From: Mike Snitzer Subject: Re: I/O topology fixes for big physical block size Date: Thu, 30 Sep 2010 13:33:43 -0400 Message-ID: <20100930173342.GB31945@redhat.com> References: <20100927231551.GA15653@redhat.com> <4CA16F6A.1090904@fusionio.com> <4CA17B13.7080801@redhat.com> <20100928141545.GA21587@redhat.com> <20100928205741.GA22257@thunk.org> <4CA25FEA.6040505@redhat.com> <20100930163047.GA4098@thunk.org> <4CA4C3B6.9000104@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: "Ted Ts'o" , "Martin K. Petersen" , Jens Axboe , "James.Bottomley@hansenpartnership.com" , "linux-scsi@vger.kernel.org" , "linux-ext4@vger.kernel.org" To: Eric Sandeen Return-path: Content-Disposition: inline In-Reply-To: <4CA4C3B6.9000104@redhat.com> Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-ext4.vger.kernel.org On Thu, Sep 30 2010 at 1:07pm -0400, Eric Sandeen wrote: > On 09/30/2010 11:30 AM, Ted Ts'o wrote: > > On Tue, Sep 28, 2010 at 04:36:42PM -0500, Eric Sandeen wrote: > >> Ok, then it sounds like mkfs.ext4's refusal to make fs blocksize less > >> than device physical sectorsize without -F is broken, and that should > >> be removed. I'd say issue a warning in the case but if there's a 16k > >> physical device maybe there's no point in warning either? > > > > If the device physical sectorsize is that big, should we perhaps use > > that as a hint to align writes to that blocks aligned with that > > physical sectorsize? Right now we use the optimal I/O size, but if > > the optimal I/O size is not specified and the physical sectorsize is, > > I can't keep track of all the parameters, is it ever true that optimal > I/O size isn't specified? Yes optimal_io_size may be 0. But minimum_io_size will always be scaled up to at least match physical_block_size. In any case: this 1MB physical_block_size device, which started this thread, also has 1MB for both minimum_io_size and optimal_io_size. Mike