Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756366Ab1BKNg2 (ORCPT ); Fri, 11 Feb 2011 08:36:28 -0500 Received: from smtp-out.google.com ([74.125.121.67]:24835 "EHLO smtp-out.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755478Ab1BKNg0 convert rfc822-to-8bit (ORCPT ); Fri, 11 Feb 2011 08:36:26 -0500 DomainKey-Signature: a=rsa-sha1; c=nofws; d=google.com; s=beta; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type:content-transfer-encoding; b=Riovwx6tXnf9OhE7jnzpkP2ufZ5ejAeJekv6+AYU3leXX6GebfnKqlhQzQPAph8rvZ K03GJZxb/btcg2kRWOdQ== MIME-Version: 1.0 In-Reply-To: References: <4d384700.2308e30a.70bc.ffffd532@mx.google.com> <1297095037.13327.47.camel@laptop> <1297244844.13327.155.camel@laptop> <4D548904.9000003@cn.fujitsu.com> Date: Fri, 11 Feb 2011 14:36:18 +0100 Message-ID: Subject: Re: [PATCH 1/2] perf_events: add cgroup support (v8) From: Stephane Eranian To: Li Zefan Cc: Peter Zijlstra , linux-kernel@vger.kernel.org, mingo@elte.hu, paulus@samba.org, davem@davemloft.net, fweisbec@gmail.com, perfmon2-devel@lists.sf.net, eranian@gmail.com, robert.richter@amd.com, acme@redhat.com, Paul Menage Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT X-System-Of-Record: true Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2711 Lines: 61 On Fri, Feb 11, 2011 at 10:56 AM, Stephane Eranian wrote: > Li, > > On Fri, Feb 11, 2011 at 1:55 AM, Li Zefan wrote: >>>>> while there is already cgroup monitoring active. In that case and if we do not >>>>> want to wait until there is at least one ctxsw on all CPUs, then we have to >>>>> check if the other threads are not already running on the other CPUs.If so, >>>>> we need to do a cgroup switch on those CPUs. Otherwise, we have nothing to >>>>> do. Am I getting this right? >>>> >>>> Right, so if any of those tasks is currently running, that cpu will be >>>> monitoring their old cgroup, hence we send an IPI to flip cgroups. >>>> >>> I have built a test case where this would trigger. I launched a multi-threaded >>> app, and then I move the pid into a cgroup via: echo PID >/cgroup/tests/tasks. >>> I don't see any perf_cgroup move beyond the PID passed. >>> >>> I looked at kernel/cgroup.c and I could not find a invocation of >>> ss->attach() that >>> would pass threadgroup = true. So I am confused here. >>> >>> I wonder how the cgroupfs 'echo PID >tasks' interface would make the distinction >>> between PID and TID. It seems possible to move one thread of a multi-threaded >>> process into a cgroup but not the others. >>> >> >> You can do this: >> >>        # echo PID > cgroup.procs >> >> When the patchset that implements the above feature is accepted. See: >> >>        https://lkml.org/lkml/2011/2/7/418 >> >> The below commit that confused you is actually a part of the above patchset, >> but it sneaked into the kernel accidentally: >> >> commit be367d09927023d081f9199665c8500f69f14d22 >> Author: Ben Blum >> Date:   Wed Sep 23 15:56:31 2009 -0700 >> >>    cgroups: let ss->can_attach and ss->attach do whole threadgroups at a time >> > Ok, that makes more sense now. I wil try with the above patchset applied to > verify this work as expected. > The above patchset seems to work fine. I add to switch perf_event from ss->attach() to ss->attach_task() to make it work with multi-threaded apps. The good thing is that it simplifies the code, because all we have to do now is simply call perf_cgroup_move(). The caller does the thread iteration. During this exercise, I found a minor issue in event_sched_out() with the current perf cgroup patch. I will resubmit the patch incl. Peter's changes + some more cleanups and the fix + the update perf cgroup patch. 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/