Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S263909AbUATDZK (ORCPT ); Mon, 19 Jan 2004 22:25:10 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S263930AbUATDZK (ORCPT ); Mon, 19 Jan 2004 22:25:10 -0500 Received: from mx1.redhat.com ([66.187.233.31]:35987 "EHLO mx1.redhat.com") by vger.kernel.org with ESMTP id S263909AbUATDZE (ORCPT ); Mon, 19 Jan 2004 22:25:04 -0500 Subject: Re: [2.4] scsi per-host lock was Re: smp dead lock of io_request_lock/queue_lock patch From: Doug Ledford To: Marcelo Tosatti Cc: Jens Axboe , hch@lst.de, James Bottomley , linux-kernel@vger.kernel.org, akpm@osdl.org In-Reply-To: References: <20040112151230.GB5844@devserv.devel.redhat.com> <20040112194829.A7078@infradead.org> <1073937102.3114.300.camel@compaq.xsintricity.com> <1074345000.13198.25.camel@compaq.xsintricity.com> Content-Type: text/plain Message-Id: <1074568862.13198.73.camel@compaq.xsintricity.com> Mime-Version: 1.0 X-Mailer: Ximian Evolution 1.4.5 (1.4.5-1) Date: Mon, 19 Jan 2004 22:21:02 -0500 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2585 Lines: 54 On Mon, 2004-01-19 at 21:19, Marcelo Tosatti wrote: > Doug, > > Where can I find a copy of uptodate iorl and mlqueue patchsets ? Red Hat's 2.4.21-9.EL kernel? ;-) Seriously, I've already set up 3 new bk trees on linux-scsi.bkbits.net. They are 2.4-for-marcelo, 2.4-drivers, and 2.4-everything. Right now the trees are still just clones of your current tree. The plan, however, is to sort through all of the scsi patches we put into our kernels and put them into the various trees. Obviously, the everything tree will have both the iorl and mlqueue patches plus the other stuff. The for-marcelo tree is stuff that is agreed to be appropriate for mainline. The drivers tree is where I'll start sticking driver updates that come across linux-scsi for the 2.4 kernel. > I cant enjoy the feeling of splitting a global lock at this point in 2.4's > lifetime, but it has been in RedHat's and SuSE's trees for long. > > A reason to have it its the dependacy of mlqueue patch. You said most > drivers are handling the BUSY/QUEUE_FULL hangs by themselves, you mention > "IBM zfcp" / Emulex which dont. What other drivers suffer from the same > problem ? Well, that's a hard to answer question. First, the problem only shows up on drivers that actually enabled tagged queuing and use a reasonably deep queue depth (normally). So, that automatically strikes out most of the older ISA and crap hardware drivers since they only do a command at a time. The better drivers; aic7xxx (new and old), ncr53c8xx, sym1 and sym2, qla2x00, etc.; work around the problem. It's mainly newer drivers that vendors are starting to write and who don't know the history of the broken mid layer handling of QUEUE_FULL and BUSY situations. So, I cited the two I know of off the top of my head, and there may be others but I would actually have to look at the source code to identify them (when 98% of the scsi market is QLogic and NCR/SYM and aic7xxx, those other drivers fall through the cracks). Of course, one of the other issues is that each driver that tries to handle this situation itself does it in a different manner, and the correctness of those varying implementations is also an issue to consider. -- Doug Ledford 919-754-3700 x44233 Red Hat, Inc. 1801 Varsity Dr. Raleigh, NC 27606 - 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/