Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755892Ab1BKJ4e (ORCPT ); Fri, 11 Feb 2011 04:56:34 -0500 Received: from smtp-out.google.com ([74.125.121.67]:43384 "EHLO smtp-out.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755241Ab1BKJ4c convert rfc822-to-8bit (ORCPT ); Fri, 11 Feb 2011 04:56:32 -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=YoVb9S46U2E2WTWNDniIBfVEBtup7TyESdG1C6yvUN0UpGA2GDhAW+W3cbmLygjuWO +/gUgdVDydlVLJIjogZg== MIME-Version: 1.0 In-Reply-To: <4D548904.9000003@cn.fujitsu.com> 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 10:56:28 +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: 2061 Lines: 49 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. -- 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/