From mboxrd@z Thu Jan 1 00:00:00 1970 From: Glauber Costa Subject: Re: [PATCH v3 13/28] slub: create duplicate cache Date: Tue, 29 May 2012 21:27:02 +0400 Message-ID: <4FC506E6.8030108@parallels.com> References: <1337951028-3427-1-git-send-email-glommer@parallels.com> <1337951028-3427-14-git-send-email-glommer@parallels.com> <4FC4F1A7.2010206@parallels.com> <4FC501E9.60607@parallels.com> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Sender: cgroups-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-ID: Content-Type: text/plain; charset="us-ascii"; format="flowed" To: Christoph Lameter Cc: linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org, kamezawa.hiroyu-+CUm20s59erQFUHtdCDX3A@public.gmane.org, Tejun Heo , Li Zefan , Greg Thelen , Suleiman Souhlal , Michal Hocko , Johannes Weiner , devel-GEFAQzZX7r8dnm+yROfE0A@public.gmane.org, David Rientjes , Pekka Enberg On 05/29/2012 09:25 PM, Christoph Lameter wrote: >> I will try to at least have the page accounting done in a consistent way. How >> > about that? > Ok. What do you mean by "consistent"? Since objects and pages can be used > in a shared way and since accounting in many areas of the kernel is > intentional fuzzy to avoid performance issues there is not that much of a > requirement for accuracy. We have problems even just defining what the > exact set of pages belonging to a task/process is. > I mean consistent between allocators, done in a shared place. Note that what we do here *is* still fuzzy to some degree. We can have a level of sharing, and always account to the first one to touch, we don't go worrying about this because that would be hell. We also don't carry a process' objects around when we send it to a different cgroup. Those are all already simplications for performance and simplicity sake. But we really need a page to be filled with objects from the same cgroup, and the non-shared objects to be accounted to the right place. Otherwise, I don't think we can meet even the lighter of isolation guarantees. From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx195.postini.com [74.125.245.195]) by kanga.kvack.org (Postfix) with SMTP id 116E46B005D for ; Tue, 29 May 2012 13:29:24 -0400 (EDT) Message-ID: <4FC506E6.8030108@parallels.com> Date: Tue, 29 May 2012 21:27:02 +0400 From: Glauber Costa MIME-Version: 1.0 Subject: Re: [PATCH v3 13/28] slub: create duplicate cache References: <1337951028-3427-1-git-send-email-glommer@parallels.com> <1337951028-3427-14-git-send-email-glommer@parallels.com> <4FC4F1A7.2010206@parallels.com> <4FC501E9.60607@parallels.com> In-Reply-To: Content-Type: text/plain; charset="ISO-8859-1"; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Christoph Lameter Cc: linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, linux-mm@kvack.org, kamezawa.hiroyu@jp.fujitsu.com, Tejun Heo , Li Zefan , Greg Thelen , Suleiman Souhlal , Michal Hocko , Johannes Weiner , devel@openvz.org, David Rientjes , Pekka Enberg On 05/29/2012 09:25 PM, Christoph Lameter wrote: >> I will try to at least have the page accounting done in a consistent way. How >> > about that? > Ok. What do you mean by "consistent"? Since objects and pages can be used > in a shared way and since accounting in many areas of the kernel is > intentional fuzzy to avoid performance issues there is not that much of a > requirement for accuracy. We have problems even just defining what the > exact set of pages belonging to a task/process is. > I mean consistent between allocators, done in a shared place. Note that what we do here *is* still fuzzy to some degree. We can have a level of sharing, and always account to the first one to touch, we don't go worrying about this because that would be hell. We also don't carry a process' objects around when we send it to a different cgroup. Those are all already simplications for performance and simplicity sake. But we really need a page to be filled with objects from the same cgroup, and the non-shared objects to be accounted to the right place. Otherwise, I don't think we can meet even the lighter of isolation guarantees. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754689Ab2E2R3Y (ORCPT ); Tue, 29 May 2012 13:29:24 -0400 Received: from mx2.parallels.com ([64.131.90.16]:60983 "EHLO mx2.parallels.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754088Ab2E2R3W (ORCPT ); Tue, 29 May 2012 13:29:22 -0400 Message-ID: <4FC506E6.8030108@parallels.com> Date: Tue, 29 May 2012 21:27:02 +0400 From: Glauber Costa User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:10.0.1) Gecko/20120216 Thunderbird/10.0.1 MIME-Version: 1.0 To: Christoph Lameter CC: , , , , Tejun Heo , Li Zefan , Greg Thelen , Suleiman Souhlal , Michal Hocko , Johannes Weiner , , David Rientjes , Pekka Enberg Subject: Re: [PATCH v3 13/28] slub: create duplicate cache References: <1337951028-3427-1-git-send-email-glommer@parallels.com> <1337951028-3427-14-git-send-email-glommer@parallels.com> <4FC4F1A7.2010206@parallels.com> <4FC501E9.60607@parallels.com> In-Reply-To: Content-Type: text/plain; charset="ISO-8859-1"; format=flowed Content-Transfer-Encoding: 7bit X-Originating-IP: [188.255.67.70] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 05/29/2012 09:25 PM, Christoph Lameter wrote: >> I will try to at least have the page accounting done in a consistent way. How >> > about that? > Ok. What do you mean by "consistent"? Since objects and pages can be used > in a shared way and since accounting in many areas of the kernel is > intentional fuzzy to avoid performance issues there is not that much of a > requirement for accuracy. We have problems even just defining what the > exact set of pages belonging to a task/process is. > I mean consistent between allocators, done in a shared place. Note that what we do here *is* still fuzzy to some degree. We can have a level of sharing, and always account to the first one to touch, we don't go worrying about this because that would be hell. We also don't carry a process' objects around when we send it to a different cgroup. Those are all already simplications for performance and simplicity sake. But we really need a page to be filled with objects from the same cgroup, and the non-shared objects to be accounted to the right place. Otherwise, I don't think we can meet even the lighter of isolation guarantees.