From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752648AbXCZNaf (ORCPT ); Mon, 26 Mar 2007 09:30:35 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752659AbXCZNaf (ORCPT ); Mon, 26 Mar 2007 09:30:35 -0400 Received: from amsfep15-int.chello.nl ([62.179.120.10]:60763 "EHLO amsfep15-int.chello.nl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752648AbXCZNae (ORCPT ); Mon, 26 Mar 2007 09:30:34 -0400 Subject: Re: [patch 1/3] fix illogical behavior in balance_dirty_pages() From: Peter Zijlstra To: Andrew Morton Cc: Miklos Szeredi , dgc@sgi.com, linux-kernel@vger.kernel.org In-Reply-To: <20070326020823.8630bb07.akpm@linux-foundation.org> References: <20070325153508.10922ebd.akpm@linux-foundation.org> <20070326010124.b4513ce2.akpm@linux-foundation.org> <20070326020823.8630bb07.akpm@linux-foundation.org> Content-Type: text/plain Date: Mon, 26 Mar 2007 15:30:27 +0200 Message-Id: <1174915828.6792.31.camel@twins> Mime-Version: 1.0 X-Mailer: Evolution 2.9.92 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 2007-03-26 at 02:08 -0800, Andrew Morton wrote: > On Mon, 26 Mar 2007 11:32:47 +0200 Miklos Szeredi wrote: > > > Stopping writers which have idle queues is completely unproductive, > > and that is basically what the current algorithm does. > > This is because the kernel permits all of its allotment of dirty+writeback > pages to be dirty+writeback against a single device. > > A good way of solving the one-device-starves-another-one problem is to > dynamically adjust the per-device dirty+writeback levels so that (for > example) if two devices are being written to, each gets 50% of the > allotment. This is exactly what happens with my patch if both devices write at the same speed. (Or at least, that is what is supposed to happen ;-)