From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jens Axboe Subject: Re: [PATCH RFC 0/4] use scatter lists for all block pc requests and simplify hw handlers Date: Tue, 7 Jun 2005 20:07:20 +0200 Message-ID: <20050607180719.GB8172@suse.de> References: <1117847972.23638.62.camel@mina> <1117901234.5005.9.camel@mulgrave> <1117955727.4961.8.camel@mina> <1117982408.4990.12.camel@mulgrave> <1117998665.4990.17.camel@mulgrave> <42A3E275.6030106@torque.net> <1118067544.5045.17.camel@mulgrave> <42A59C35.5060207@torque.net> <1118159966.4813.8.camel@mulgrave> Reply-To: device-mapper development Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <1118159966.4813.8.camel@mulgrave> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: dm-devel-bounces@redhat.com Errors-To: dm-devel-bounces@redhat.com To: James Bottomley Cc: LIRANS@il.ibm.com, Mike Christie , Douglas Gilbert , device-mapper development , linux-scsi List-Id: linux-scsi@vger.kernel.org On Tue, Jun 07 2005, James Bottomley wrote: > On Tue, 2005-06-07 at 23:08 +1000, Douglas Gilbert wrote: > > I don't think it is important and I'm not aware of any > > real world applications that are using it. Naturally, > > I will find out if that is actually true after it > > gets removed. > > Heh, true. OK, let's do this: I'll remove it from the sg driver and > make sg use the do_command (or it's successor) interface. If an actual > user for the iovecs does turn up, I'll add it to the block layer (it's a > fairly well understood multi-bio request setup) and make sg and also the > block layer SG_IO use it. Why multi-bio? No one should ever have to build a request with multiple bio's in one go, that's pointless. The only reason multi-bio requests exist is because of the file systems not submitting big extents in one submission. The whole io path would be faster and simpler were it not for multi-bio requests :-) A single bio can contain just as much data. -- Jens Axboe