From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752253Ab2A3G57 (ORCPT ); Mon, 30 Jan 2012 01:57:59 -0500 Received: from cn.fujitsu.com ([222.73.24.84]:62047 "EHLO song.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1750996Ab2A3G55 (ORCPT ); Mon, 30 Jan 2012 01:57:57 -0500 Message-ID: <4F264013.1040603@cn.fujitsu.com> Date: Mon, 30 Jan 2012 15:00:35 +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 , linux-kernel@vger.kernel.org, Frederic Weisbecker , containers@lists.linux-foundation.org, cgroups@vger.kernel.org, KAMEZAWA Hiroyuki , Oleg Nesterov , Andrew Morton , Paul Menage Subject: Re: [PATCH] cgroup: remove extra calls to find_existing_css_set References: <1327429591-8507-1-git-send-email-msb@chromium.org> In-Reply-To: <1327429591-8507-1-git-send-email-msb@chromium.org> X-MIMETrack: Itemize by SMTP Server on mailserver/fnst(Release 8.5.1FP4|July 25, 2010) at 2012-01-30 14:56:32, Serialize by Router on mailserver/fnst(Release 8.5.1FP4|July 25, 2010) at 2012-01-30 14:56:35, Serialize complete at 2012-01-30 14:56:35 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 V5: > * https://lkml.org/lkml/2012/1/20/344 (Tejun Heo) > * Remove css_set_refs > 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 Please add my ack in your changelog when you update the patch. > 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 | 143 +++++++++++-------------------------------------------- > 1 files changed, 28 insertions(+), 115 deletions(-)