From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933152AbaFQO2H (ORCPT ); Tue, 17 Jun 2014 10:28:07 -0400 Received: from albert.telenet-ops.be ([195.130.137.90]:46907 "EHLO albert.telenet-ops.be" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932985AbaFQO2F (ORCPT ); Tue, 17 Jun 2014 10:28:05 -0400 Message-ID: <53A05068.4080702@acm.org> Date: Tue, 17 Jun 2014 16:27:52 +0200 From: Bart Van Assche User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.5.0 MIME-Version: 1.0 To: Christoph Hellwig , James Bottomley CC: Jens Axboe , Bart Van Assche , Robert Elliot , linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: scsi-mq References: <1402580946-11470-1-git-send-email-hch@lst.de> In-Reply-To: <1402580946-11470-1-git-send-email-hch@lst.de> X-Enigmail-Version: 1.6 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 06/12/14 15:48, Christoph Hellwig wrote: > Bart and Robert have helped with some very detailed measurements that they > might be able to send in reply to this, although these usually involve > significantly reworked low level drivers to avoid other bottle necks. In case someone would like to see the results of the measurements I ran, these results can be found here: https://docs.google.com/file/d/0B1YQOreL3_FxUXFMSjhmNDBNNTg. Two important conclusions from the data in that PDF document are as follows: - A small but significant performance improvement for the traditional SCSI mid-layer (use_blk_mq=N). - A very significant performance improvement for multithreaded workloads with use_blk_mq=Y. As an example, the number of I/O operations per second reported for the random write test increased with 170%. That means 2.7 times the performance of use_blk_mq=N. I think this means the scsi-mq patches are ready for wider use. Bart.