From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753030AbbE0KE1 (ORCPT ); Wed, 27 May 2015 06:04:27 -0400 Received: from terminus.zytor.com ([198.137.202.10]:33456 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752975AbbE0KEV (ORCPT ); Wed, 27 May 2015 06:04:21 -0400 Date: Wed, 27 May 2015 03:03:49 -0700 From: tip-bot for Thomas Gleixner Message-ID: Cc: peterz@infradead.org, hpa@zytor.com, torvalds@linux-foundation.org, linux-kernel@vger.kernel.org, matt.fleming@intel.com, will.auld@intel.com, vikas.shivappa@linux.intel.com, tglx@linutronix.de, mingo@kernel.org, kanaka.d.juvva@intel.com Reply-To: hpa@zytor.com, peterz@infradead.org, torvalds@linux-foundation.org, matt.fleming@intel.com, linux-kernel@vger.kernel.org, vikas.shivappa@linux.intel.com, tglx@linutronix.de, kanaka.d.juvva@intel.com, mingo@kernel.org, will.auld@intel.com In-Reply-To: <20150518235150.080844281@linutronix.de> References: <20150518235150.080844281@linutronix.de> To: linux-tip-commits@vger.kernel.org Subject: [tip:perf/core] perf/x86/intel/cqm: Avoid pointless MSR write Git-Commit-ID: 0bac237845e203dd1439cfc571b1baf1b2274b3b 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 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: 0bac237845e203dd1439cfc571b1baf1b2274b3b Gitweb: http://git.kernel.org/tip/0bac237845e203dd1439cfc571b1baf1b2274b3b Author: Thomas Gleixner AuthorDate: Tue, 19 May 2015 00:00:55 +0000 Committer: Ingo Molnar CommitDate: Wed, 27 May 2015 09:17:40 +0200 perf/x86/intel/cqm: Avoid pointless MSR write If the usage counter is non-zero there is no point to update the rmid in the PQR MSR. Signed-off-by: Thomas Gleixner Signed-off-by: Peter Zijlstra (Intel) Acked-by: Matt Fleming Cc: Kanaka Juvva Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Vikas Shivappa Cc: Will Auld Link: http://lkml.kernel.org/r/20150518235150.080844281@linutronix.de Signed-off-by: Ingo Molnar --- arch/x86/kernel/cpu/perf_event_intel_cqm.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/arch/x86/kernel/cpu/perf_event_intel_cqm.c b/arch/x86/kernel/cpu/perf_event_intel_cqm.c index 63391f8..2ce69c0 100644 --- a/arch/x86/kernel/cpu/perf_event_intel_cqm.c +++ b/arch/x86/kernel/cpu/perf_event_intel_cqm.c @@ -974,10 +974,12 @@ static void intel_cqm_event_start(struct perf_event *event, int mode) event->hw.cqm_state &= ~PERF_HES_STOPPED; - if (state->cnt++) - WARN_ON_ONCE(state->rmid != rmid); - else + if (state->cnt++) { + if (!WARN_ON_ONCE(state->rmid != rmid)) + return; + } else { WARN_ON_ONCE(state->rmid); + } state->rmid = rmid; /*