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=-11.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 E43ABC433FF for ; Thu, 8 Aug 2019 20:17:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A71A62173E for ; Thu, 8 Aug 2019 20:17:58 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=zytor.com header.i=@zytor.com header.b="gxyvdHIs" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2404664AbfHHUR5 (ORCPT ); Thu, 8 Aug 2019 16:17:57 -0400 Received: from terminus.zytor.com ([198.137.202.136]:47745 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2404324AbfHHUR5 (ORCPT ); Thu, 8 Aug 2019 16:17:57 -0400 Received: from terminus.zytor.com (localhost [127.0.0.1]) by terminus.zytor.com (8.15.2/8.15.2) with ESMTPS id x78KHnFF3320927 (version=TLSv1.3 cipher=TLS_AES_256_GCM_SHA384 bits=256 verify=NO); Thu, 8 Aug 2019 13:17:49 -0700 DKIM-Filter: OpenDKIM Filter v2.11.0 terminus.zytor.com x78KHnFF3320927 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=zytor.com; s=2019071901; t=1565295469; bh=fY2A8QyFB0MqLBtu43yiHTYb2DT3d2bFrT7eQ8fwCMk=; h=Date:From:Cc:Reply-To:In-Reply-To:References:To:Subject:From; b=gxyvdHIsvjFil+jgmz4POLPwlRTyRCijnGIllnK0PCOqVqrpeAk/KSi6DYj3euIIn nBVyccMIb+C4ZiRrargqGUFLu+LrsSA3GNIURlu/YAlmONZbbIhf62fAPZHFm+k2du N5DNXtEuzvA4/b8WxvTuahGxnExhYm/Vz0UMjv7+1iP4VmYmwT8cJXKKjiaUsH2t4m so1L1WVhLUQqEO+j32uH3+HfWBXgzGPeZ0OsWfxUz7xyJUhUBRyesjylWYMQKIzGaK ytW95lZZLNf1FAhDToea1r3f5zRlTZweKaASUJR9FbUKkroigUG9Y8YJ0VVAhSLB0G QXRCPA4HQlctg== Received: (from tipbot@localhost) by terminus.zytor.com (8.15.2/8.15.2/Submit) id x78KHmaW3320924; Thu, 8 Aug 2019 13:17:48 -0700 Date: Thu, 8 Aug 2019 13:17:48 -0700 X-Authentication-Warning: terminus.zytor.com: tipbot set sender to tipbot@zytor.com using -f From: tip-bot for Adrian Hunter Message-ID: Cc: jolsa@redhat.com, acme@redhat.com, linux-kernel@vger.kernel.org, adrian.hunter@intel.com, mingo@kernel.org, hpa@zytor.com, tglx@linutronix.de Reply-To: linux-kernel@vger.kernel.org, adrian.hunter@intel.com, acme@redhat.com, jolsa@redhat.com, mingo@kernel.org, hpa@zytor.com, tglx@linutronix.de In-Reply-To: <20190808064823.14846-1-adrian.hunter@intel.com> References: <20190808064823.14846-1-adrian.hunter@intel.com> To: linux-tip-commits@vger.kernel.org Subject: [tip:perf/urgent] perf db-export: Fix thread__exec_comm() Git-Commit-ID: 3de7ae0b2a1d86dbb23d0cb135150534fdb2e836 X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: 3de7ae0b2a1d86dbb23d0cb135150534fdb2e836 Gitweb: https://git.kernel.org/tip/3de7ae0b2a1d86dbb23d0cb135150534fdb2e836 Author: Adrian Hunter AuthorDate: Thu, 8 Aug 2019 09:48:23 +0300 Committer: Arnaldo Carvalho de Melo CommitDate: Thu, 8 Aug 2019 15:41:10 -0300 perf db-export: Fix thread__exec_comm() Threads synthesized from /proc have comms with a start time of zero, and not marked as "exec". Currently, there can be 2 such comms. The first is created by processing a synthesized fork event and is set to the parent's comm string, and the second by processing a synthesized comm event set to the thread's current comm string. In the absence of an "exec" comm, thread__exec_comm() picks the last (oldest) comm, which, in the case above, is the parent's comm string. For a main thread, that is very probably wrong. Use the second-to-last in that case. This affects only db-export because it is the only user of thread__exec_comm(). Example: $ sudo perf record -a -o pt-a-sleep-1 -e intel_pt//u -- sleep 1 $ sudo chown ahunter pt-a-sleep-1 Before: $ perf script -i pt-a-sleep-1 --itrace=bep -s tools/perf/scripts/python/export-to-sqlite.py pt-a-sleep-1.db branches calls $ sqlite3 -header -column pt-a-sleep-1.db 'select * from comm_threads_view' comm_id command thread_id pid tid ---------- ---------- ---------- ---------- ---------- 1 swapper 1 0 0 2 rcu_sched 2 10 10 3 kthreadd 3 78 78 5 sudo 4 15180 15180 5 sudo 5 15180 15182 7 kworker/4: 6 10335 10335 8 kthreadd 7 55 55 10 systemd 8 865 865 10 systemd 9 865 875 13 perf 10 15181 15181 15 sleep 10 15181 15181 16 kworker/3: 11 14179 14179 17 kthreadd 12 29376 29376 19 systemd 13 746 746 21 systemd 14 401 401 23 systemd 15 879 879 23 systemd 16 879 945 25 kthreadd 17 556 556 27 kworker/u1 18 14136 14136 28 kworker/u1 19 15021 15021 29 kthreadd 20 509 509 31 systemd 21 836 836 31 systemd 22 836 967 33 systemd 23 1148 1148 33 systemd 24 1148 1163 35 kworker/2: 25 17988 17988 36 kworker/0: 26 13478 13478 After: $ perf script -i pt-a-sleep-1 --itrace=bep -s tools/perf/scripts/python/export-to-sqlite.py pt-a-sleep-1b.db branches calls $ sqlite3 -header -column pt-a-sleep-1b.db 'select * from comm_threads_view' comm_id command thread_id pid tid ---------- ---------- ---------- ---------- ---------- 1 swapper 1 0 0 2 rcu_sched 2 10 10 3 kswapd0 3 78 78 4 perf 4 15180 15180 4 perf 5 15180 15182 6 kworker/4: 6 10335 10335 7 kcompactd0 7 55 55 8 accounts-d 8 865 865 8 accounts-d 9 865 875 10 perf 10 15181 15181 12 sleep 10 15181 15181 13 kworker/3: 11 14179 14179 14 kworker/1: 12 29376 29376 15 haveged 13 746 746 16 systemd-jo 14 401 401 17 NetworkMan 15 879 879 17 NetworkMan 16 879 945 19 irq/131-iw 17 556 556 20 kworker/u1 18 14136 14136 21 kworker/u1 19 15021 15021 22 kworker/u1 20 509 509 23 thermald 21 836 836 23 thermald 22 836 967 25 unity-sett 23 1148 1148 25 unity-sett 24 1148 1163 27 kworker/2: 25 17988 17988 28 kworker/0: 26 13478 13478 Signed-off-by: Adrian Hunter Cc: Jiri Olsa Cc: stable@vger.kernel.org Fixes: 65de51f93ebf ("perf tools: Identify which comms are from exec") Link: http://lkml.kernel.org/r/20190808064823.14846-1-adrian.hunter@intel.com Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/util/thread.c | 12 +++++++++++- 1 file changed, 11 insertions(+), 1 deletion(-) diff --git a/tools/perf/util/thread.c b/tools/perf/util/thread.c index 873ab505ca80..590793cc5142 100644 --- a/tools/perf/util/thread.c +++ b/tools/perf/util/thread.c @@ -214,14 +214,24 @@ struct comm *thread__comm(const struct thread *thread) struct comm *thread__exec_comm(const struct thread *thread) { - struct comm *comm, *last = NULL; + struct comm *comm, *last = NULL, *second_last = NULL; list_for_each_entry(comm, &thread->comm_list, list) { if (comm->exec) return comm; + second_last = last; last = comm; } + /* + * 'last' with no start time might be the parent's comm of a synthesized + * thread (created by processing a synthesized fork event). For a main + * thread, that is very probably wrong. Prefer a later comm to avoid + * that case. + */ + if (second_last && !last->start && thread->pid_ == thread->tid) + return second_last; + return last; }