From mboxrd@z Thu Jan 1 00:00:00 1970 From: Matthew Wilcox Subject: Re: [PATCH 1/7] Make DISCARD_BARRIER and DISCARD_NOBARRIER writes instead of reads Date: Thu, 3 Sep 2009 11:56:18 -0600 Message-ID: <20090903175617.GA26346@parisc-linux.org> References: <20090829230332.017137693@bombadil.infradead.org> <20090829231121.144124147@bombadil.infradead.org> <1252000340.4483.529.camel@macbook.infradead.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <1252000340.4483.529.camel@macbook.infradead.org> Sender: linux-scsi-owner@vger.kernel.org To: David Woodhouse Cc: Christoph Hellwig , linux-scsi@vger.kernel.org, linux-ide@vger.kernel.org, linux-kernel@vger.kernel.org, liml@rtr.ca, jens.axboe@oracle.com, Matthew Wilcox List-Id: linux-ide@vger.kernel.org On Thu, Sep 03, 2009 at 06:52:20PM +0100, David Woodhouse wrote: > On Sat, 2009-08-29 at 19:03 -0400, Christoph Hellwig wrote: > > > > The commands are conceptually writes, and in the case of IDE and SCSI > > commands actually are writes. They were only reads because we thought > > that would interact better with the elevators. Now the elevators know > > about discard requests, that advantage no longer exists. > > Can you drop the final sentence of that? It isn't true, and I never said > it. No, but you wouldn't give me a changelog entry, so I had to make something up. > s/. Now.*/, but that isn't necessary, and making them writes makes it > easier for the low-level IDE and SCSI code to cope with the fact that > the command has to be sent with a payload./ Thanks. -- Matthew Wilcox Intel Open Source Technology Centre "Bill, look, we understand that you're interested in selling us this operating system, but compare it to ours. We can't possibly take such a retrograde step."