From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754108AbcBCLwb (ORCPT ); Wed, 3 Feb 2016 06:52:31 -0500 Received: from e23smtp02.au.ibm.com ([202.81.31.144]:48685 "EHLO e23smtp02.au.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750935AbcBCLw3 (ORCPT ); Wed, 3 Feb 2016 06:52:29 -0500 X-IBM-Helo: d23dlp01.au.ibm.com X-IBM-MailFrom: srikar@linux.vnet.ibm.com X-IBM-RcptTo: linux-kernel@vger.kernel.org Date: Wed, 3 Feb 2016 17:21:21 +0530 From: Srikar Dronamraju To: Mel Gorman Cc: Ingo Molnar , Peter Zijlstra , Matt Fleming , Mike Galbraith , LKML Subject: Re: [PATCH 1/1] sched: Make schedstats a runtime tunable that is disabled by default v4 Message-ID: <20160203115121.GB28611@linux.vnet.ibm.com> Reply-To: Srikar Dronamraju References: <1454497668-22297-1-git-send-email-mgorman@techsingularity.net> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline In-Reply-To: <1454497668-22297-1-git-send-email-mgorman@techsingularity.net> User-Agent: Mutt/1.5.23 (2014-03-12) X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 16020311-0005-0000-0000-0000033FB86B Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > Changelog since v3 > o Force enable stats during profiling and latencytop > > Changelog since V2 > o Print stats that are not related to schedstat > o Reintroduce a static inline for update_stats_dequeue > > Changelog since V1 > o Introduce schedstat_enabled and address Ingo's feedback > o More schedstat-only paths eliminated, particularly ttwu_stat > > schedstats is very useful during debugging and performance tuning but it > incurs overhead. As such, even though it can be disabled at build time, > it is often enabled as the information is useful. This patch adds a > kernel command-line and sysctl tunable to enable or disable schedstats on > demand. It is disabled by default as someone who knows they need it can > also learn to enable it when necessary. > > The benefits are workload-dependent but when it gets down to it, the > difference will be whether cache misses are incurred updating the shared > stats or not. These measurements were taken from a 48-core 2-socket machine > with Xeon(R) E5-2670 v3 cpus although they were also tested on a single > socket machine 8-core machine with Intel i7-3770 processors. > > > Signed-off-by: Mel Gorman > Reviewed-by: Matt Fleming Reviewed-by: Srikar Dronamraju -- Thanks and Regards Srikar Dronamraju