Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S269276AbTGJNn1 (ORCPT ); Thu, 10 Jul 2003 09:43:27 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S269278AbTGJNn1 (ORCPT ); Thu, 10 Jul 2003 09:43:27 -0400 Received: from ns.virtualhost.dk ([195.184.98.160]:20953 "EHLO virtualhost.dk") by vger.kernel.org with ESMTP id S269276AbTGJNn0 (ORCPT ); Thu, 10 Jul 2003 09:43:26 -0400 Date: Thu, 10 Jul 2003 15:57:47 +0200 From: Jens Axboe To: Marcelo Tosatti Cc: lkml , "Stephen C. Tweedie" , Alan Cox , Jeff Garzik , Andrew Morton , Andrea Arcangeli , Chris Mason , Alexander Viro Subject: Re: RFC on io-stalls patch Message-ID: <20030710135747.GT825@suse.de> References: Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1395 Lines: 36 On Tue, Jul 08 2003, Marcelo Tosatti wrote: > > Hello people, > > To get better IO interactivity and to fix potential SMP IO hangs (due to > missed wakeups) we, (Chris Mason integrated Andrea's work) added > "io-stalls-10" patch in 2.4.22-pre3. > > The "low-latency" patch (which is part of io-stalls-10) seemed to be a > good approach to increase IO fairness. Some people (Alan, AFAIK) are a bit > concerned about that, though. > > Could you guys, Stephen, Andrew and maybe Viro (if interested :)) which > havent been part of the discussions around the IO stalls issue take a look > at the patch, please? > > It seems safe and a good approach to me, but might not be. Or have small > "glitches". Well, I have one naive question. What prevents writes from eating the entire request pool now? In the 2.2 and earlier days, we reserved the last 3rd of the requests to writes. 2.4.1 and later used a split request list to make that same guarentee. I only did a quick read of the patch so maybe I'm missing the new mechanism for this. Are we simply relying on fair (FIFO) request allocation and oversized queue to do its job alone? -- Jens Axboe - 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/