From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S270531AbTGNFex (ORCPT ); Mon, 14 Jul 2003 01:34:53 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S270532AbTGNFew (ORCPT ); Mon, 14 Jul 2003 01:34:52 -0400 Received: from ns.virtualhost.dk ([195.184.98.160]:13224 "EHLO virtualhost.dk") by vger.kernel.org with ESMTP id S270531AbTGNFen (ORCPT ); Mon, 14 Jul 2003 01:34:43 -0400 Date: Mon, 14 Jul 2003 07:49:18 +0200 From: Jens Axboe To: Andrea Arcangeli Cc: Chris Mason , Marcelo Tosatti , lkml , "Stephen C. Tweedie" , Alan Cox , Jeff Garzik , Andrew Morton , Alexander Viro Subject: Re: RFC on io-stalls patch Message-ID: <20030714054918.GD843@suse.de> References: <20030710135747.GT825@suse.de> <1057932804.13313.58.camel@tiny.suse.com> <20030712073710.GK843@suse.de> <1058034751.13318.95.camel@tiny.suse.com> <20030713090116.GU843@suse.de> <20030713191921.GI16313@dualathlon.random> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20030713191921.GI16313@dualathlon.random> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Sun, Jul 13 2003, Andrea Arcangeli wrote: > On Sun, Jul 13, 2003 at 11:01:16AM +0200, Jens Axboe wrote: > > No I don't have anything specific, it just seems like a bad heuristic to > > get rid of. I can try and do some testing tomorrow. I do feel strongly > > well, it's not an heuristic, it's a simplification and it will certainly > won't provide any benefit (besides saving some hundred kbytes of ram per > harddisk that is a minor benefit). You are missing my point - I don't care about loosing the extra request list, I never said anything about that in this thread. I care about loosing the reserved requests for reads. And we can do that just fine with just holding back a handful of requests. > > that we should at least make sure to reserve a few requests for reads > > exclusively, even if you don't agree with the oversized check. Anything > > else really contradicts all the io testing we have done the past years > > that shows how important it is to get a read in ASAP. And doing that in > > Important for latency or throughput? Do you know which is the benchmarks > that returned better results with the two queues, what's the theory > behind this? Forget the two queues, noone has said anything about that. The reserved reads are important for latency reasons, not throughput. -- Jens Axboe