From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wi0-f177.google.com (mail-wi0-f177.google.com [209.85.212.177]) by kanga.kvack.org (Postfix) with ESMTP id 98B036B0035 for ; Tue, 5 Aug 2014 09:34:51 -0400 (EDT) Received: by mail-wi0-f177.google.com with SMTP id ho1so1351801wib.10 for ; Tue, 05 Aug 2014 06:34:49 -0700 (PDT) Received: from mx2.suse.de (cantor2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id t8si4739351wia.13.2014.08.05.06.34.38 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Tue, 05 Aug 2014 06:34:38 -0700 (PDT) Date: Tue, 5 Aug 2014 15:34:28 +0200 From: Michal Hocko Subject: Re: [patch] mm: memcontrol: avoid charge statistics churn during page migration Message-ID: <20140805133428.GH15908@dhcp22.suse.cz> References: <1407184469-20741-1-git-send-email-hannes@cmpxchg.org> <20140805122434.GD15908@dhcp22.suse.cz> <20140805131223.GA14734@cmpxchg.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20140805131223.GA14734@cmpxchg.org> Sender: owner-linux-mm@kvack.org List-ID: To: Johannes Weiner Cc: Andrew Morton , Hugh Dickins , linux-mm@kvack.org, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org On Tue 05-08-14 09:12:23, Johannes Weiner wrote: > On Tue, Aug 05, 2014 at 02:24:34PM +0200, Michal Hocko wrote: > > On Mon 04-08-14 16:34:29, Johannes Weiner wrote: > > > Charge migration currently disables IRQs twice to update the charge > > > statistics for the old page and then again for the new page. > > > > > > But migration is a seemless transition of a charge from one physical > > > page to another one of the same size, so this should be a non-event > > > from an accounting point of view. Leave the statistics alone. > > > > Moving stats to mem_cgroup_commit_charge sounds logical to me but does > > this work properly even for the fuse replace page cache case when old > > and new pages can already live in different memcgs? > > We don't migrate if the new page is already charged. Right you are. Acked-by: Michal Hocko -- Michal Hocko SUSE Labs -- 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