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 9F900C001DC for ; Mon, 31 Jul 2023 11:08:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232062AbjGaLIN (ORCPT ); Mon, 31 Jul 2023 07:08:13 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55242 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232075AbjGaLIL (ORCPT ); Mon, 31 Jul 2023 07:08:11 -0400 Received: from mgamail.intel.com (unknown [134.134.136.100]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8D606E76; Mon, 31 Jul 2023 04:08:09 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1690801689; x=1722337689; h=message-id:date:mime-version:subject:to:references:from: in-reply-to:content-transfer-encoding; bh=wmHhhDZYj/HzDaojK6j8984a8pR+yl+cuphjT9plJ/I=; b=IMPt2f5ecdyuxNXngky+ZOAdFsuyXpO3Xd05vGrxM6cSAIiv4ljCWVCT PEhOJTjDx1YHhjgtbXM9jjIM5a+0n6HcO8CoTMHWGWdbynsWx0ozqMGqQ g7WDrEhrCkaqd70HbmNNEIo9aWAVdO9s/rv7UC9iDBSHSKbJV2B8+BDbW jKgLt8MqmFtEf5xvLSg8STiuSnO6kcVNEMBf5ctv3dkKelCYHLzonXv/B veYLf6Sbmg5i4APNRqEHqNwIjUI/3VI4umbJ6aC+m5Ukjit5nVzNQjBzj sQDEvCS8HPHAd5Z074xl23S10CRvJdvK5CfShTfAAXgGqSOEavSUSoE8B g==; X-IronPort-AV: E=McAfee;i="6600,9927,10787"; a="435293007" X-IronPort-AV: E=Sophos;i="6.01,244,1684825200"; d="scan'208";a="435293007" Received: from orsmga004.jf.intel.com ([10.7.209.38]) by orsmga105.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 31 Jul 2023 04:08:08 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10787"; a="852001627" X-IronPort-AV: E=Sophos;i="6.01,244,1684825200"; d="scan'208";a="852001627" Received: from ahunter6-mobl1.ger.corp.intel.com (HELO [10.0.2.15]) ([10.251.208.223]) by orsmga004-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 31 Jul 2023 04:08:04 -0700 Message-ID: <4ec5cf9e-130d-4259-420f-420508186858@intel.com> Date: Mon, 31 Jul 2023 14:08:00 +0300 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Firefox/102.0 Thunderbird/102.13.1 Subject: Re: [PATCH v3 4/7] perf record: Track sideband events for all CPUs when tracing selected CPUs Content-Language: en-US To: Yang Jihong , peterz@infradead.org, mingo@redhat.com, acme@kernel.org, mark.rutland@arm.com, alexander.shishkin@linux.intel.com, jolsa@kernel.org, namhyung@kernel.org, irogers@google.com, 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: <20230722093219.174898-1-yangjihong1@huawei.com> <20230722093219.174898-5-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: <20230722093219.174898-5-yangjihong1@huawei.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 22/07/23 12:32, 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 > --- > tools/perf/Documentation/perf-record.txt | 3 +++ > tools/perf/builtin-record.c | 14 +++++++++++++- > 2 files changed, 16 insertions(+), 1 deletion(-) > > diff --git a/tools/perf/Documentation/perf-record.txt b/tools/perf/Documentation/perf-record.txt > index 680396c56bd1..dac53ece51ab 100644 > --- a/tools/perf/Documentation/perf-record.txt > +++ b/tools/perf/Documentation/perf-record.txt > @@ -388,6 +388,9 @@ 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 3ff9d972225e..4e8e97928f05 100644 > --- a/tools/perf/builtin-record.c > +++ b/tools/perf/builtin-record.c > @@ -912,6 +912,7 @@ 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; > > /* > @@ -921,7 +922,18 @@ 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 all (non-dummy) evsel have exclude_user, > + * system_wide is not needed. > + */ > + if (!!opts->target.cpu_list && !opts->all_kernel) Not everyone uses all-kernel. Can we check the evsels are either dummy or exclude_user? > + system_wide = true; > + > + evsel = evlist__findnew_tracking_event(evlist, system_wide); > if (!evsel) > return -ENOMEM; >