From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965513AbXDCRK5 (ORCPT ); Tue, 3 Apr 2007 13:10:57 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S965687AbXDCRK5 (ORCPT ); Tue, 3 Apr 2007 13:10:57 -0400 Received: from smtp-out.google.com ([216.239.33.17]:26814 "EHLO smtp-out.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965663AbXDCRK4 (ORCPT ); Tue, 3 Apr 2007 13:10:56 -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=cblzRXY3+scBtJFzDWeR90RaPmgVOih5XbZ5J7NBFU67xjpMjo3/UidKN119VFiT+ yAX/WnRWx40IoZ8Fax9xw== Message-ID: <6599ad830704031010i5418abf1o12b11334cde4d2c5@mail.gmail.com> Date: Tue, 3 Apr 2007 10:10:35 -0700 From: "Paul Menage" To: vatsa@in.ibm.com Subject: Re: [ckrm-tech] [PATCH 7/7] containers (V7): Container interface to nsproxy subsystem Cc: sekharan@us.ibm.com, ckrm-tech@lists.sourceforge.net, linux-kernel@vger.kernel.org, xemul@sw.ru, dev@sw.ru, rohitseth@google.com, pj@sgi.com, "Eric W. Biederman" , mbligh@google.com, winget@google.com, containers@lists.osdl.org, "Serge E. Hallyn" , devel@openvz.org In-Reply-To: <20070403171155.GK2456@in.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Content-Disposition: inline References: <20070212081521.808338000@menage.corp.google.com> <20070331024722.GA808@in.ibm.com> <20070402140938.GF17710@sergelap.austin.ibm.com> <20070402142727.GF2456@in.ibm.com> <20070403153220.GA24946@sergelap.austin.ibm.com> <6599ad830704030845p654cf8dh65ccdc46c92d3688@mail.gmail.com> <20070403164615.GJ2456@in.ibm.com> <6599ad830704030952r5c295f3ap6e366de31dab2ccb@mail.gmail.com> <20070403171155.GK2456@in.ibm.com> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On 4/3/07, Srivatsa Vaddagiri wrote: > On Tue, Apr 03, 2007 at 09:52:35AM -0700, Paul Menage wrote: > > I'm not saying "let's use nsproxy" - I'm not yet convinced that the > > lifetime/mutation/correlation rate of a pointer in an nsproxy is > > likely to be the same as for a container subsystem; if not, then > > reusing nsproxy could actually increase space overheads (since you'd > > end up with more, larger nsproxy objects, compared to smaller numbers > > of smaller nsproxy objects and smaller numbers of smaller > > container_group objects), even though it saved (just) one pointer per > > task_struct. > > Even if nsproxy objects are made larger a bit, the number of such object will You're not making them "a bit" larger, you're adding N+M pointers where N is the number of container hierarchies and M is the number of subsystem slots. Basically, it means that anyone that uses containers without namespaces or vice versa ends up paying the space overheads for both. > be -much- lesser compared to number of task_structs I would think, so > the win/lose in space savings would need to take that into account. Agreed. So I'm not saying it's fundamentally a bad idea - just that merging container_group and nsproxy is a fairly simple space optimization that could easily be done later. Paul