Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933033AbZLRVOR (ORCPT ); Fri, 18 Dec 2009 16:14:17 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932658AbZLRVON (ORCPT ); Fri, 18 Dec 2009 16:14:13 -0500 Received: from casper.infradead.org ([85.118.1.10]:35050 "EHLO casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932648AbZLRVOE (ORCPT ); Fri, 18 Dec 2009 16:14:04 -0500 Subject: Re: [PATCH 1/1] perf record: We should fork only if a program was specified to run From: Peter Zijlstra To: Arnaldo Carvalho de Melo Cc: Ingo Molnar , linux-kernel@vger.kernel.org, =?ISO-8859-1?Q?Fr=E9d=E9ric?= Weisbecker , Mike Galbraith , Paul Mackerras In-Reply-To: <20091218205853.GD19708@ghostprotocols.net> References: <1261168944-6615-1-git-send-email-acme@infradead.org> <1261169561.20899.630.camel@laptop> <20091218205853.GD19708@ghostprotocols.net> Content-Type: text/plain; charset="UTF-8" Date: Fri, 18 Dec 2009 22:13:38 +0100 Message-ID: <1261170818.20899.657.camel@laptop> Mime-Version: 1.0 X-Mailer: Evolution 2.28.1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2539 Lines: 72 On Fri, 2009-12-18 at 18:58 -0200, Arnaldo Carvalho de Melo wrote: > Em Fri, Dec 18, 2009 at 09:52:41PM +0100, Peter Zijlstra escreveu: > > On Fri, 2009-12-18 at 18:42 -0200, Arnaldo Carvalho de Melo wrote: > > > From: Arnaldo Carvalho de Melo > > > @@ -422,7 +422,8 @@ static int __cmd_record(int argc __used, const char **argv) > > > signal(SIGCHLD, sig_handler); > > > signal(SIGINT, sig_handler); > > > > > > - if (pipe(child_ready_pipe) < 0 || pipe(go_pipe) < 0) { > > > + if (target_pid == -1 && argc > 0 && > > > + (pipe(child_ready_pipe) < 0 || pipe(go_pipe) < 0)) { > > > perror("failed to create pipes"); > > > exit(-1); > > > } > > > > Why bother? > > Because we don't need it? Well its a rare error, and the paranoid in me says bailing asap avoids funny cases later. > > > @@ -483,7 +484,7 @@ static int __cmd_record(int argc __used, const char **argv) > > > > > > atexit(atexit_header); > > > > > > - if (target_pid == -1) { > > > + if (target_pid == -1 && argc > 0) { > > > pid = fork(); > > > if (pid < 0) { > > > perror("failed to fork"); > > > > I'd write: > > > > target_pid == -1 && !system_wide > > Because we want this to work: > > [root@doppio linux-2.6-tip]# perf record -a -f sleep 2 > [ perf record: Woken up 1 times to write data ] > [ perf record: Captured and wrote 0.243 MB perf.data (~10599 samples) ] > [root@doppio linux-2.6-tip]# > > See, no hands mother! I.e. it is system wide, but just for 2 seconds, > its clever, but I like it, and it always worked :-) Ah, right.. yes, totally forgot about that. > > > @@ -667,7 +668,7 @@ int cmd_record(int argc, const char **argv, const char *prefix __used) > > > > > > argc = parse_options(argc, argv, options, record_usage, > > > PARSE_OPT_STOP_AT_NON_OPTION); > > > - if (!argc && target_pid == -1 && (!system_wide || profile_cpu == -1)) > > > + if (!argc && target_pid == -1 && !system_wide) > > > usage_with_options(record_usage, options); > > > > > > symbol__init(); > > > > Right, so I was thinking -C would be enough to also start profiling.. > > clearly messed up the logic though :/ > > Yeah, it should, meaning "profile everything on CPU N" Right, so I tried folding that in and goofed up. Anyway, patch looks ok, thanks! -- 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/