Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261970AbTEZR7u (ORCPT ); Mon, 26 May 2003 13:59:50 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261989AbTEZR7u (ORCPT ); Mon, 26 May 2003 13:59:50 -0400 Received: from nat9.steeleye.com ([65.114.3.137]:58116 "EHLO hancock.sc.steeleye.com") by vger.kernel.org with ESMTP id S261970AbTEZR7p (ORCPT ); Mon, 26 May 2003 13:59:45 -0400 Subject: Re: [BK PATCHES] add ata scsi driver From: James Bottomley To: torvalds@transmeta.com, Jens Axboe Cc: Linux Kernel Content-Type: text/plain Content-Transfer-Encoding: 7bit X-Mailer: Ximian Evolution 1.0.8 (1.0.8-9) Date: 26 May 2003 14:12:49 -0400 Message-Id: <1053972773.2298.177.camel@mulgrave> Mime-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1653 Lines: 46 On Mon, May 26 2003, Linus Torvalds wrote: > > What does the block layer need, that it doesn't have now? > > Exactly. I'd _love_ for people to really think about this. In discussion with Jeff, it seems most of what he wants is already there. He just doesn't know it yet :-) Maybe that's my problem as well, maybe the code / comments / doc / whatever is not clear enough. My wishlist for this would be: 1. Unified SG segment allocation. The SCSI layer currently has a mempool implementation to cope with this, is there a reason it can't become block generic? 2. Device locality awareness. Quite a bit of the esoteric SCSI queueing code occurs because we have two type of queue events: a. device can't accept another command---stop queue and restart when the device sends a completion back b. the host adapter is out of resources for *all* its devices. Block all device queues until we free some resources (again, usually a returning command). 3. Perhaps some type of unified command handling. At the moment, we all seem to allocate DMA'able regions for our commands/taskfiles/whatever and attach them to reqest->special. Then we need to release them again before completing the request. 4. Same thing goes for sense buffers. 5. There needs to be some amalgam of the SCSI code for dynamic tag command queue depth handling. OK, I'll stop now. James - 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/