From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christoph Hellwig Subject: Re: [PATCH] hpsa: scsi-mq support Date: Sun, 13 Nov 2016 12:58:41 +0100 Message-ID: <20161113115841.GA4818@lst.de> References: <1478879194-32529-1-git-send-email-hare@suse.de> <20161111163532.GA14922@infradead.org> <39d1198d-eb49-71ed-9139-f0efd9eefd0d@suse.com> <20161112173223.GA22158@infradead.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from verein.lst.de ([213.95.11.211]:37872 "EHLO newverein.lst.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933584AbcKML6n (ORCPT ); Sun, 13 Nov 2016 06:58:43 -0500 Content-Disposition: inline In-Reply-To: Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: Hannes Reinecke Cc: Christoph Hellwig , Hannes Reinecke , Christoph Hellwig , "Martin K. Petersen" , James Bottomley , Don Brace , linux-scsi@vger.kernel.org, Jens Axboe On Sun, Nov 13, 2016 at 10:44:47AM +0100, Hannes Reinecke wrote: > One day to mark with bright red in the calendar. > > Christoph Hellwig is telling me _NOT_ to use scsi-mq. That's not what I'm doing. > This patch was done so see what would needed to be done to convert a legacy > driver. > As I was under the impression that scsi-mq is the way forward, seeing that > it should be enabled per default. > But I must have been mistaken. Apparently. What I am doing is to tell you you should not expose multiple queues unless the hardware actually has multiple submissions queues. The blk-mq and scsi-mq code works just fine with a single submission queue, and the hpsa driver in particular works really well with scsi-mq and a single submission queue. E.g. the RAID HBA on slide 19 of this presentations is an hpsa one: http://events.linuxfoundation.org/sites/events/files/slides/scsi.pdf