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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0E961C7EE2C for ; Fri, 25 Aug 2023 06:15:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S241606AbjHYGOf (ORCPT ); Fri, 25 Aug 2023 02:14:35 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34914 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S242153AbjHYGOX (ORCPT ); Fri, 25 Aug 2023 02:14:23 -0400 Received: from mgamail.intel.com (mgamail.intel.com [134.134.136.126]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 629F8269E; Thu, 24 Aug 2023 23:13:56 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1692944036; x=1724480036; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to:content-transfer-encoding; bh=LGBmzNZqpwqCz34Hf+ae1Pc+wHX56AyAU5nG1wmV35Q=; b=dZJoitGjClC7a7TCA6GDeHuJp99WaOHchRcZ/8WlyCJ29oZU3mSo36Ck ViPaOGUR/chfHUW9+GBKVbMYmFcocSju6pz3WWtemTlt68pCY+o98eWYU IhdPwN7gFDp/A8RzZv2KG4VTEWYJzyTVaEekybAOTZtjeqZoZheZvJzaA pgx9qHO0Zn6fE7BDxQDg1wGx3/KtW0N1VjBVrWaurMoubem16hB1NQG8I F4uYTFguu6MK/Nl0os2yShw7HJDEEKLhQr3SWY67vHcRrfTcIECnH0pWz 64NCogVbCXrPGzD+6gLnhuzltJXW/tShTmwqKMMDnTJVPj4kBj0l/3fjT g==; X-IronPort-AV: E=McAfee;i="6600,9927,10812"; a="359636888" X-IronPort-AV: E=Sophos;i="6.02,195,1688454000"; d="scan'208";a="359636888" Received: from fmsmga002.fm.intel.com ([10.253.24.26]) by orsmga106.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 24 Aug 2023 23:13:38 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10812"; a="851831176" X-IronPort-AV: E=Sophos;i="6.02,195,1688454000"; d="scan'208";a="851831176" Received: from ahunter6-mobl1.ger.corp.intel.com (HELO [10.0.2.15]) ([10.251.213.137]) by fmsmga002-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 24 Aug 2023 23:13:33 -0700 Message-ID: <90d877df-523e-6277-717e-9d63f2efccc5@intel.com> Date: Fri, 25 Aug 2023 09:13:28 +0300 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Firefox/102.0 Thunderbird/102.14.0 Subject: Re: [PATCH v6 4/7] perf record: Track sideband events for all CPUs when tracing selected CPUs Content-Language: en-US To: Ian Rogers , Yang Jihong Cc: peterz@infradead.org, mingo@redhat.com, acme@kernel.org, mark.rutland@arm.com, alexander.shishkin@linux.intel.com, jolsa@kernel.org, namhyung@kernel.org, kan.liang@linux.intel.com, james.clark@arm.com, tmricht@linux.ibm.com, ak@linux.intel.com, anshuman.khandual@arm.com, linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org References: <20230821012734.18241-1-yangjihong1@huawei.com> <20230821012734.18241-5-yangjihong1@huawei.com> From: Adrian Hunter Organization: Intel Finland Oy, Registered Address: PL 281, 00181 Helsinki, Business Identity Code: 0357606 - 4, Domiciled in Helsinki In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 25/08/23 08:17, Ian Rogers wrote: > On Sun, Aug 20, 2023 at 6:30 PM Yang Jihong wrote: >> >> User space tasks can migrate between CPUs, we need to track side-band >> events for all CPUs. >> >> The specific scenarios are as follows: >> >> CPU0 CPU1 >> perf record -C 0 start >> taskA starts to be created and executed >> -> PERF_RECORD_COMM and PERF_RECORD_MMAP >> events only deliver to CPU1 >> ...... >> | >> migrate to CPU0 >> | >> Running on CPU0 <----------/ >> ... >> >> perf record -C 0 stop >> >> Now perf samples the PC of taskA. However, perf does not record the >> PERF_RECORD_COMM and PERF_RECORD_MMAP events of taskA. >> Therefore, the comm and symbols of taskA cannot be parsed. >> >> The solution is to record sideband events for all CPUs when tracing >> selected CPUs. Because this modifies the default behavior, add related >> comments to the perf record man page. >> >> The sys_perf_event_open invoked is as follows: >> >> # perf --debug verbose=3 record -e cpu-clock -C 1 true >> >> Opening: cpu-clock >> ------------------------------------------------------------ >> perf_event_attr: >> type 1 (PERF_TYPE_SOFTWARE) >> size 136 >> config 0 (PERF_COUNT_SW_CPU_CLOCK) >> { sample_period, sample_freq } 4000 >> sample_type IP|TID|TIME|CPU|PERIOD|IDENTIFIER >> read_format ID|LOST >> disabled 1 >> inherit 1 >> freq 1 >> sample_id_all 1 >> exclude_guest 1 >> ------------------------------------------------------------ >> sys_perf_event_open: pid -1 cpu 1 group_fd -1 flags 0x8 = 5 >> Opening: dummy:u >> ------------------------------------------------------------ >> perf_event_attr: >> type 1 (PERF_TYPE_SOFTWARE) >> size 136 >> config 0x9 (PERF_COUNT_SW_DUMMY) >> { sample_period, sample_freq } 1 >> sample_type IP|TID|TIME|CPU|IDENTIFIER >> read_format ID|LOST >> inherit 1 >> exclude_kernel 1 >> exclude_hv 1 >> mmap 1 >> comm 1 >> task 1 >> sample_id_all 1 >> exclude_guest 1 >> mmap2 1 >> comm_exec 1 >> ksymbol 1 >> bpf_event 1 >> ------------------------------------------------------------ >> sys_perf_event_open: pid -1 cpu 0 group_fd -1 flags 0x8 = 6 >> sys_perf_event_open: pid -1 cpu 1 group_fd -1 flags 0x8 = 7 >> sys_perf_event_open: pid -1 cpu 2 group_fd -1 flags 0x8 = 9 >> sys_perf_event_open: pid -1 cpu 3 group_fd -1 flags 0x8 = 10 >> sys_perf_event_open: pid -1 cpu 4 group_fd -1 flags 0x8 = 11 >> sys_perf_event_open: pid -1 cpu 5 group_fd -1 flags 0x8 = 12 >> sys_perf_event_open: pid -1 cpu 6 group_fd -1 flags 0x8 = 13 >> sys_perf_event_open: pid -1 cpu 7 group_fd -1 flags 0x8 = 14 >> >> >> Signed-off-by: Yang Jihong >> Acked-by: Adrian Hunter >> --- >> tools/perf/Documentation/perf-record.txt | 3 ++ >> tools/perf/builtin-record.c | 44 +++++++++++++++++++++++- >> 2 files changed, 46 insertions(+), 1 deletion(-) >> >> diff --git a/tools/perf/Documentation/perf-record.txt b/tools/perf/Documentation/perf-record.txt >> index d5217be012d7..1889f66addf2 100644 >> --- a/tools/perf/Documentation/perf-record.txt >> +++ b/tools/perf/Documentation/perf-record.txt >> @@ -374,6 +374,9 @@ comma-separated list with no space: 0,1. Ranges of CPUs are specified with -: 0- >> In per-thread mode with inheritance mode on (default), samples are captured only when >> the thread executes on the designated CPUs. Default is to monitor all CPUs. >> >> +User space tasks can migrate between CPUs, so when tracing selected CPUs, >> +a dummy event is created to track sideband for all CPUs. >> + >> -B:: >> --no-buildid:: >> Do not save the build ids of binaries in the perf.data files. This skips >> diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c >> index 4ee94058028f..ae2e21b945fa 100644 >> --- a/tools/perf/builtin-record.c >> +++ b/tools/perf/builtin-record.c >> @@ -906,10 +906,44 @@ static int record__config_off_cpu(struct record *rec) >> return off_cpu_prepare(rec->evlist, &rec->opts.target, &rec->opts); >> } >> >> +static bool record__tracking_system_wide(struct record *rec) > > I think this would be better named something like: > record__need_system_wide_dummy_event Please no. The tracking event is a perf tool invention identified by evsel->tracking and used in evsel__config(). Please don't confuse it with dummy events. Just because the tracking event *might* be a dummy event does not mean a dummy event is the tracking event. > > Thanks, > Ian > >> +{ >> + struct record_opts *opts = &rec->opts; >> + struct evlist *evlist = rec->evlist; >> + struct evsel *evsel; >> + >> + /* >> + * If all (non-dummy) evsel have exclude_user, >> + * system_wide is not needed. >> + * >> + * all_kernel and all_user will overwrite exclude_kernel and >> + * exclude_user of attr in evsel__config(), here need to check >> + * all the three items. >> + * >> + * Sideband system wide if one of the following conditions is met: >> + * >> + * - all_user is set, and there is a non-dummy event >> + * - all_user and all_kernel are not set, and there is >> + * a non-dummy event without exclude_user >> + */ >> + if (opts->all_kernel) >> + return false; >> + >> + evlist__for_each_entry(evlist, evsel) { >> + if (!evsel__is_dummy_event(evsel)) { >> + if (opts->all_user || !evsel->core.attr.exclude_user) >> + return true; >> + } >> + } >> + >> + return false; >> +} >> + >> static int record__config_tracking_events(struct record *rec) >> { >> struct record_opts *opts = &rec->opts; >> struct evlist *evlist = rec->evlist; >> + bool system_wide = false; >> struct evsel *evsel; >> >> /* >> @@ -919,7 +953,15 @@ static int record__config_tracking_events(struct record *rec) >> */ >> if (opts->target.initial_delay || target__has_cpu(&opts->target) || >> perf_pmus__num_core_pmus() > 1) { >> - evsel = evlist__findnew_tracking_event(evlist, false); >> + >> + /* >> + * User space tasks can migrate between CPUs, so when tracing >> + * selected CPUs, sideband for all CPUs is still needed. >> + */ >> + if (!!opts->target.cpu_list && record__tracking_system_wide(rec)) >> + system_wide = true; >> + >> + evsel = evlist__findnew_tracking_event(evlist, system_wide); >> if (!evsel) >> return -ENOMEM; >> >> -- >> 2.30.GIT >>