From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752858AbbIRNh3 (ORCPT ); Fri, 18 Sep 2015 09:37:29 -0400 Received: from foss.arm.com ([217.140.101.70]:46309 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751068AbbIRNh1 (ORCPT ); Fri, 18 Sep 2015 09:37:27 -0400 Date: Fri, 18 Sep 2015 14:37:09 +0100 From: Mark Rutland To: Adrian Hunter Cc: Arnaldo Carvalho de Melo , "linux-kernel@vger.kernel.org" , Ingo Molnar , Jiri Olsa , Peter Zijlstra Subject: Re: [PATCH] perf tools: session: avoid infinite loop Message-ID: <20150918133708.GA26468@leverpostej> References: <1442423929-12253-1-git-send-email-mark.rutland@arm.com> <20150916205454.GI11551@kernel.org> <20150917154152.GD12808@leverpostej> <55FBAA8C.2020703@intel.com> <20150918095112.GA21286@leverpostej> <55FBED85.8020603@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <55FBED85.8020603@intel.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > > So it looks like I shouldn't have any synthesized events. Have I missed > > anything? > > Yes, you are right. But you are not getting the COMM and MMAP events from > the exec which means you are killing perf before it execs the workload. Oh, I see. > Perf writes through a pipe to its forked child to do the exec, so > to reproduce it you just need to put everything on the same cpu and play around > with the sleep number > > taskset -c 0 tools/perf/perf record -- sleep 1 & sleep 0.005 ; kill -2 $! > > reproduces the problem for me. Of course, since the workload doesn't get exec'ed > it doesn't matter if it is bogus i.e. > > taskset -c 0 tools/perf/perf record -- sdfgsdgdg & sleep 0.005 ; kill -2 $! > > also reproduces the problem. Thanks for confirming! Mark.