From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753470AbbG3OIV (ORCPT ); Thu, 30 Jul 2015 10:08:21 -0400 Received: from mx1.redhat.com ([209.132.183.28]:41232 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751255AbbG3OIU (ORCPT ); Thu, 30 Jul 2015 10:08:20 -0400 From: Jeff Moyer To: Christoph Hellwig Cc: Jens Axboe , linux-kernel@vger.kernel.org, dmilburn@redhat.com Subject: Re: [patch] Revert "block: remove artifical max_hw_sectors cap" References: <20150721130246.GA28676@infradead.org> <20150730135134.GA14734@infradead.org> X-PGP-KeyID: 1F78E1B4 X-PGP-CertKey: F6FE 280D 8293 F72C 65FD 5A58 1FF8 A7CA 1F78 E1B4 X-PCLoadLetter: What the f**k does that mean? Date: Thu, 30 Jul 2015 10:08:18 -0400 In-Reply-To: <20150730135134.GA14734@infradead.org> (Christoph Hellwig's message of "Thu, 30 Jul 2015 06:51:34 -0700") Message-ID: User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.3 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Christoph Hellwig writes: > Hi Jeff, > > thanks for the detailed numbers! > > The bigger I/O size makes a drastic impact for Linux software RAID > setups, for which this was a driver. For the RAID5/6 over SATA disks > setups that I was benchmarking this it gives between 20 and 40% better > sequential read and write numbers. OK, thanks for the details on the setup. Did you try with max_sector_kb values between 512 and 32767? I wonder if we can find a happy middle ground, like 1280 or even 2048. I'll try to setup a software raid 5 with 10 disks and get back to you. If you have a preference for the exact geometry, please speak up. Thanks! Jeff