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=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 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 E887CC3815B for ; Mon, 20 Apr 2020 05:59:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id CCF79206F6 for ; Mon, 20 Apr 2020 05:59:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726023AbgDTF7q (ORCPT ); Mon, 20 Apr 2020 01:59:46 -0400 Received: from mga09.intel.com ([134.134.136.24]:45725 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725825AbgDTF7p (ORCPT ); Mon, 20 Apr 2020 01:59:45 -0400 IronPort-SDR: fMmPfR19ScC9zSb9mnKkcRZU7FG4G9qKHIYgMjiZKqJKT2uxL/f3UKK8BIWa8ncMqCfgzYlZ51 ctMFhXNrUfSQ== X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga001.fm.intel.com ([10.253.24.23]) by orsmga102.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 19 Apr 2020 22:59:45 -0700 IronPort-SDR: uT1v7V7Rcx6uAaoiD6cmuffkUv7dWjDLTPGLYvAHBhO2Z2XMEm14Slcprh7FpcUsf1wgMl9Vsd GL/o71cHVSTg== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.72,405,1580803200"; d="scan'208";a="364904229" Received: from yjin15-mobl1.ccr.corp.intel.com (HELO [10.238.4.151]) ([10.238.4.151]) by fmsmga001.fm.intel.com with ESMTP; 19 Apr 2020 22:59:42 -0700 Subject: Re: [PATCH] perf stat: Improve runtime stat for interval mode To: kajoljain , acme@kernel.org, jolsa@kernel.org, peterz@infradead.org, mingo@redhat.com, alexander.shishkin@linux.intel.com Cc: Linux-kernel@vger.kernel.org, ak@linux.intel.com, kan.liang@intel.com, yao.jin@intel.com References: <20200417005154.9024-1-yao.jin@linux.intel.com> <4950a109-ff2f-7199-c0f7-5b39ddc5afbb@linux.ibm.com> From: "Jin, Yao" Message-ID: Date: Mon, 20 Apr 2020 13:59:41 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.7.0 MIME-Version: 1.0 In-Reply-To: <4950a109-ff2f-7199-c0f7-5b39ddc5afbb@linux.ibm.com> Content-Type: text/plain; charset=utf-8; format=flowed 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 On 4/20/2020 1:48 PM, kajoljain wrote: > > > On 4/17/20 6:21 AM, Jin Yao wrote: >> For interval mode, the metric is printed after # if it exists. But >> it's not calculated by the counts generated in this interval. See >> following examples, >> >> root@kbl-ppc:~# perf stat -M CPI -I1000 --interval-count 2 >> # time counts unit events >> 1.000422803 764,809 inst_retired.any # 2.9 CPI >> 1.000422803 2,234,932 cycles >> 2.001464585 1,960,061 inst_retired.any # 1.6 CPI >> 2.001464585 4,022,591 cycles >> >> The second CPI should not be 1.6 (4,022,591/1,960,061 is 2.1) >> >> root@kbl-ppc:~# perf stat -e cycles,instructions -I1000 --interval-count 2 >> # time counts unit events >> 1.000429493 2,869,311 cycles >> 1.000429493 816,875 instructions # 0.28 insn per cycle >> 2.001516426 9,260,973 cycles >> 2.001516426 5,250,634 instructions # 0.87 insn per cycle >> >> The second 'insn per cycle' should not be 0.87 (5,250,634/9,260,973 is 0.57). >> >> The current code uses a global variable rt_stat for tracking and >> updating the std dev of runtime stat. Unlike the counts, rt_stat is >> not reset for interval. While the counts are reset for interval. >> >> perf_stat_process_counter() >> { >> if (config->interval) >> init_stats(ps->res_stats); >> } >> >> So for interval, the rt_stat should be reset either. >> >> This patch resets rt_stat before read_counters, so the runtime >> stat is only calculated by the counts generated in this interval. >> >> With this patch, >> >> root@kbl-ppc:~# perf stat -M CPI -I1000 --interval-count 2 >> # time counts unit events >> 1.000420924 2,408,818 inst_retired.any # 2.1 CPI >> 1.000420924 5,010,111 cycles >> 2.001448579 2,798,407 inst_retired.any # 1.6 CPI >> 2.001448579 4,599,861 cycles >> >> root@kbl-ppc:~# perf stat -e cycles,instructions -I1000 --interval-count 2 >> # time counts unit events >> 1.000428555 2,769,714 cycles >> 1.000428555 774,462 instructions # 0.28 insn per cycle >> 2.001471562 3,595,904 cycles >> 2.001471562 1,243,703 instructions # 0.35 insn per cycle >> > > Hi Jin, > Thanks for the patch. Was working on similar issue raised by Joakim Zhang. > Here's link to my findings: https://lkml.org/lkml/2020/3/24/158 > > This patch solves the issue. > > Acked-By: Kajol Jain and Tested-By: Kajol Jain > Thanks for testing this patch. :) Thanks Jin Yao >> Now the second 'insn per cycle' and CPI are calculated by the counts >> generated in this interval. >> >> Signed-off-by: Jin Yao >> --- >> tools/perf/Documentation/perf-stat.txt | 2 ++ >> tools/perf/builtin-stat.c | 1 + >> tools/perf/util/stat-shadow.c | 5 +++++ >> tools/perf/util/stat.h | 1 + >> 4 files changed, 9 insertions(+) >> >> diff --git a/tools/perf/Documentation/perf-stat.txt b/tools/perf/Documentation/perf-stat.txt >> index 4d56586b2fb9..3fb5028aef08 100644 >> --- a/tools/perf/Documentation/perf-stat.txt >> +++ b/tools/perf/Documentation/perf-stat.txt >> @@ -176,6 +176,8 @@ Print count deltas every N milliseconds (minimum: 1ms) >> The overhead percentage could be high in some cases, for instance with small, sub 100ms intervals. Use with caution. >> example: 'perf stat -I 1000 -e cycles -a sleep 5' >> >> +If the metric exists, it is calculated by the counts generated in this interval and the metric is printed after #. >> + >> --interval-count times:: >> Print count deltas for fixed number of times. >> This option should be used together with "-I" option. >> diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c >> index ec053dc1e35c..d5c326ff46d0 100644 >> --- a/tools/perf/builtin-stat.c >> +++ b/tools/perf/builtin-stat.c >> @@ -359,6 +359,7 @@ static void process_interval(void) >> clock_gettime(CLOCK_MONOTONIC, &ts); >> diff_timespec(&rs, &ts, &ref_time); >> >> + perf_stat__reset_rt_stat(); >> read_counters(&rs); >> >> if (STAT_RECORD) { >> diff --git a/tools/perf/util/stat-shadow.c b/tools/perf/util/stat-shadow.c >> index 1ad5c5be7e97..c8f5ca6c8749 100644 >> --- a/tools/perf/util/stat-shadow.c >> +++ b/tools/perf/util/stat-shadow.c >> @@ -186,6 +186,11 @@ void perf_stat__reset_shadow_stats(void) >> memset(&walltime_nsecs_stats, 0, sizeof(walltime_nsecs_stats)); >> } >> >> +void perf_stat__reset_rt_stat(void) >> +{ >> + reset_stat(&rt_stat); >> +} >> + >> void perf_stat__reset_shadow_per_stat(struct runtime_stat *st) >> { >> reset_stat(st); >> diff --git a/tools/perf/util/stat.h b/tools/perf/util/stat.h >> index b4fdfaa7f2c0..2975494166dd 100644 >> --- a/tools/perf/util/stat.h >> +++ b/tools/perf/util/stat.h >> @@ -176,6 +176,7 @@ void runtime_stat__init(struct runtime_stat *st); >> void runtime_stat__exit(struct runtime_stat *st); >> void perf_stat__init_shadow_stats(void); >> void perf_stat__reset_shadow_stats(void); >> +void perf_stat__reset_rt_stat(void); >> void perf_stat__reset_shadow_per_stat(struct runtime_stat *st); >> void perf_stat__update_shadow_stats(struct evsel *counter, u64 count, >> int cpu, struct runtime_stat *st); >>