From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760978AbcAKQgS (ORCPT ); Mon, 11 Jan 2016 11:36:18 -0500 Received: from bombadil.infradead.org ([198.137.202.9]:46808 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759764AbcAKQe5 (ORCPT ); Mon, 11 Jan 2016 11:34:57 -0500 Message-Id: <20160111163228.728460494@infradead.org> User-Agent: quilt/0.61-1 Date: Mon, 11 Jan 2016 17:25:00 +0100 From: Peter Zijlstra To: mingo@kernel.org, alexander.shishkin@linux.intel.com, eranian@google.com Cc: linux-kernel@vger.kernel.org, vince@deater.net, dvyukov@google.com, andi@firstfloor.org, jolsa@redhat.com, peterz@infradead.org Subject: [RFC][PATCH 02/12] perf: Fix cgroup event scheduling References: <20160111162458.427203780@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline; filename=peterz-perf-fixes-2.patch Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org There appears to be a problemin __perf_event_task_sched_in() wrt cgroup event scheduling. The normal event scheduling order is: CPU pinned Task pinned CPU flexible Task flexible And since perf_cgroup_sched*() only schedules the cpu context, we must call this _before_ adding the task events. Note: double check what happens on the ctx switch optimization where the task ctx isn't scheduled. Cc: Stephane Eranian Signed-off-by: Peter Zijlstra (Intel) --- kernel/events/core.c | 17 ++++++++++------- 1 file changed, 10 insertions(+), 7 deletions(-) --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -2804,6 +2804,16 @@ void __perf_event_task_sched_in(struct t struct perf_event_context *ctx; int ctxn; + /* + * If cgroup events exist on this CPU, then we need to check if we have + * to switch in PMU state; cgroup event are system-wide mode only. + * + * Since cgroup events are CPU events, we must schedule these in before + * we schedule in the task events. + */ + if (atomic_read(this_cpu_ptr(&perf_cgroup_events))) + perf_cgroup_sched_in(prev, task); + for_each_task_context_nr(ctxn) { ctx = task->perf_event_ctxp[ctxn]; if (likely(!ctx)) @@ -2811,13 +2821,6 @@ void __perf_event_task_sched_in(struct t perf_event_context_sched_in(ctx, task); } - /* - * if cgroup events exist on this CPU, then we need - * to check if we have to switch in PMU state. - * cgroup event are system-wide mode only - */ - if (atomic_read(this_cpu_ptr(&perf_cgroup_events))) - perf_cgroup_sched_in(prev, task); if (atomic_read(&nr_switch_events)) perf_event_switch(task, prev, true);