From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751169AbeAVXCs (ORCPT ); Mon, 22 Jan 2018 18:02:48 -0500 Received: from mga05.intel.com ([192.55.52.43]:47412 "EHLO mga05.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751096AbeAVXCr (ORCPT ); Mon, 22 Jan 2018 18:02:47 -0500 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.46,398,1511856000"; d="scan'208";a="23834498" Subject: Re: [PATCH] perf util: Use target->per_thread and target->system_wide flags To: Mathieu Poirier Cc: Arnaldo Carvalho de Melo , jolsa@kernel.org, Peter Zijlstra , Ingo Molnar , Alexander Shishkin , Linux-kernel@vger.kernel.org, Andi Kleen , kan.liang@intel.com, yao.jin@intel.com References: <1516659340-30289-1-git-send-email-yao.jin@linux.intel.com> From: "Jin, Yao" Message-ID: <06929c28-6431-29f2-340e-6dbc2302c78b@linux.intel.com> Date: Tue, 23 Jan 2018 07:02:44 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.5.2 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 1/23/2018 5:10 AM, Mathieu Poirier wrote: > On 22 January 2018 at 15:15, Jin Yao wrote: >> Mathieu Poirier reports issue in commit ("73c0ca1eee3d perf thread_map: >> Enumerate all threads from /proc") that it has negative impact on >> 'perf record --per-thread'. It has the effect of creating a kernel event >> for each thread in the system for 'perf record --per-thread'. >> >> Mathieu Poirier's patch ("perf util: Do not reuse target->per_thread flag") >> can fix this issue by creating a new target->all_threads flag. >> >> This patch is based on Mathieu Poirier's patch but it doesn't use a new >> target->all_threads flag. This patch just uses 'target->per_thread && >> target->system_wide' as a condition to check for all threads case. >> >> Signed-off-by: Jin Yao >> --- >> tools/perf/util/evlist.c | 2 +- >> tools/perf/util/thread_map.c | 4 ++-- >> tools/perf/util/thread_map.h | 2 +- >> 3 files changed, 4 insertions(+), 4 deletions(-) >> >> diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c >> index 120efd8..9dff74a 100644 >> --- a/tools/perf/util/evlist.c >> +++ b/tools/perf/util/evlist.c >> @@ -1106,7 +1106,7 @@ int perf_evlist__create_maps(struct perf_evlist *evlist, struct target *target) >> struct thread_map *threads; >> >> threads = thread_map__new_str(target->pid, target->tid, target->uid, >> - target->per_thread); >> + target->per_thread && target->system_wide); > > At first glance I thought your solution would do the trick but perf > record does use target->system_wide when the '-a' switch is used. > Moreover specifying the '-a' switch doesn't prevent the '--per-thread' > option from being used as well, making both target->perf_thread and > target_system_wide equal to true (and that is not good). > > Although not a fan of adding more to struct target, the advantage of > having target->all_threads is that we are guaranteed that it isn't > used anywhere else. > > Let me know what you think, > Mathieu > If we specify both '-a' and '--per-thread' to perf record, perf record will override'--per-thread'. So now target->per_thread = false, and target->system_wide = true. If we specify '--per-thread' only to perf record, target->per_thread = true, and target->system_wide = false. So whatever for any case, target->per_thread && target->system_wide is false. Since the parameter is false, in thread_map__new_str(), it will not execute the thread_map__new_all_cpus(). So that will not change perf record previous behavior. In perf stat, it allows the case that target->per_thread and target->system_wide are all true. That means we want to collect system-wide per-thread metrics. That's my current thinking. Thanks Jin Yao