From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965206AbbHKO2P (ORCPT ); Tue, 11 Aug 2015 10:28:15 -0400 Received: from bombadil.infradead.org ([198.137.202.9]:53096 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S964946AbbHKO2O (ORCPT ); Tue, 11 Aug 2015 10:28:14 -0400 Date: Tue, 11 Aug 2015 07:28:12 -0700 From: Christoph Hellwig To: Jeff Moyer Cc: Christoph Hellwig , Jens Axboe , linux-kernel@vger.kernel.org, dmilburn@redhat.com Subject: Re: [patch] Revert "block: remove artifical max_hw_sectors cap" Message-ID: <20150811142812.GA17958@infradead.org> References: <20150721130246.GA28676@infradead.org> <20150730135134.GA14734@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.23 (2014-03-12) X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Aug 10, 2015 at 01:23:48PM -0400, Jeff Moyer wrote: > Unfortunately, I'm unable to reproduce your results (though my test > setup uses SAS disks, not SATA). I tried with a 10 data disk md RAID5, > with 32k and 128k chunk sizes. I modified the fio program to read/write > multiples of the stripe width, and I also used aio-stress over a range > of queue depth and I/O sizes for read, write, random read and random > write. I didn't see any measurable performance difference. Do you > still have access to your test setup? Unfortuntately I don't have access to a large RAID setup at the moment. > What do you think about reinstituting the artificial max_sectors_kb cap, > but bumping the default up from 512KB to 1280KB? I had our performance > team run numbers on their test setup (which is a 12 disk raid0 with 32k > chunk size, fwiw) with max_sectors_kb set to 1280 and, aside from one > odd data point, things looked good. Let's settle on that for 4.2 and then look it in more detail. > > Cheers, > Jeff ---end quoted text---