From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stefan Richter Subject: Re: [PATCH] ieee1394: sbp2: lower block queue alignment requirement Date: Thu, 25 Jan 2007 22:35:47 +0100 (CET) Message-ID: References: <1168802387.2780.1.camel@mulgrave.il.steeleye.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1168802387.2780.1.camel@mulgrave.il.steeleye.com> Content-Disposition: INLINE List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: linux1394-devel-bounces@lists.sourceforge.net Errors-To: linux1394-devel-bounces@lists.sourceforge.net To: linux1394-devel@lists.sourceforge.net Cc: James Bottomley , linux-scsi@vger.kernel.org List-Id: linux-scsi@vger.kernel.org On 14 Jan, James Bottomley wrote: > The block layer currently provides sector (512) byte alignment > guarantees. However, there has been talk in SCSI of reducing that to > word (4) since that's what most intelligent PCI controllers can cope > with. If you have any alignment constraints, they should be expressed > in the slave configure. From: Stefan Richter Subject: [PATCH update] ieee1394: sbp2: lower block queue alignment requirement The old setting is copy & waste from usb-storage and doesn't apply to sbp2. There is only 4-byte alignment required for everything, except for S/G table elements which have to be 8-byte aligned according to the SBP-2 spec. (They happen to be ____cacheline_aligned in our implementation. Whether that's good is another question.) We now simply don't tune block queue alignment at all. The default alignment would surely never become anything else than a multiple of 4, else tons of calls to blk_queue_dma_alignment would have to be added everywhere in drivers/... Signed-off-by: Stefan Richter --- Index: linux-2.6.20-rc5/drivers/ieee1394/sbp2.c =================================================================== --- linux-2.6.20-rc5.orig/drivers/ieee1394/sbp2.c +++ linux-2.6.20-rc5/drivers/ieee1394/sbp2.c @@ -51,7 +51,6 @@ * Grep for inline FIXME comments below. */ -#include #include #include #include @@ -2012,7 +2011,6 @@ static int sbp2scsi_slave_configure(stru { struct sbp2_lu *lu = (struct sbp2_lu *)sdev->host->hostdata[0]; - blk_queue_dma_alignment(sdev->request_queue, (512 - 1)); sdev->use_10_for_rw = 1; if (sdev->type == TYPE_ROM) -- Stefan Richter -=====-=-=== ---= ==--= http://arcgraph.de/sr/ ------------------------------------------------------------------------- Take Surveys. Earn Cash. Influence the Future of IT Join SourceForge.net's Techsay panel and you'll get the chance to share your opinions on IT & business topics through brief surveys - and earn cash http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV