Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752641Ab3EFDWh (ORCPT ); Sun, 5 May 2013 23:22:37 -0400 Received: from mail-pa0-f52.google.com ([209.85.220.52]:38083 "EHLO mail-pa0-f52.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752538Ab3EFDWg (ORCPT ); Sun, 5 May 2013 23:22:36 -0400 Message-ID: <518721F4.6050603@gmail.com> Date: Sun, 05 May 2013 21:22:28 -0600 From: David Ahern User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.7; rv:17.0) Gecko/20130328 Thunderbird/17.0.5 MIME-Version: 1.0 To: Namhyung Kim CC: Jiri Olsa , Arnaldo Carvalho de Melo , Peter Zijlstra , Paul Mackerras , Ingo Molnar , Namhyung Kim , LKML , Steven Rostedt , Frederic Weisbecker , Stephane Eranian Subject: Re: [PATCH 09/14] perf ftrace: Add 'record' sub-command References: <1366705872-12132-1-git-send-email-namhyung@kernel.org> <1366705872-12132-10-git-send-email-namhyung@kernel.org> <20130424141241.GG971@krava.brq.redhat.com> <87bo939lgt.fsf@sejong.aot.lge.com> <517A84B2.40209@gmail.com> <87ehdk98g6.fsf@sejong.aot.lge.com> In-Reply-To: <87ehdk98g6.fsf@sejong.aot.lge.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1037 Lines: 28 On 5/5/13 7:57 PM, Namhyung Kim wrote: > Hi David, > > On Fri, 26 Apr 2013 07:44:18 -0600, David Ahern wrote: >> On 4/25/13 12:24 AM, Namhyung Kim wrote: >>> But it looks there's a race between cond_wait() and cond_broatcast(). >>> I'll take a look at that. >> >> Why not use eventfd or a pipe for the signalling instead? > > Thanks for your feedback! > > I didn't have an idea of using eventfd for this case. Does it helpful > to prevent such a deadlock like this? I have used it to replace pthread_cond_wait / pthread_cond_{signal,broadcast} -- lighter and faster. It was added in 2.6.27 I believe, so will be available for any system that supports perf (record side). For people compiling perf against say RHEL5 (e.g. analysis) you will need a check as to whether it exists. David -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/