From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753238AbaHSQLF (ORCPT ); Tue, 19 Aug 2014 12:11:05 -0400 Received: from exprod7og112.obsmtp.com ([64.18.2.177]:34086 "EHLO exprod7og112.obsmtp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751741AbaHSQLD (ORCPT ); Tue, 19 Aug 2014 12:11:03 -0400 MIME-Version: 1.0 In-Reply-To: <20140819160625.GA29770@lst.de> References: <1405678393-11497-1-git-send-email-hch@lst.de> <1405678393-11497-14-git-send-email-hch@lst.de> <885d029677826efe0cfe3803411cbdba@mail.gmail.com> <20140819160625.GA29770@lst.de> Date: Tue, 19 Aug 2014 21:41:01 +0530 Message-ID: Subject: Re: [PATCH 13/14] scsi: add support for a blk-mq based I/O path. From: Kashyap Desai To: Christoph Hellwig Cc: James Bottomley , linux-scsi@vger.kernel.org, Jens Axboe , Bart Van Assche , Mike Christie , "Martin K. Petersen" , Robert Elliott , Webb Scales , linux-kernel@vger.kernel.org Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Aug 19, 2014 at 9:36 PM, Christoph Hellwig wrote: > On Tue, Aug 19, 2014 at 03:51:42AM +0530, Kashyap Desai wrote: >> I read this comment and find that very few drivers are using this >> cmd_list. I think if we remove this cmd_list, performance will scale as I >> am seeing major contention in this lock. >> Just thought to ping you to see if this is known limitation for now or any >> plan to change this lock in near future ? > > Removing the lock entirely and pushing the list into the two drivers > using it is on my TODO list. Bart actually suggested keeping the code in the > SCSI core and having a flag to enabled. Given that I'm too busy to get my full > version done in time, it might be a good idea if someone picks up Barts > idea. Can you send me a patch to add a enable_cmd_list flag to the host > template and only enable it for aacraid and dpt_i2o? > Sure. I will work on relevant code change and will post patch for review. -- Device Driver Developer @ Avagotech Kashyap D. Desai Note - my new email address kashyap.desai@avagotech.com