From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262373AbTEZX4U (ORCPT ); Mon, 26 May 2003 19:56:20 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262379AbTEZX4U (ORCPT ); Mon, 26 May 2003 19:56:20 -0400 Received: from neon-gw-l3.transmeta.com ([63.209.4.196]:44303 "EHLO neon-gw.transmeta.com") by vger.kernel.org with ESMTP id S262373AbTEZX4T (ORCPT ); Mon, 26 May 2003 19:56:19 -0400 Date: Mon, 26 May 2003 17:09:03 -0700 (PDT) From: Linus Torvalds To: Nick Piggin cc: Jens Axboe , James Bottomley , Linux Kernel Subject: Re: [BK PATCHES] add ata scsi driver In-Reply-To: <3ED2AA37.4000304@cyberone.com.au> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 27 May 2003, Nick Piggin wrote: > > There is an elevator notifier which is called on request > completion in Andrew's tree (needed for AS io scheduler). This > can be used to do what you want. Well, yeah, sure, you can use it to keep track of outstanding requests. But wouldn't it be nicer to see them in the first place? The question being: how do you sanely avoid adding more requests to the queue if you start seeing starvation? Or if adding more requests, at least using an ordered tag or a barrier or whatever to make sure that you tell the disk that the new request must not be done before the old one has finally been satisfied? I think you'd want to see the old requests in order to be able to make that decision reasonably well. This is clearly not a 2.6.x issue, btw. Linus