From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756616AbdKDKY0 (ORCPT ); Sat, 4 Nov 2017 06:24:26 -0400 Received: from mx1.redhat.com ([209.132.183.28]:57262 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751987AbdKDKYY (ORCPT ); Sat, 4 Nov 2017 06:24:24 -0400 DMARC-Filter: OpenDMARC Filter v1.3.2 mx1.redhat.com 65D10C0587C3 Authentication-Results: ext-mx08.extmail.prod.ext.phx2.redhat.com; dmarc=none (p=none dis=none) header.from=redhat.com Authentication-Results: ext-mx08.extmail.prod.ext.phx2.redhat.com; spf=fail smtp.mailfrom=jolsa@redhat.com Date: Sat, 4 Nov 2017 11:24:21 +0100 From: Jiri Olsa To: Arnaldo Carvalho de Melo Cc: "Jin, Yao" , jolsa@kernel.org, peterz@infradead.org, mingo@redhat.com, alexander.shishkin@linux.intel.com, Linux-kernel@vger.kernel.org, ak@linux.intel.com, kan.liang@intel.com, yao.jin@intel.com Subject: Re: [PATCH v5 2/6] perf record: Get the first sample time and last sample time Message-ID: <20171104102421.GA7511@krava> References: <1508542074-29483-1-git-send-email-yao.jin@linux.intel.com> <1508542074-29483-3-git-send-email-yao.jin@linux.intel.com> <20171023150436.GA10746@krava> <818cd5bf-fd40-444e-4f4d-c9e25cf90b51@linux.intel.com> <20171024071659.GB27972@krava> <20171103162942.GF3531@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20171103162942.GF3531@kernel.org> User-Agent: Mutt/1.9.1 (2017-09-22) X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.32]); Sat, 04 Nov 2017 10:24:24 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Nov 03, 2017 at 01:29:42PM -0300, Arnaldo Carvalho de Melo wrote: > Em Tue, Oct 24, 2017 at 09:16:59AM +0200, Jiri Olsa escreveu: > > On Tue, Oct 24, 2017 at 10:03:05AM +0800, Jin, Yao wrote: > > > > SNIP > > > > > > hum, could you still unset the sample if there's no time given? > > > > and keep the speed in this case.. > > > > > > > > jirka > > > > > > > > > > Hi Jiri, > > > > > > I check this question again. The '--time' option is for perf report but not > > > for perf record. > > > > > > For perf record, we have to always walk on all samples to get the time of > > > first sample and the time of last sample whatever buildid_all is enabled or > > > not enabled. So 'rec->tool.sample = NULL' is removed. > > > > > > Sorry, the previous mail was replied at midnight, I was drowsy. :( > > > > > > If my answer is correct, I will not send v6. If my understanding is still > > > not correct, please let me know. > > > > right, I did not realize we store this unconditionaly.. then yes, it's ok > > And should we store this unconditionally? What this patch is doing is > making 'perf record' unconditionally slower so that the generated > perf.data file becomes useful for some usecases, but not for all, only > people interested in using 'perf report/script --time' will benefit, > right? maybe we can also silently enable that when processing buildids, (which is set by default), there's no big performance hit once we already go through samples jirka > > I thought that we could get this sorted out in a different fashion, i.e. > getting the first timestamp is easy, even if we don't process build-ids, > right? To get the last one we could ask the kernel to insert an extra > dummy sample at the end, one that we know the size and thus can to to > the end of the file, rewind that size, get the event and parse the > sample, agreed? > > So I suggest that first make this conditional, i.e. 'perf record > --timestamps' will enable the logic you implemented, and as a followup, > if you agree, add the dummy, known size event at the end, and then even > when build-ids are not processed, the cost for getting the timestamps > will be next to zero. > > - Arnaldo > > - Arnaldo > > > I think I've already acked this, anyway for the patchset: > > > > Acked-by: Jiri Olsa > > > > thanks, > > jirka