Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752446Ab1FGJDj (ORCPT ); Tue, 7 Jun 2011 05:03:39 -0400 Received: from fgwmail6.fujitsu.co.jp ([192.51.44.36]:36271 "EHLO fgwmail6.fujitsu.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751803Ab1FGJDh (ORCPT ); Tue, 7 Jun 2011 05:03:37 -0400 X-SecurityPolicyCheck-FJ: OK by FujitsuOutboundMailChecker v1.3.1 Date: Tue, 7 Jun 2011 17:56:34 +0900 From: KAMEZAWA Hiroyuki To: Greg Thelen Cc: Andrew Morton , linux-kernel@vger.kernel.org, linux-mm@kvack.org, containers@lists.osdl.org, linux-fsdevel@vger.kernel.org, Andrea Righi , Balbir Singh , Daisuke Nishimura , Minchan Kim , Johannes Weiner , Ciju Rajan K , David Rientjes , Wu Fengguang , Vivek Goyal , Dave Chinner Subject: Re: [PATCH v8 11/12] writeback: make background writeback cgroup aware Message-Id: <20110607175634.b07f2e57.kamezawa.hiroyu@jp.fujitsu.com> In-Reply-To: <1307117538-14317-12-git-send-email-gthelen@google.com> References: <1307117538-14317-1-git-send-email-gthelen@google.com> <1307117538-14317-12-git-send-email-gthelen@google.com> Organization: FUJITSU Co. LTD. X-Mailer: Sylpheed 3.1.0 (GTK+ 2.10.14; i686-pc-mingw32) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2156 Lines: 47 On Fri, 3 Jun 2011 09:12:17 -0700 Greg Thelen wrote: > When the system is under background dirty memory threshold but a cgroup > is over its background dirty memory threshold, then only writeback > inodes associated with the over-limit cgroup(s). > > In addition to checking if the system dirty memory usage is over the > system background threshold, over_bground_thresh() also checks if any > cgroups are over their respective background dirty memory thresholds. > The writeback_control.for_cgroup field is set to distinguish between a > system and memcg overage. > > If performing cgroup writeback, move_expired_inodes() skips inodes that > do not contribute dirty pages to the cgroup being written back. > > After writing some pages, wb_writeback() will call > mem_cgroup_writeback_done() to update the set of over-bg-limits memcg. > > Signed-off-by: Greg Thelen > --- > Changelog since v7: > - over_bground_thresh() now sets shared_inodes=1. In -v7 per memcg > background writeback did not, so it did not write pages of shared > inodes in background writeback. In the (potentially common) case > where the system dirty memory usage is below the system background > dirty threshold but at least one cgroup is over its background dirty > limit, then per memcg background writeback is queued for any > over-background-threshold cgroups. Background writeback should be > allowed to writeback shared inodes. The hope is that writing such > inodes has good chance of cleaning the inodes so they can transition > from shared to non-shared. Such a transition is good because then the > inode will remain unshared until it is written by multiple cgroup. > Non-shared inodes offer better isolation. If you post v9, please adds above explanation as the comments in the code. Acked-by: KAMEZAWA Hiroyuki -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/