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=-11.5 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_2 autolearn=unavailable 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 429D6C433FE for ; Fri, 17 Jul 2020 17:01:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1B57720704 for ; Fri, 17 Jul 2020 17:01:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728285AbgGQRBb (ORCPT ); Fri, 17 Jul 2020 13:01:31 -0400 Received: from mail.kernel.org ([198.145.29.99]:43350 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728183AbgGQRB2 (ORCPT ); Fri, 17 Jul 2020 13:01:28 -0400 Received: from oasis.local.home (cpe-66-24-58-225.stny.res.rr.com [66.24.58.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id BBD9E207DD; Fri, 17 Jul 2020 17:01:26 +0000 (UTC) Date: Fri, 17 Jul 2020 13:01:24 -0400 From: Steven Rostedt To: Changbin Du Cc: Arnaldo Carvalho de Melo , Jiri Olsa , Peter Zijlstra , Ingo Molnar , Namhyung Kim , linux-kernel@vger.kernel.org Subject: Re: [PATCH v5 03/17] perf ftrace: add option -t/--tid to filter by thread id Message-ID: <20200717130124.54e85349@oasis.local.home> In-Reply-To: <20200717132650.i32oovllal22b35i@mail.google.com> References: <20200711124035.6513-1-changbin.du@gmail.com> <20200711124035.6513-4-changbin.du@gmail.com> <20200716153630.GD374956@kernel.org> <20200717132650.i32oovllal22b35i@mail.google.com> X-Mailer: Claws Mail 3.17.3 (GTK+ 2.24.32; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 17 Jul 2020 21:26:50 +0800 Changbin Du wrote: > On Thu, Jul 16, 2020 at 12:36:30PM -0300, Arnaldo Carvalho de Melo wrote: > > Em Sat, Jul 11, 2020 at 08:40:21PM +0800, Changbin Du escreveu: > > > This allows us to trace single thread instead of the whole process. > > > > > > Signed-off-by: Changbin Du > > > --- > > > tools/perf/Documentation/perf-ftrace.txt | 4 ++++ > > > tools/perf/builtin-ftrace.c | 2 ++ > > > 2 files changed, 6 insertions(+) > > > > > > diff --git a/tools/perf/Documentation/perf-ftrace.txt b/tools/perf/Documentation/perf-ftrace.txt > > > index d79560dea19f..e204bf6d50d8 100644 > > > --- a/tools/perf/Documentation/perf-ftrace.txt > > > +++ b/tools/perf/Documentation/perf-ftrace.txt > > > @@ -38,6 +38,10 @@ OPTIONS > > > --pid=:: > > > Trace on existing process id (comma separated list). > > > > > > +-t:: > > > +--tid=:: > > > + Trace on existing thread id (comma separated list). > > > + > > > > > > Humm, I just tried: > > > > [root@five ~]# yes > /dev/null & > > [1] 18265 > > [root@five ~]# perf ftrace --tid 18265 > > ^C[root@five ~]# > > > > After waiting for a while, nothing, what am I doing wrong? > > > I got it wrong. Currently ftrace only can filter by pid. If the pid is not > the main thread it won't work. Wait what? The "pid" for ftrace is really a "task id" which is a thread id. [root@bxtest ~]# yes > /dev/null & [1] 6799 [root@bxtest ~]# trace-cmd record -e all -P 6799 Hit Ctrl^C to stop recording ^CCPU 0: 3573031 events lost CPU0 data recorded at offset=0x838000 627675136 bytes in size CPU1 data recorded at offset=0x25ed1000 0 bytes in size CPU2 data recorded at offset=0x25ed1000 0 bytes in size CPU3 data recorded at offset=0x25ed1000 0 bytes in size CPU4 data recorded at offset=0x25ed1000 0 bytes in size CPU5 data recorded at offset=0x25ed1000 0 bytes in size CPU6 data recorded at offset=0x25ed1000 0 bytes in size CPU7 data recorded at offset=0x25ed1000 0 bytes in size [root@bxtest ~]# trace-cmd report | head CPU 1 is empty CPU 2 is empty CPU 3 is empty CPU 4 is empty CPU 5 is empty CPU 6 is empty CPU 7 is empty cpus=8 yes-6799 [000] 67825.580902: sys_exit: NR 1 = 8192 yes-6799 [000] 67825.580903: sys_exit_write: 0x2000 What's different about tid vs pid? -- Steve > > So this patch makes no sense. will drop this. >