From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753223AbcLLPV6 (ORCPT ); Mon, 12 Dec 2016 10:21:58 -0500 Received: from mail.kernel.org ([198.145.29.136]:56760 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752366AbcLLPV5 (ORCPT ); Mon, 12 Dec 2016 10:21:57 -0500 Date: Mon, 12 Dec 2016 12:21:49 -0300 From: Arnaldo Carvalho de Melo To: Jiri Olsa Cc: Jiri Olsa , David Ahern , Namhyung Kim , Peter Zijlstra , lkml , Ingo Molnar Subject: Re: [PATCH 4/5] perf tools: Allow to ignore missing pid Message-ID: <20161212152149.GA5482@kernel.org> References: <1481538943-21874-1-git-send-email-jolsa@kernel.org> <1481538943-21874-5-git-send-email-jolsa@kernel.org> <20161212143209.GB5650@kernel.org> <20161212145312.GA28361@krava> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20161212145312.GA28361@krava> X-Url: http://acmel.wordpress.com User-Agent: Mutt/1.7.1 (2016-10-04) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Em Mon, Dec 12, 2016 at 03:53:12PM +0100, Jiri Olsa escreveu: > On Mon, Dec 12, 2016 at 11:32:09AM -0300, Arnaldo Carvalho de Melo wrote: > > Em Mon, Dec 12, 2016 at 11:35:42AM +0100, Jiri Olsa escreveu: > > > Adding perf_evsel::ignore_missing_cpu_thread bool. > > > > > > When set true, it allows perf to ignore error of missing > > > pid of perf event syscall. > > > > > > We remove missing thread id from the thread_map, so the > > > rest of the processing like ioctl and mmap won't get > > > disturbed with -1 fd > > > > What was the test performed? I tried it here the following while doing > > a 'make -j4 allmodconfig' in the background, i.e. tons of threads coming > > and going, and I sometimes get: > > > > [root@jouet ~]# perf record -u acme > > Error: > > The sys_perf_event_open() syscall returned with 3 (No such process) for > > event (cycles:ppp). > > /bin/dmesg may provide additional information. > > No CONFIG_PERF_EVENTS=y kernel support configured? > > I dont think it's fast enough (start/stop) to hit the race, I've got best > results with having on background this: > > while :; do /usr/bin/true; done Ok, but the focus of my message wasn't on generating threads, was in having the above happen with your patch applied. - Arnaldo