208";a="810888714" From: Alexander Shishkin To: Peter Zijlstra Cc: Ingo Molnar , linux-kernel@vger.kernel.org, vince@deater.net, eranian@google.com, Arnaldo Carvalho de Melo , Alexander Shishkin Subject: [PATCH 1/2] perf: Don't re-schedule cpu flexible events needlessly Date: Thu, 19 Jan 2017 18:43:29 +0200 Message-Id: <20170119164330.22887-2-alexander.shishkin@linux.intel.com> X-Mailer: git-send-email 2.11.0 In-Reply-To: <20170119164330.22887-1-alexander.shishkin@linux.intel.com> References: <20170119164330.22887-1-alexander.shishkin@linux.intel.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org In the sched-in path, we first remove cpu's flexible events in order to give priority to 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. Signed-off-by: Alexander Shishkin Reported-by: Adrian Hunter --- kernel/events/core.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/kernel/events/core.c b/kernel/events/core.c index dedfd3078c..c196b9537f 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -3137,8 +3137,12 @@ 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); -- 2.11.0