From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757682Ab2AECIi (ORCPT ); Wed, 4 Jan 2012 21:08:38 -0500 Received: from cn.fujitsu.com ([222.73.24.84]:58618 "EHLO song.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1757099Ab2AECIg (ORCPT ); Wed, 4 Jan 2012 21:08:36 -0500 Message-ID: <4F0506B1.1070909@cn.fujitsu.com> Date: Thu, 05 Jan 2012 10:10:57 +0800 From: Li Zefan User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9.2.9) Gecko/20100921 Fedora/3.1.4-1.fc14 Thunderbird/3.1.4 MIME-Version: 1.0 To: Mandeep Singh Baines CC: Tejun Heo , Frederic Weisbecker , linux-kernel@vger.kernel.org, containers@lists.linux-foundation.org, cgroups@vger.kernel.org, KAMEZAWA Hiroyuki , Oleg Nesterov , Andrew Morton , Paul Menage Subject: Re: [PATCH 3/3] cgroup: remove extra calls to find_existing_css_set References: <1325654312-32477-1-git-send-email-msb@chromium.org> <1325654312-32477-3-git-send-email-msb@chromium.org> In-Reply-To: <1325654312-32477-3-git-send-email-msb@chromium.org> X-MIMETrack: Itemize by SMTP Server on mailserver/fnst(Release 8.5.1FP4|July 25, 2010) at 2012-01-05 10:07:38, Serialize by Router on mailserver/fnst(Release 8.5.1FP4|July 25, 2010) at 2012-01-05 10:07:40, Serialize complete at 2012-01-05 10:07:40 Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Mandeep Singh Baines wrote: > In cgroup_attach_proc, we indirectly call find_existing_css_set 3 > times. It is an expensive call so we want to call it a minimum > of times. This patch only calls it once and stores the result so > that it can be used later on when we call cgroup_task_migrate. > > This required modifying cgroup_task_migrate to take the new css_set > (which we obtained from find_css_set) as a parameter. The nice side > effect of this is that cgroup_task_migrate is now identical for > cgroup_attach_task and cgroup_attach_proc. It also now returns a > void since it can never fail. > > Changes in V4: > * https://lkml.org/lkml/2011/12/22/421 (Li Zefan) > * Avoid GFP_KERNEL (sleep) in rcu_read_lock by getting css_set in > a separate loop not under an rcu_read_lock > Changes in V3: > * https://lkml.org/lkml/2011/12/22/13 (Li Zefan) > * Fixed earlier bug by creating a seperate patch to remove tasklist_lock > Changes in V2: > * https://lkml.org/lkml/2011/12/20/372 (Tejun Heo) > * Move find_css_set call into loop which creates the flex array > * Author > * Kill css_set_refs and use group_size instead > * Fix an off-by-one error in counting css_set refs > * Add a retval check in out_list_teardown > > Signed-off-by: Mandeep Singh Baines Acked-by: Li Zefan > Cc: Tejun Heo > Cc: Li Zefan > Cc: containers@lists.linux-foundation.org > Cc: cgroups@vger.kernel.org > Cc: KAMEZAWA Hiroyuki > Cc: Frederic Weisbecker > Cc: Oleg Nesterov > Cc: Andrew Morton > Cc: Paul Menage > --- > kernel/cgroup.c | 142 +++++++++++------------------------------------------- > 1 files changed, 29 insertions(+), 113 deletions(-)