From: Eric Sandeen Subject: Re: I/O topology fixes for big physical block size Date: Thu, 30 Sep 2010 12:07:02 -0500 Message-ID: <4CA4C3B6.9000104@redhat.com> References: <4CA118FF.1080100@fusionio.com> <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> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit To: "Ted Ts'o" , "Martin K. Petersen" , Mike Snitzer , Jens Axboe , "James.Bottomley@hansenpartnership Return-path: Received: from mx1.redhat.com ([209.132.183.28]:50873 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755809Ab0I3RHJ (ORCPT ); Thu, 30 Sep 2010 13:07:09 -0400 In-Reply-To: <20100930163047.GA4098@thunk.org> Sender: linux-ext4-owner@vger.kernel.org List-ID: 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? > say, 16k or 32k, maybe we should use to calculate for > s_raid_stripe_width? Perhaps, though really ext4 still doesn't do -that- much with the value, anyway... -Eric