From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1004EC433F5 for ; Wed, 5 Sep 2018 17:39:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id BE64720857 for ; Wed, 5 Sep 2018 17:39:15 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org BE64720857 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.intel.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727745AbeIEWKZ (ORCPT ); Wed, 5 Sep 2018 18:10:25 -0400 Received: from mga09.intel.com ([134.134.136.24]:37774 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726497AbeIEWKY (ORCPT ); Wed, 5 Sep 2018 18:10:24 -0400 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga003.fm.intel.com ([10.253.24.29]) by orsmga102.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 05 Sep 2018 10:39:12 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.53,334,1531810800"; d="scan'208";a="78228466" Received: from linux.intel.com ([10.54.29.200]) by FMSMGA003.fm.intel.com with ESMTP; 05 Sep 2018 10:37:37 -0700 Received: from [10.252.23.215] (unknown [10.252.23.215]) by linux.intel.com (Postfix) with ESMTP id EEA9E5801AB; Wed, 5 Sep 2018 10:37:34 -0700 (PDT) Subject: Re: [PATCH v7 0/2]: perf: reduce data loss when profiling highly parallel CPU bound workloads To: Jiri Olsa Cc: Ingo Molnar , Peter Zijlstra , Arnaldo Carvalho de Melo , Alexander Shishkin , Namhyung Kim , Andi Kleen , linux-kernel References: <1fc1fc5b-a8cc-2b05-d43c-692e58855c81@linux.intel.com> <20180905112851.GA29759@krava> From: Alexey Budankov Organization: Intel Corp. Message-ID: <34e2f944-f5f3-094a-5997-899cea92d206@linux.intel.com> Date: Wed, 5 Sep 2018 20:37:32 +0300 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: <20180905112851.GA29759@krava> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, On 05.09.2018 14:28, Jiri Olsa wrote: > On Wed, Sep 05, 2018 at 10:16:42AM +0300, Alexey Budankov wrote: >> >> Currently in record mode the tool implements trace writing serially. >> The algorithm loops over mapped per-cpu data buffers and stores >> ready data chunks into a trace file using write() system call. >> >> At some circumstances the kernel may lack free space in a buffer >> because the other buffer's half is not yet written to disk due to >> some other buffer's data writing by the tool at the moment. >> >> Thus serial trace writing implementation may cause the kernel >> to loose profiling data and that is what observed when profiling >> highly parallel CPU bound workloads on machines with big number >> of cores. >> >> Experiment with profiling matrix multiplication code executing 128 >> threads on Intel Xeon Phi (KNM) with 272 cores, like below, >> demonstrates data loss metrics value of 98%: >> >> /usr/bin/time perf record -o /tmp/perf-ser.data -a -N -B -T -R -g \ >> --call-graph dwarf,1024 --user-regs=IP,SP,BP \ >> --switch-events -e cycles,instructions,ref-cycles,software/period=1,name=cs,config=0x3/Duk -- \ >> matrix.gcc >> >> Data loss metrics is the ratio lost_time/elapsed_time where >> lost_time is the sum of time intervals containing PERF_RECORD_LOST >> records and elapsed_time is the elapsed application run time >> under profiling. >> >> Applying asynchronous trace streaming thru Posix AIO API >> (http://man7.org/linux/man-pages/man7/aio.7.html) >> lowers data loss metrics value providing 2x improvement - >> lowering 98% loss to almost 0%. >> >> --- >> Alexey Budankov (2): >> perf util: map data buffer for preserving collected data >> perf record: enable asynchronous trace writing >> >> tools/perf/builtin-record.c | 197 +++++++++++++++++++++++++++++++++++++++++++- >> tools/perf/perf.h | 1 + >> tools/perf/util/evlist.c | 7 +- >> tools/perf/util/evlist.h | 3 +- >> tools/perf/util/mmap.c | 110 +++++++++++++++++++++---- >> tools/perf/util/mmap.h | 10 ++- >> 6 files changed, 302 insertions(+), 26 deletions(-) >> >> --- >> Changes in v7: >> - implemented handling record.aio setting from perfconfig file > > can't apply this version on Arnaldo's perf/core... my git remote -v origin git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip (fetch) origin git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip (push) branch is perf/core, according to MAINTAINERS content. What is Arnaldo's perf/core? This one? git://git.kernel.org/pub/scm/linux/kernel/git/acme/linux and branch is perf/core? > > [jolsa@krava linux-perf]$ git am /tmp/ab/ > Applying: perf util: map data buffer for preserving collected data > error: patch failed: tools/perf/util/mmap.c:166 > error: tools/perf/util/mmap.c: patch does not apply > > thanks, > jirka >