Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751301AbWCAWbK (ORCPT ); Wed, 1 Mar 2006 17:31:10 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751914AbWCAWbJ (ORCPT ); Wed, 1 Mar 2006 17:31:09 -0500 Received: from stat9.steeleye.com ([209.192.50.41]:55189 "EHLO hancock.sc.steeleye.com") by vger.kernel.org with ESMTP id S1751329AbWCAWbI (ORCPT ); Wed, 1 Mar 2006 17:31:08 -0500 Subject: Re: sg regression in 2.6.16-rc5 From: James Bottomley To: Mike Christie Cc: dougg@torque.net, Linus Torvalds , Matthias Andree , Mark Rustad , linux-scsi@vger.kernel.org, Linux Kernel Mailing List In-Reply-To: <1141245769.9586.6.camel@max> References: <4404AA2A.5010703@torque.net> <20060301083824.GA9871@merlin.emma.line.org> <4405F6F1.9040106@torque.net> <1141245769.9586.6.camel@max> Content-Type: text/plain Date: Wed, 01 Mar 2006 16:30:35 -0600 Message-Id: <1141252235.3276.63.camel@mulgrave.il.steeleye.com> Mime-Version: 1.0 X-Mailer: Evolution 2.2.3 (2.2.3-2.fc4) Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1193 Lines: 28 On Wed, 2006-03-01 at 14:42 -0600, Mike Christie wrote: > The current sg driver should use alloc_pages() with an order that should > get 32 KB. If the order being passed to alloc_pages() in sg.c is only > getting one page by default that is bug. > The generic routines now being used can turn that 32KB segment into > multiple 4KB ones if the LLD does not support clustering. To be honest, the original behaviour was a bug. A device that doesn't enable clustering is telling us it can't take anything other than PAGE_SIZE chunks ... trying to give it more is likely to end in tears. However ... I'm not sure we actually have any devices that anyone can identify which truly can't enable clustering (a lot which have it disabled, I suspect, are that way historically because their writers didn't trust the clustering algorithm). So ... I think we can go ahead and cautiously enable clustering (as a separate patch like Jens suggested). 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/