Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932091AbbFLOVv (ORCPT ); Fri, 12 Jun 2015 10:21:51 -0400 Received: from mail-qc0-f169.google.com ([209.85.216.169]:33741 "EHLO mail-qc0-f169.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753458AbbFLOVt (ORCPT ); Fri, 12 Jun 2015 10:21:49 -0400 Message-ID: <557AEAF9.5050507@gmail.com> Date: Fri, 12 Jun 2015 08:21:45 -0600 From: David Ahern User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.10; rv:31.0) Gecko/20100101 Thunderbird/31.7.0 MIME-Version: 1.0 To: Adrian Hunter CC: Peter Zijlstra , Andi Kleen , Arnaldo Carvalho de Melo , Ingo Molnar , linux-kernel@vger.kernel.org, Jiri Olsa , Stephane Eranian , mathieu.poirier@linaro.org, Pawel Moll Subject: Re: [RFC PATCH] perf: Add PERF_RECORD_SWITCH to indicate context switches References: <1433859670-10806-1-git-send-email-adrian.hunter@intel.com> <20150611141548.GW19282@twins.programming.kicks-ass.net> <557A2C14.4010804@gmail.com> <557AB5D1.9050905@intel.com> In-Reply-To: <557AB5D1.9050905@intel.com> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1357 Lines: 28 On 6/12/15 4:34 AM, Adrian Hunter wrote: > On 12/06/15 03:47, David Ahern wrote: >> On 6/11/15 8:15 AM, Peter Zijlstra wrote: >>>> This new PERF_RECORD_SWITCH event does not have those problems >>>> and it also has a couple of other small advantages. It is >>>> easier to use because it is an auxiliary event (like mmap, >>>> comm and task events) which can be enabled by setting a single >>>> bit. It is smaller than sched:sched_switch and easier to parse. >>> >>> Right, so the one wee problem I have is that this only provides sched_in >>> data, I imagine people might be interested in sched_out as well. >> >> Yes and with the option of collecting callchains for sched_out. > > So what do you want that is different different from > PERF_COUNT_SW_CONTEXT_SWITCHES? And why? > My 'perf sched timehist' command can use either sched_switch and context switches. As you have pointed out you need to collect them system wide even if you only care about a subset of tasks. If you are going to add a sched_in there is good symmetry by also having a sched_out that is used and generated in a consistent manner. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/