From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755653Ab3HPSsk (ORCPT ); Fri, 16 Aug 2013 14:48:40 -0400 Received: from terminus.zytor.com ([198.137.202.10]:40420 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755542Ab3HPSsY (ORCPT ); Fri, 16 Aug 2013 14:48:24 -0400 Date: Fri, 16 Aug 2013 11:47:56 -0700 From: tip-bot for Peter Zijlstra Message-ID: Cc: linux-kernel@vger.kernel.org, hpa@zytor.com, mingo@kernel.org, peterz@infradead.org, tglx@linutronix.de Reply-To: mingo@kernel.org, hpa@zytor.com, linux-kernel@vger.kernel.org, peterz@infradead.org, tglx@linutronix.de In-Reply-To: <20130802191630.GT27162@twins.programming.kicks-ass.net> References: <20130802191630.GT27162@twins.programming.kicks-ass.net> To: linux-tip-commits@vger.kernel.org Subject: [tip:perf/core] perf: Do not compute time values unnecessarily Git-Commit-ID: 5ec4c599a52362896c3e7c6a31ba6145dca9c6f5 X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.2.7 (terminus.zytor.com [127.0.0.1]); Fri, 16 Aug 2013 11:48:01 -0700 (PDT) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: 5ec4c599a52362896c3e7c6a31ba6145dca9c6f5 Gitweb: http://git.kernel.org/tip/5ec4c599a52362896c3e7c6a31ba6145dca9c6f5 Author: Peter Zijlstra AuthorDate: Fri, 2 Aug 2013 21:16:30 +0200 Committer: Ingo Molnar CommitDate: Fri, 16 Aug 2013 17:55:52 +0200 perf: Do not compute time values unnecessarily We should not be calling calc_timer_values() for events that do not actually have an mmap()'ed userpage. Signed-off-by: Peter Zijlstra Link: http://lkml.kernel.org/r/20130802191630.GT27162@twins.programming.kicks-ass.net Signed-off-by: Ingo Molnar --- kernel/events/core.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/kernel/events/core.c b/kernel/events/core.c index 2e675e8..928fae7 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -3670,6 +3670,10 @@ void perf_event_update_userpage(struct perf_event *event) u64 enabled, running, now; rcu_read_lock(); + rb = rcu_dereference(event->rb); + if (!rb) + goto unlock; + /* * compute total_time_enabled, total_time_running * based on snapshot values taken when the event @@ -3680,12 +3684,8 @@ void perf_event_update_userpage(struct perf_event *event) * NMI context */ calc_timer_values(event, &now, &enabled, &running); - rb = rcu_dereference(event->rb); - if (!rb) - goto unlock; userpg = rb->user_page; - /* * Disable preemption so as to not let the corresponding user-space * spin too long if we get preempted.