From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752523AbaFMGnJ (ORCPT ); Fri, 13 Jun 2014 02:43:09 -0400 Received: from michel.telenet-ops.be ([195.130.137.88]:50077 "EHLO michel.telenet-ops.be" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752069AbaFMGnH (ORCPT ); Fri, 13 Jun 2014 02:43:07 -0400 Message-ID: <539A9D71.7020504@acm.org> Date: Fri, 13 Jun 2014 08:42:57 +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 , 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: > The usage of blk-mq dramatically decreases CPU usage under all workloads going > down from 100% CPU usage that the old setup can hit easily to usually less > than 20% for maxing out storage subsystems with 512 byte reads and writes, > and it allows to easily achieve millions of IOPS. 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. Thanks Christoph for writing up this excellent summary. In case anyone is wondering which LLD changes Christoph is referring to: the tests I ran myself were with an SRP initiator driver modified to use multiple RDMA channels between initiator and target instead of a single channel. I will post these changes for review on the linux-rdma mailing list as soon as I have the time. Bart.