From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752040Ab2AYTvT (ORCPT ); Wed, 25 Jan 2012 14:51:19 -0500 Received: from mx0b-00082601.pphosted.com ([67.231.153.30]:57988 "EHLO mx0a-00082601.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751089Ab2AYTvS (ORCPT ); Wed, 25 Jan 2012 14:51:18 -0500 Message-ID: <4F205D1D.1020304@fb.com> Date: Wed, 25 Jan 2012 11:50:53 -0800 From: Arun Sharma User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.7; rv:8.0) Gecko/20111105 Thunderbird/8.0 MIME-Version: 1.0 To: Frederic Weisbecker CC: Peter Zijlstra , , Arnaldo Carvalho de Melo , Andrew Vagin , Ingo Molnar , Steven Rostedt Subject: Re: [PATCH] trace: reset sleep/block start time on task switch References: <1327026020-32376-1-git-send-email-asharma@fb.com> <1327318449.2446.5.camel@twins> <4F1DA9D0.6090208@fb.com> <1327352631.2446.22.camel@twins> <4F1DE6FE.4000603@fb.com> <1327415255.2614.33.camel@laptop> <4F1F26CC.4040109@fb.com> <20120125092008.GB20878@somewhere> In-Reply-To: <20120125092008.GB20878@somewhere> Content-Type: text/plain; charset="ISO-8859-1"; format=flowed Content-Transfer-Encoding: 7bit X-Originating-IP: [192.168.18.252] X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:5.6.7361,1.0.211,0.0.0000 definitions=2012-01-25_08:2012-01-25,2012-01-25,1970-01-01 signatures=0 X-Proofpoint-Spam-Reason: safe Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 1/25/12 1:20 AM, Frederic Weisbecker wrote: >>> I'm tempted to revert 1ac9bc69 for now, userspace will simply have to >>> correlate trace_sched_switch() and trace_sched_stat_{sleep,blocked}(), >>> which shouldn't be too hard. >> >> We tried it and it didn't work very well. Especially when used with >> perf record -g. There are too many uninteresting >> trace_sched_switch() events. > > You mean context switches happening when the prev task doesn't need > to block or so? As it happens with preemption for example? > > In this case you can use filters to drop context switches for > which the prev state is not S or D. We had these filters and still couldn't keep up: # perf record -agP -e sched:sched_switch --filter "prev_state == 1 || prev_state == 2" -e sched:sched_stat_sleep -- sleep 3 [ perf record: Woken up 107 times to write data ] [ perf record: Captured and wrote 32.629 MB perf.data (~1425585 samples) ] Warning: Processed 104066 events and lost 4 chunks! Check IO/CPU overload! -Arun