From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx200.postini.com [74.125.245.200]) by kanga.kvack.org (Postfix) with SMTP id 5218D6B004D for ; Tue, 24 Apr 2012 18:54:24 -0400 (EDT) Received: by iajr24 with SMTP id r24so2287173iaj.14 for ; Tue, 24 Apr 2012 15:54:23 -0700 (PDT) Date: Tue, 24 Apr 2012 15:54:20 -0700 (PDT) From: David Rientjes Subject: Re: [PATCH 17/23] kmem controller charge/uncharge infrastructure In-Reply-To: <4F971CC2.3090109@parallels.com> Message-ID: References: <1334959051-18203-1-git-send-email-glommer@parallels.com> <1335138820-26590-6-git-send-email-glommer@parallels.com> <20120424142232.GC8626@somewhere> <4F96BB62.1030900@parallels.com> <4F971CC2.3090109@parallels.com> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org List-ID: To: Glauber Costa Cc: Frederic Weisbecker , cgroups@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, devel@openvz.org, KAMEZAWA Hiroyuki , Michal Hocko , Johannes Weiner , Greg Thelen , Suleiman Souhlal , Christoph Lameter , Pekka Enberg On Tue, 24 Apr 2012, Glauber Costa wrote: > > Yes, for user memory, I see charging to p->mm->owner as allowing that > > process to eventually move and be charged to a different memcg and there's > > no way to do proper accounting if the charge is split amongst different > > memcgs because of thread membership to a set of memcgs. This is > > consistent with charges for shared memory being moved when a thread > > mapping it moves to a new memcg, as well. > > But that's the problem. > > When we are dealing with kernel memory, we are allocating a whole slab page. > It is essentially impossible to track, given a page, which task allocated > which object. > Right, so you have to make the distinction that slab charges cannot be migrated by memory.move_charge_at_immigrate (and it's not even specified to do anything beyond user pages in Documentation/cgroups/memory.txt), but it would be consistent to charge the same memcg for a process's slab allocations as the process's user allocations. My response was why we shouldn't be charging user pages to mem_cgroup_from_task(current) rather than mem_cgroup_from_task(current->mm->owner) which is what is currently implemented. If that can't be changed so that we can still migrate user memory amongst memcgs for memory.move_charge_at_immigrate, then it seems consistent to have all allocations done by a task to be charged to the same memcg. Hence, I suggested current->mm->owner for slab charging as well. -- 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