From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751828Ab0CJFIj (ORCPT ); Wed, 10 Mar 2010 00:08:39 -0500 Received: from rcsinet11.oracle.com ([148.87.113.123]:65397 "EHLO rcsinet11.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750835Ab0CJFIg (ORCPT ); Wed, 10 Mar 2010 00:08:36 -0500 To: Karel Zak Cc: Michael Tokarev , Mike Snitzer , linux-ide@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: ATA 4 KiB sector issues. From: "Martin K. Petersen" Organization: Oracle References: <4B947393.2050002@kernel.org> <170fa0d21003081134g491034e5v4aad4d43853e48ec@mail.gmail.com> <4B95F071.3070400@msgid.tls.msk.ru> <20100309100153.GD18077@nb.net.home> <4B961FE1.5040105@msgid.tls.msk.ru> <20100309121858.GA2020@nb.net.home> Date: Wed, 10 Mar 2010 00:06:25 -0500 In-Reply-To: <20100309121858.GA2020@nb.net.home> (Karel Zak's message of "Tue, 9 Mar 2010 13:18:59 +0100") Message-ID: User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/23.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-Source-IP: acsmt355.oracle.com [141.146.40.155] X-Auth-Type: Internal IP X-CT-RefId: str=0001.0A090208.4B972940.012F:SCFMA4539814,ss=1,fgs=0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org >>>>> "Karel" == Karel Zak writes: [Cleaned up the CC: list from hell] Karel> # cat /sys/block/md8/queue/{minimum,optimal}_io_size Karel> 65536 65536 This one had me puzzled. We set min_io and opt_io correctly in raid5.c depending on number of non-parity disks. And yet it turns into something nonsensical after. Turns out we overrun unsigned int calculating the lowest common multiple in the stacking function. That's why we ended up with the wrong value. I never noticed this because my userland topology regression test tool uses unsigned long. I'll get a patch off to Jens right away. -- Martin K. Petersen Oracle Linux Engineering