From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754338AbaIVR2H (ORCPT ); Mon, 22 Sep 2014 13:28:07 -0400 Received: from mail-we0-f172.google.com ([74.125.82.172]:64079 "EHLO mail-we0-f172.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753958AbaIVR2F (ORCPT ); Mon, 22 Sep 2014 13:28:05 -0400 Date: Mon, 22 Sep 2014 19:28:00 +0200 From: Michal Hocko To: Johannes Weiner Cc: linux-mm@kvack.org, Greg Thelen , Dave Hansen , cgroups@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [patch] mm: memcontrol: lockless page counters Message-ID: <20140922172800.GA4343@dhcp22.suse.cz> References: <1411132928-16143-1-git-send-email-hannes@cmpxchg.org> <20140922144436.GG336@dhcp22.suse.cz> <20140922155049.GA6630@cmpxchg.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20140922155049.GA6630@cmpxchg.org> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon 22-09-14 11:50:49, Johannes Weiner wrote: > On Mon, Sep 22, 2014 at 04:44:36PM +0200, Michal Hocko wrote: > > On Fri 19-09-14 09:22:08, Johannes Weiner wrote: [...] > > Nevertheless I think that the counter should live outside of memcg (it > > is ugly and bad in general to make HUGETLB controller depend on MEMCG > > just to have a counter). If you made kernel/page_counter.c and led both > > containers select CONFIG_PAGE_COUNTER then you do not need a dependency > > on MEMCG and I would find it cleaner in general. > > The reason I did it this way is because the hugetlb controller simply > accounts and limits a certain type of memory and in the future I would > like to make it a memcg extension, just like kmem and swap. I am not sure this is the right way to go. Hugetlb has always been "special" and I do not see any advantage to pull its specialness into memcg proper. It would just make the code more complicated. I can also imagine users who simply do not want to pay memcg overhead and use only hugetlb controller. Besides that it is not like a separate page_counter with a clear interface would cause more maintenance overhead so I really do not see any reason to pull it into memcg. -- Michal Hocko SUSE Labs