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=-7.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS 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 F1097C282E9 for ; Mon, 21 Jan 2019 08:02:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C84392084A for ; Mon, 21 Jan 2019 08:02:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729323AbfAUIC6 (ORCPT ); Mon, 21 Jan 2019 03:02:58 -0500 Received: from mga09.intel.com ([134.134.136.24]:39583 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729202AbfAUIC4 (ORCPT ); Mon, 21 Jan 2019 03:02:56 -0500 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga003.jf.intel.com ([10.7.209.27]) by orsmga102.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 20 Jan 2019 17:40:48 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.56,501,1539673200"; d="scan'208";a="120012112" Received: from yjin15-mobl.ccr.corp.intel.com (HELO [10.239.159.76]) ([10.239.159.76]) by orsmga003.jf.intel.com with ESMTP; 20 Jan 2019 17:40:46 -0800 Subject: Re: [PATCH v2] Poll for monitored tasks being alive in fork mode To: Jiri Olsa , acme@kernel.org 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: <1546822850-30649-1-git-send-email-yao.jin@linux.intel.com> <20190107090522.GA3383@krava> From: "Jin, Yao" Message-ID: <460f52d2-2061-8fe3-9c9a-1709d3e49343@linux.intel.com> Date: Mon, 21 Jan 2019 09:40:45 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.4.0 MIME-Version: 1.0 In-Reply-To: <20190107090522.GA3383@krava> 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 Hi Arnaldo, Is this patch acceptable? Thanks Jin Yao On 1/7/2019 5:05 PM, Jiri Olsa wrote: > On Mon, Jan 07, 2019 at 09:00:50AM +0800, Jin Yao wrote: >> Following test shows the stat keeps running even if no longer >> task to monitor (mgen exits at ~5s). >> >> perf stat -e cycles -p `pgrep mgen` -I1000 -- sleep 10 >> time counts unit events >> 1.000148916 1,308,365,864 cycles >> 2.000379171 1,297,269,875 cycles >> 3.000556719 1,297,187,078 cycles >> 4.000914241 761,261,827 cycles >> 5.001306091 cycles >> 6.001676881 cycles >> 7.002046336 cycles >> 8.002405651 cycles >> 9.002766625 cycles >> 10.001395827 cycles >> >> We'd better finish stat immediately if there's no longer task to >> monitor. >> >> After: >> >> perf stat -e cycles -p `pgrep mgen` -I1000 -- sleep 10 >> time counts unit events >> 1.000180062 1,236,592,661 cycles >> 2.000421539 1,223,733,572 cycles >> 3.000609910 1,297,047,663 cycles >> 4.000807545 1,297,215,816 cycles >> 5.001001578 1,297,208,032 cycles >> 6.001390345 582,343,659 cycles >> sleep: Terminated >> >> Now the stat exits immediately when the monitored tasks ends. >> >> v2: >> --- >> There is a potential race condition window, that is the >> child_pid set with -1 and kill(-1, SIGTERM) may happen. >> Jiri provides a simple method which stores the child_pid to >> a local variable and check the local variable before kill(). >> At least, we can avoid the kill(-1, SIGTERM) case. >> >> Signed-off-by: Jin Yao > > Reviewed-by: Jiri Olsa > > thanks, > jirka > >> --- >> tools/perf/builtin-stat.c | 9 +++++++++ >> 1 file changed, 9 insertions(+) >> >> diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c >> index 63a3afc..bd5fb8e 100644 >> --- a/tools/perf/builtin-stat.c >> +++ b/tools/perf/builtin-stat.c >> @@ -553,6 +553,15 @@ static int __run_perf_stat(int argc, const char **argv, int run_idx) >> >> if (interval || timeout) { >> while (!waitpid(child_pid, &status, WNOHANG)) { >> + if (!is_target_alive(&target, >> + evsel_list->threads)) { >> + int pid = child_pid; >> + >> + if (pid != -1) >> + kill(pid, SIGTERM); >> + break; >> + } >> + >> nanosleep(&ts, NULL); >> if (timeout) >> break; >> -- >> 2.7.4 >>