From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758076Ab2IZR4m (ORCPT ); Wed, 26 Sep 2012 13:56:42 -0400 Received: from mx2.parallels.com ([64.131.90.16]:43594 "EHLO mx2.parallels.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758016Ab2IZR4k (ORCPT ); Wed, 26 Sep 2012 13:56:40 -0400 Message-ID: <50634105.8060302@parallels.com> Date: Wed, 26 Sep 2012 21:53:09 +0400 From: Glauber Costa User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:15.0) Gecko/20120911 Thunderbird/15.0.1 MIME-Version: 1.0 To: Tejun Heo CC: Michal Hocko , , , , , , Suleiman Souhlal , Frederic Weisbecker , Mel Gorman , David Rientjes , Johannes Weiner Subject: Re: [PATCH v3 04/13] kmem accounting basic infrastructure References: <1347977050-29476-1-git-send-email-glommer@parallels.com> <1347977050-29476-5-git-send-email-glommer@parallels.com> <20120926140347.GD15801@dhcp22.suse.cz> <20120926163648.GO16296@google.com> <50633D24.6020002@parallels.com> In-Reply-To: Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 7bit X-Originating-IP: [109.173.3.27] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 09/26/2012 09:44 PM, Tejun Heo wrote: > Hello, Glauber. > > On Wed, Sep 26, 2012 at 10:36 AM, Glauber Costa wrote: >> This was discussed multiple times. Our interest is to preserve existing >> deployed setup, that were tuned in a world where kmem didn't exist. >> Because we also feed kmem to the user counter, this may very well >> disrupt their setup. > > So, that can be served by .kmem_accounted at root, no? > >> User memory, unlike kernel memory, may very well be totally in control >> of the userspace application, so it is not unreasonable to believe that >> extra pages appearing in a new kernel version may break them. >> >> It is actually a much worse compatibility problem than flipping >> hierarchy, in comparison > > Again, what's wrong with one switch at the root? > I understand your trauma about over flexibility, and you know I share of it. But I don't think there is any need to cap it here. Given kmem accounted is perfectly hierarchical, and there seem to be plenty of people who only care about user memory, I see no reason to disallow a mixed use case here. I must say that for my particular use case, enabling it unconditionally would just work, so it is not that what I have in mind. From mboxrd@z Thu Jan 1 00:00:00 1970 From: Glauber Costa Subject: Re: [PATCH v3 04/13] kmem accounting basic infrastructure Date: Wed, 26 Sep 2012 21:53:09 +0400 Message-ID: <50634105.8060302@parallels.com> References: <1347977050-29476-1-git-send-email-glommer@parallels.com> <1347977050-29476-5-git-send-email-glommer@parallels.com> <20120926140347.GD15801@dhcp22.suse.cz> <20120926163648.GO16296@google.com> <50633D24.6020002@parallels.com> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Sender: owner-linux-mm@kvack.org List-ID: Content-Type: text/plain; charset="us-ascii" To: Tejun Heo Cc: Michal Hocko , linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, kamezawa.hiroyu@jp.fujitsu.com, devel@openvz.org, linux-mm@kvack.org, Suleiman Souhlal , Frederic Weisbecker , Mel Gorman , David Rientjes , Johannes Weiner On 09/26/2012 09:44 PM, Tejun Heo wrote: > Hello, Glauber. > > On Wed, Sep 26, 2012 at 10:36 AM, Glauber Costa wrote: >> This was discussed multiple times. Our interest is to preserve existing >> deployed setup, that were tuned in a world where kmem didn't exist. >> Because we also feed kmem to the user counter, this may very well >> disrupt their setup. > > So, that can be served by .kmem_accounted at root, no? > >> User memory, unlike kernel memory, may very well be totally in control >> of the userspace application, so it is not unreasonable to believe that >> extra pages appearing in a new kernel version may break them. >> >> It is actually a much worse compatibility problem than flipping >> hierarchy, in comparison > > Again, what's wrong with one switch at the root? > I understand your trauma about over flexibility, and you know I share of it. But I don't think there is any need to cap it here. Given kmem accounted is perfectly hierarchical, and there seem to be plenty of people who only care about user memory, I see no reason to disallow a mixed use case here. I must say that for my particular use case, enabling it unconditionally would just work, so it is not that what I have in mind. -- 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/ . Don't email: email@kvack.org