From mboxrd@z Thu Jan 1 00:00:00 1970 From: Russell King Subject: Re: [PATCHSET] block: fix PIO cache coherency bug, take 2 Date: Mon, 5 Jun 2006 16:48:38 +0100 Message-ID: <20060605154837.GD26666@flint.arm.linux.org.uk> References: <1149392479501-git-send-email-htejun@gmail.com> <20060604204444.GF4484@flint.arm.linux.org.uk> <20060604222347.GG4484@flint.arm.linux.org.uk> <1149517656.3489.15.camel@mulgrave.il.steeleye.com> <20060605144456.GA26666@flint.arm.linux.org.uk> <1149521085.3489.24.camel@mulgrave.il.steeleye.com> <20060605153420.GB26666@flint.arm.linux.org.uk> <1149522460.3489.26.camel@mulgrave.il.steeleye.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <1149522460.3489.26.camel@mulgrave.il.steeleye.com> Sender: linux-scsi-owner@vger.kernel.org To: James Bottomley Cc: Tejun Heo , Jens Axboe , Dave Miller , bzolnier@gmail.com, jgarzik@pobox.com, mattjreimer@gmail.com, Guennadi Liakhovetski , lkml , linux-ide@vger.kernel.org, linux-scsi@vger.kernel.org List-Id: linux-ide@vger.kernel.org On Mon, Jun 05, 2006 at 10:47:40AM -0500, James Bottomley wrote: > On Mon, 2006-06-05 at 16:34 +0100, Russell King wrote: > > What has zero copy (your reply) got to do with faulting pages into > > userspace (my message). I'm sorry, I don't understand why you've > > brought this up. > > The zero copy case is the case where we end up with user and kernel > mappings simultaneously on the page. The nopage (or fault) case is > where we end up with them sequentially. Both cases actually require the > same cache treatment, but it's easiest to understand in the zero copy > case. When does the zero copy case occur? -- Russell King Linux kernel 2.6 ARM Linux - http://www.arm.linux.org.uk/ maintainer of: 2.6 Serial core