From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx153.postini.com [74.125.245.153]) by kanga.kvack.org (Postfix) with SMTP id 079896B004A for ; Thu, 5 Apr 2012 12:31:19 -0400 (EDT) Received: by iajr24 with SMTP id r24so2727971iaj.14 for ; Thu, 05 Apr 2012 09:31:19 -0700 (PDT) Date: Thu, 5 Apr 2012 09:31:13 -0700 From: Tejun Heo Subject: Re: [RFC] writeback and cgroup Message-ID: <20120405163113.GD12854@google.com> References: <20120403183655.GA23106@dhcp-172-17-108-109.mtv.corp.google.com> <20120404175124.GA8931@localhost> <20120404193355.GD29686@dhcp-172-17-108-109.mtv.corp.google.com> <20120404201816.GL12676@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20120404201816.GL12676@redhat.com> Sender: owner-linux-mm@kvack.org List-ID: To: Vivek Goyal Cc: Fengguang Wu , Jan Kara , Jens Axboe , linux-mm@kvack.org, sjayaraman@suse.com, andrea@betterlinux.com, jmoyer@redhat.com, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, kamezawa.hiroyu@jp.fujitsu.com, lizefan@huawei.com, containers@lists.linux-foundation.org, cgroups@vger.kernel.org, ctalbott@google.com, rni@google.com, lsf@lists.linux-foundation.org Hey, Vivek. On Wed, Apr 04, 2012 at 04:18:16PM -0400, Vivek Goyal wrote: > Hey how about reconsidering my other proposal for which I had posted > the patches. And that is keep throttling still at device level. Reads > and direct IO get throttled asynchronously but buffered writes get > throttled synchronously. > > Advantages of this scheme. > > - There are no separate knobs. > > - All the IO (read, direct IO and buffered write) is controlled using > same set of knobs and goes in queue of same cgroup. > > - Writeback logic has no knowledge of throttling. It just invokes a > hook into throttling logic of device queue. > > I guess this is a hybrid of active writeback throttling and back pressure > mechanism. > > But it still does not solve the NFS issue as well as for direct IO, > filesystems still can get serialized, so metadata issue still needs to > be resolved. So one can argue that why not go for full "back pressure" > method, despite it being more complex. > > Here is the link, just to refresh the memory. Something to keep in mind > while assessing alternatives. > > https://lkml.org/lkml/2011/6/28/243 Hmmm... so, this only works for blk-throttle and not with the weight. How do you manage interaction between buffered writes and direct writes for the same cgroup? Thanks. -- tejun -- 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