From mboxrd@z Thu Jan 1 00:00:00 1970 From: Russell King Subject: Re: [PATCH] ide: add dcache flushing after PIO Date: Sat, 7 Jan 2006 21:22:49 +0000 Message-ID: <20060107212248.GJ31384@flint.arm.linux.org.uk> References: <43A7FE89.4040909@gmail.com> <58cb370e0512200823g50de6e14n148e27e4a4c267f7@mail.gmail.com> <20051221094847.GA12279@htj.dyndns.org> <20051221140022.GA25001@htj.dyndns.org> <20051221140344.GA1736@flint.arm.linux.org.uk> <43A969FD.3090106@gmail.com> <58cb370e0512210757n25ddd614p33f3d70c8ff813cd@mail.gmail.com> <20051221175416.GH1736@flint.arm.linux.org.uk> <20060107170623.GA15171@flint.arm.linux.org.uk> <58cb370e0601071217x390fc1fpbbc9866b38ac28d7@mail.gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from caramon.arm.linux.org.uk ([212.18.232.186]:59151 "EHLO caramon.arm.linux.org.uk") by vger.kernel.org with ESMTP id S1030583AbWAGVW5 (ORCPT ); Sat, 7 Jan 2006 16:22:57 -0500 Content-Disposition: inline In-Reply-To: <58cb370e0601071217x390fc1fpbbc9866b38ac28d7@mail.gmail.com> Sender: linux-ide-owner@vger.kernel.org List-Id: linux-ide@vger.kernel.org To: Bartlomiej Zolnierkiewicz Cc: Tejun Heo , James Steward , "linux-ide@vger.kernel.org" On Sat, Jan 07, 2006 at 09:17:11PM +0100, Bartlomiej Zolnierkiewicz wrote: > On 1/7/06, Russell King wrote: > > On Wed, Dec 21, 2005 at 05:54:16PM +0000, Russell King wrote: > > > DaveM vetoed that with good reason - the VM layer doesn't know whether > > > the driver is doing PIO or not. If it is doing PIO, it needs the > > > cache flush. If it's doing DMA, the cache flush is entirely a > > > performance bottleneck. > > > > Bart, > > > > Did you miss my message, or have you decided to pay no further > > attention to this issue? > > No, I'm waiting for ARM folks to give Tejun and me some feedback. We have, and I think it's been soo long that you're now confused. See the entire thread on marc: http://marc.theaimsgroup.com/?t=113517374400003&r=1&w=2 Yes, Tejun produced a patch and I queried whether it was going to far. There was a bit of discussion which resulted in a comment from you saying: | After reading excellent explanation by rmk I think that it should be | fixed at VM layer (filemap_nopage() perhaps). To which I replied: | DaveM vetoed that with good reason - the VM layer doesn't know whether | the driver is doing PIO or not. If it is doing PIO, it needs the | cache flush. If it's doing DMA, the cache flush is entirely a | performance bottleneck. That's where we stand now - I'm waiting for some progress. > So far there was none and nobody seemed to care to test/comment > this patch ("works fine" is enough). Odd, as demonstrated by the linux-ide archives above I've already commented on it. > What about testing the patch instead? Since there hasn't been a follow-up patch, there isn't anything to test. Please can we have a revised patch so folk _can_ do some testing? -- Russell King Linux kernel 2.6 ARM Linux - http://www.arm.linux.org.uk/ maintainer of: 2.6 Serial core