From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Wed, 15 May 2002 07:46:36 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Wed, 15 May 2002 07:46:35 -0400 Received: from gateway.ukaea.org.uk ([194.128.63.73]:62027 "EHLO fuspcnjc.culham.ukaea.org.uk") by vger.kernel.org with ESMTP id ; Wed, 15 May 2002 07:46:34 -0400 Message-ID: <3CE24A34.CEA0CAE0@ukaea.org.uk> Date: Wed, 15 May 2002 12:44:52 +0100 From: Neil Conway X-Mailer: Mozilla 4.78 [en] (X11; U; Linux 2.4.9-31 i686) X-Accept-Language: en MIME-Version: 1.0 To: Martin Dalecki CC: Anton Altaparmakov , Alan Cox , Russell King , linux-kernel@vger.kernel.org Subject: Re: [PATCH] 2.5.15 IDE 61 In-Reply-To: <5.1.0.14.2.20020514202811.01fcc1d0@pop.cus.cam.ac.uk> <3CE22B2B.5080506@evision-ventures.com> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Martin Dalecki wrote: > The only problem is that having a shared lock between two queues apparently > doesn't imply that the queues are behaving atomic on the request level > among each others. Correct - both queues can be active with I/O in flight at the same time. But think about it: if this weren't the case, then the older kernels (using global io_request_lock) would have had to serialize ALL I/O, one request-queue active at a time, for every single block-device... > Apparenty the "sublimation" of the hwgroup and overall cleanup of > data structures, just made many people awake and be aware of problems which > where there already for a very very long time... I'm not quite sure which problems you mean. The busy flag prevents any clash. (But sure, if you change to per-device queues AND you ditch the busy flag you're screwed.) Where is the problem? cheers Neil