From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754451AbYDER5W (ORCPT ); Sat, 5 Apr 2008 13:57:22 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752823AbYDER5P (ORCPT ); Sat, 5 Apr 2008 13:57:15 -0400 Received: from smtp-out.google.com ([216.239.33.17]:11214 "EHLO smtp-out.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752655AbYDER5O (ORCPT ); Sat, 5 Apr 2008 13:57:14 -0400 DomainKey-Signature: a=rsa-sha1; s=beta; d=google.com; c=nofws; q=dns; h=received:message-id:date:from:to:subject:cc:in-reply-to: mime-version:content-type:content-transfer-encoding: content-disposition:references; b=ymW6/lyhg7+4bunDKg3KZzKnRSVAdU27KlELU4uIqAO5EHFJF9hLxaBHMhYFqi55l RHdREV215MRZh5F79TbIA== Message-ID: <6599ad830804051057n2f2802e4w6179f2e108467494@mail.gmail.com> Date: Sat, 5 Apr 2008 10:57:00 -0700 From: "Paul Menage" To: balbir@linux.vnet.ibm.com Subject: Re: [-mm] Add an owner to the mm_struct (v8) Cc: "Pavel Emelianov" , "Hugh Dickins" , "Sudhir Kumar" , "YAMAMOTO Takashi" , lizf@cn.fujitsu.com, linux-kernel@vger.kernel.org, taka@valinux.co.jp, linux-mm@kvack.org, "David Rientjes" , "Andrew Morton" , "KAMEZAWA Hiroyuki" In-Reply-To: <47F7BB69.3000502@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Content-Disposition: inline References: <20080404080544.26313.38199.sendpatchset@localhost.localdomain> <6599ad830804040112q3dd5333aodf6a170c78e61dc8@mail.gmail.com> <47F5E69C.9@linux.vnet.ibm.com> <6599ad830804040150j4946cf92h886bb26000319f3b@mail.gmail.com> <47F5F3FA.7060709@linux.vnet.ibm.com> <6599ad830804041211r37848a6coaa900d8bdac40fbe@mail.gmail.com> <47F79102.6090406@linux.vnet.ibm.com> <6599ad830804051023v69caa3d4h6e26ccb420bca899@mail.gmail.com> <47F7BB69.3000502@linux.vnet.ibm.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Apr 5, 2008 at 10:48 AM, Balbir Singh wrote: > Paul Menage wrote: > > On Sat, Apr 5, 2008 at 7:47 AM, Balbir Singh wrote: > >> Repeating my question earlier > >> > >> Can we delay setting task->cgroups = &init_css_set for the group_leader, until > >> all threads have exited? > > > > Potentially, yes. It also might make more sense to move the > > exit_cgroup() for all threads to a later point rather than special > > case delayed group leaders. > > > > Yes, that makes sense. I think that patch should be independent of this one > though? What do you think? Yes, it would probably need to be a separate patch. The current positioning of cgroup_exit() is more or less inherited from cpusets. I'd need to figure out if a change like that would break anything. > > > > Yes, I agree it could potentially happen. But it seems like a strange > > thing to do if you're planning to be not have the same groupings for > > cpu and va. > > It's easier to set it up that way. Usually the end user gets the same SLA for > memory, CPU and other resources, so it makes sense to bind the controllers together. > True - but in that case why wouldn't they have the same SLA for virtual address space too? > > >> I measured the overhead of removing the delay_group_leader optimization and > >> found a 4% impact on throughput (with volanomark, that is one of the > >> multi-threaded benchmarks I know of). > > > > Interesting, I thought (although I've never actually looked at the > > code) that volanomark was more of a scheduling benchmark than a > > process start/exit benchmark. How frequently does it have processes > > (not threads) exiting? > > > > I could not find any other interesting benchmark for benchmarking fork/exits. I > know that volanomark is heavily threaded, so I used it. The threads quickly exit > after processing the messages, I thought that would be a good test to see the > overhead. But surely the performance of thread exits wouldn't be affected by the delay_group_leader(p) change, since none of the exiting threads would be a group leader. That optimization only matters when the entire process exits. Does oprofile show any interesting differences? Paul