From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754198Ab1HJRLD (ORCPT ); Wed, 10 Aug 2011 13:11:03 -0400 Received: from merlin.infradead.org ([205.233.59.134]:60321 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752409Ab1HJRLC convert rfc822-to-8bit (ORCPT ); Wed, 10 Aug 2011 13:11:02 -0400 Subject: Re: [PATCH 3/5] writeback: dirty rate control From: Peter Zijlstra To: Wu Fengguang 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 Date: Wed, 10 Aug 2011 19:10:26 +0200 In-Reply-To: <20110810140002.GA29724@localhost> References: <20110806084447.388624428@intel.com> <20110806094526.878435971@intel.com> <20110809155046.GD6482@redhat.com> <1312906591.1083.43.camel@twins> <20110810140002.GA29724@localhost> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8BIT X-Mailer: Evolution 3.0.2- Message-ID: <1312996226.23660.43.camel@twins> Mime-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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. From mboxrd@z Thu Jan 1 00:00:00 1970 From: Peter Zijlstra Subject: Re: [PATCH 3/5] writeback: dirty rate control Date: Wed, 10 Aug 2011 19:10:26 +0200 Message-ID: <1312996226.23660.43.camel@twins> References: <20110806084447.388624428@intel.com> <20110806094526.878435971@intel.com> <20110809155046.GD6482@redhat.com> <1312906591.1083.43.camel@twins> <20110810140002.GA29724@localhost> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable 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: Wu Fengguang Return-path: In-Reply-To: <20110810140002.GA29724@localhost> Sender: owner-linux-mm@kvack.org List-Id: linux-fsdevel.vger.kernel.org On Wed, 2011-08-10 at 22:00 +0800, Wu Fengguang wrote: >=20 > > Although I'm not quite sure how he keeps fairness in light of the > > sleep time bounding to MAX_PAUSE. >=20 > 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.=20 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. -- 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