From mboxrd@z Thu Jan 1 00:00:00 1970 From: Wu Fengguang Subject: Re: [PATCH 3/5] writeback: dirty rate control Date: Mon, 15 Aug 2011 22:11:38 +0800 Message-ID: <20110815141138.GB23601@localhost> References: <20110806084447.388624428@intel.com> <20110806094526.878435971@intel.com> <20110809155046.GD6482@redhat.com> <1312906591.1083.43.camel@twins> <20110810140002.GA29724@localhost> <1312996226.23660.43.camel@twins> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Vivek Goyal , "linux-fsdevel@vger.kernel.org" , Andrew Morton , Jan Kara , Christoph Hellwig , Dave Chinner , Greg Thelen , Minchan Kim , Andrea Righi , linux-mm , LKML To: Peter Zijlstra Return-path: Content-Disposition: inline In-Reply-To: <1312996226.23660.43.camel@twins> Sender: owner-linux-mm@kvack.org List-Id: linux-fsdevel.vger.kernel.org On Thu, Aug 11, 2011 at 01:10:26AM +0800, Peter Zijlstra wrote: > On Wed, 2011-08-10 at 22:00 +0800, Wu Fengguang wrote: > > > > > Although I'm not quite sure how he keeps fairness in light of the > > > sleep time bounding to MAX_PAUSE. > > > > Firstly, MAX_PAUSE will only be applied when the dirty pages rush > > high (dirty exceeded). Secondly, the dirty exceeded state is global > > to all tasks, in which case each task will sleep for MAX_PAUSE equally. > > So the fairness is still maintained in dirty exceeded state. > > Its not immediately apparent how dirty_exceeded and MAX_PAUSE interact, > but having everybody sleep MAX_PAUSE doesn't necessarily mean its fair, > its only fair if they dirty at the same rate. Yeah I forget to mention that, but when dirty_exceeded, the tasks will typically sleep for MAX_PAUSE on every 8 pages, so resulting in the same dirty rate :) Thanks, Fengguang -- 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