From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tejun Heo Subject: Re: [RFC] writeback and cgroup Date: Thu, 5 Apr 2012 09:31:13 -0700 Message-ID: <20120405163113.GD12854__1202.47658710486$1333643490$gmane$org@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-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <20120404201816.GL12676-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: containers-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org Errors-To: containers-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org To: Vivek Goyal Cc: Jens Axboe , ctalbott-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org, Jan Kara , rni-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org, andrea-oIIqvOZpAevzfdHfmsDf5w@public.gmane.org, containers-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, sjayaraman-IBi9RG/b67k@public.gmane.org, lsf-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org, linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org, jmoyer-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org, linux-fsdevel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Fengguang Wu List-Id: containers.vger.kernel.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