Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751641Ab0HTF43 (ORCPT ); Fri, 20 Aug 2010 01:56:29 -0400 Received: from mga03.intel.com ([143.182.124.21]:31936 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751288Ab0HTF40 (ORCPT ); Fri, 20 Aug 2010 01:56:26 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.56,238,1280732400"; d="scan'208";a="314886613" Date: Fri, 20 Aug 2010 13:56:21 +0800 From: Wu Fengguang To: Con Kolivas Cc: KOSAKI Motohiro , Andrew Morton , "linux-kernel@vger.kernel.org" , "linux-fsdevel@vger.kernel.org" , "linux-mm@kvack.org" , "riel@redhat.com" , "david@fromorbit.com" , "hch@lst.de" , "axboe@kernel.dk" Subject: Re: [PATCH] writeback: remove the internal 5% low bound on dirty_ratio Message-ID: <20100820055621.GA14110@localhost> References: <20100820032506.GA6662@localhost> <20100820131249.5FF4.A69D9226@jp.fujitsu.com> <201008201550.54164.kernel@kolivas.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <201008201550.54164.kernel@kolivas.org> User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1470 Lines: 33 On Fri, Aug 20, 2010 at 01:50:54PM +0800, Con Kolivas wrote: > On Fri, 20 Aug 2010 02:13:25 pm KOSAKI Motohiro wrote: > > > The dirty_ratio was silently limited to >= 5%. This is not a user > > > expected behavior. Let's rip it. > > > > > > It's not likely the user space will depend on the old behavior. > > > So the risk of breaking user space is very low. > > > > > > CC: Jan Kara > > > CC: Neil Brown > > > Signed-off-by: Wu Fengguang > > > > Thank you. > > Reviewed-by: KOSAKI Motohiro > > I have tried to do this in the past, and setting this value to 0 on some > machines caused the machine to come to a complete standstill with small > writes to disk. It seemed there was some kind of "minimum" amount of data > required by the VM before anything would make it to the disk and I never > quite found out where that blockade occurred. This was some time ago (3 years > ago) so I'm not sure if the problem has since been fixed in the VM since > then. I suggest you do some testing with this value set to zero before > approving this change. Good point. I'll do more homework. Thanks for the reminding! Thanks, Fengguang -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/