From mboxrd@z Thu Jan 1 00:00:00 1970 From: Peter Zijlstra Subject: Re: [PATCH 8/8] vm: Add an tuning knob for vm.max_writeback_pages Date: Wed, 02 Sep 2009 09:35:08 +0200 Message-ID: <1251876908.7547.54.camel@twins> References: <1251803946-9243-1-git-send-email-jens.axboe@oracle.com> <1251803946-9243-9-git-send-email-jens.axboe@oracle.com> <1251830335.8502.17.camel@laptop> <20090901184455.GA27294@infradead.org> <20090901202747.GC6996@mit.edu> <1251876776.7547.52.camel@twins> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Cc: Christoph Hellwig , Jens Axboe , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, chris.mason@oracle.com, david@fromorbit.com, akpm@linux-foundation.org, jack@suse.cz To: Theodore Tso Return-path: Received: from bombadil.infradead.org ([18.85.46.34]:38099 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750726AbZIBHf2 (ORCPT ); Wed, 2 Sep 2009 03:35:28 -0400 In-Reply-To: <1251876776.7547.52.camel@twins> Sender: linux-fsdevel-owner@vger.kernel.org List-ID: > On Tue, 2009-09-01 at 16:27 -0400, Theodore Tso wrote: > > So perhaps the best argument for not making this be a tunable is that > > in the long run, we will need to put in a better algorithm for > > controlling how much writeback we want to do before we start > > saturating RAID arrays, and in that new algorithm this tunable may no > > longer make sense. Fine; at that point, we can make it go away. For > > now, though, it seems to be the best way to tweak what is going on, > > since I doubt we'll be able to come up with one magic number that will > > satisfy everyone. Also, what is the incentive to actually improve the situation once we merge this? People will say, turn the knob and don't bother us.