From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753946Ab1HKVAd (ORCPT ); Thu, 11 Aug 2011 17:00:33 -0400 Received: from mx1.redhat.com ([209.132.183.28]:21805 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753718Ab1HKVAc (ORCPT ); Thu, 11 Aug 2011 17:00:32 -0400 Date: Thu, 11 Aug 2011 17:00:08 -0400 From: Vivek Goyal To: Wu Fengguang Cc: "linux-fsdevel@vger.kernel.org" , Andrew Morton , Jan Kara , Christoph Hellwig , Dave Chinner , Greg Thelen , Minchan Kim , Andrea Righi , linux-mm , LKML Subject: Re: [PATCH 0/5] IO-less dirty throttling v8 Message-ID: <20110811210008.GI8552@redhat.com> References: <20110806084447.388624428@intel.com> <20110809020127.GA3700@redhat.com> <20110811032143.GB11404@localhost> <20110811204255.GH8552@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20110811204255.GH8552@redhat.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Aug 11, 2011 at 04:42:55PM -0400, Vivek Goyal wrote: [..] > So I see following immediate extension of your scheme possible. > > - Inherit ioprio from iocontext and provide buffered write service > differentiation for writers. > > - Create a per task buffered write throttling interface and do > absolute throttling of task. > > - We can possibly do the idea of throttling group wide buffered > writes only control at this layer using this mechanism. Though personally I like the idea of absolute throttling at page cache level as it can help a bit with problem of buffered WRITES impacting the latency of everything else in the system. CFQ helps a lot but it idles enough that cost of this isolation is very high on faster storage. Deadline and noop really do not do much about protection from WRITEs. So it is not perfect but might prove to be good enough for some use cases. Thanks Vivek