From mboxrd@z Thu Jan 1 00:00:00 1970 Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751398AbeAEBPI (ORCPT + 1 other); Thu, 4 Jan 2018 20:15:08 -0500 Received: from mga09.intel.com ([134.134.136.24]:61446 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751100AbeAEBPG (ORCPT ); Thu, 4 Jan 2018 20:15:06 -0500 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.46,316,1511856000"; d="scan'208";a="16904363" Subject: Re: [PATCH v7 2/6] perf record: Get the first sample time and last sample time To: Arnaldo Carvalho de Melo Cc: 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 References: <1512738826-2628-1-git-send-email-yao.jin@linux.intel.com> <1512738826-2628-3-git-send-email-yao.jin@linux.intel.com> <20180104190903.GB20593@kernel.org> From: "Jin, Yao" Message-ID: Date: Fri, 5 Jan 2018 09:15:03 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.5.0 MIME-Version: 1.0 In-Reply-To: <20180104190903.GB20593@kernel.org> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Return-Path: On 1/5/2018 3:09 AM, Arnaldo Carvalho de Melo wrote: > Em Fri, Dec 08, 2017 at 09:13:42PM +0800, Jin Yao escreveu: >> In the default 'perf record' configuration, all samples are processed, >> to create the HEADER_BUILD_ID table. So it's very easy to get the >> first/last samples and save the time to perf file header via the >> function write_sample_time(). >> >> Later, at post processing time, perf report/script will fetch >> the time from perf file header. > > So, at this point I was expecting that that record would be present on > the perf.data file: > > [acme@jouet perf]$ perf record --timestamp-boundary sleep 1 > Cannot read kernel map > [ perf record: Woken up 1 times to write data ] > [ perf record: Captured and wrote 0.001 MB perf.data (7 samples) ] > [acme@jouet perf]$ perf report -D | grep PERF_RECORD_SAMPLE | wc -l > 7 > [acme@jouet perf]$ perf report -D | grep PERF_RECORD_SAMPLE_TIME > [acme@jouet perf]$ > > What am I doing wrong? > > To clarify, this is with just the first two patches in this series > applied. > > - Arnaldo > Hi Arnaldo, The timestamp boundary information is saved in perf file header. So if we want to look at them, we need to add '--header' in perf report. For example, root@skl:/tmp# perf report -D --header | grep 'time of' # time of first sample : 248333.706656 # time of last sample : 248357.215328 Thanks Jin Yao