From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christoph Hellwig Subject: Re: scsi-mq V2 Date: Thu, 10 Jul 2014 06:50:51 -0700 Message-ID: <20140710135051.GA28227@infradead.org> References: <1403715121-1201-1-git-send-email-hch@lst.de> <20140708144829.GA5539@infradead.org> <53BD7041.5010300@interlog.com> <53BD9A24.7010203@kernel.dk> <94D0CD8314A33A4D9D801C0FE68B402958B9628B@G9W0745.americas.hpqcorp.net> <20140710062040.GB20146@infradead.org> <20140710133609.GO12478@kvack.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20140710133609.GO12478@kvack.org> Sender: linux-kernel-owner@vger.kernel.org To: Benjamin LaHaise Cc: "Elliott, Robert (Server Storage)" , Jens Axboe , "dgilbert@interlog.com" , James Bottomley , Bart Van Assche , "linux-scsi@vger.kernel.org" , "linux-kernel@vger.kernel.org" List-Id: linux-scsi@vger.kernel.org On Thu, Jul 10, 2014 at 09:36:09AM -0400, Benjamin LaHaise wrote: > There is one possible concern that could be exacerbated by other changes in > the system: if the application is running close to the bare minimum number > of requests allocated in io_setup(), the per cpu reference counters will > have a hard time batching things. It might be worth testing with an > increased number of requests being allocated if this is the case. Well, Robert said reverting the two aio commits didn't help. Either he didn't manage to boot into the right kernel, or we need to look elsewhere for the culprit.