From mboxrd@z Thu Jan 1 00:00:00 1970 From: Milian Wolff Subject: Re: Perf event for Wall-time based sampling? Date: Fri, 19 Sep 2014 16:39:39 +0200 Message-ID: <1423473.AV2A0F0SQn@milian-kdab2> References: <2221771.b2oSN5LR6X@milian-kdab2> <20140918203625.GM2770@kernel.org> <541C3B0B.3030706@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7Bit Return-path: Received: from dd17628.kasserver.com ([85.13.138.83]:46355 "EHLO dd17628.kasserver.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757190AbaISOjm (ORCPT ); Fri, 19 Sep 2014 10:39:42 -0400 In-Reply-To: <541C3B0B.3030706@gmail.com> Sender: linux-perf-users-owner@vger.kernel.org List-ID: To: David Ahern Cc: Arnaldo Carvalho de Melo , linux-perf-users , Namhyung Kim , Ingo Molnar , Joseph Schuchart On Friday 19 September 2014 08:17:47 David Ahern wrote: > On 9/18/14, 2:36 PM, Arnaldo Carvalho de Melo wrote: > > Ok, so you want to see what is the wait channel and unwind the stack > > from there? Is that the case? I.e. again, a sysrq-t equivalent? > > > >> Milian want is to grab samples every timer expiration even if process is > >> not running. > > > > What for? And by "grab samples" you want to know where it is waiting for > > something, together with its callchain? > > > >> Any limitations that would prevent doing this with a sw event? e.g, mimic > >> task-clock just don't disable the timer when the task is scheduled out. > > > > I'm just trying to figure out if what people want is a complete > > backtrace of all threads in a process, no matter what they are doing, at > > some given time, i.e. at "sysrq-t" time, is that the case? > > This has been discussed before: > http://thread.gmane.org/gmane.linux.kernel/1307306 > > Example on the perf wiki: > https://perf.wiki.kernel.org/index.php/Tutorial#Profiling_sleep_times Right, I also mentioned this in my initial email. This is _not_ what I want though :) Bye -- Milian Wolff mail@milianw.de http://milianw.de