From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jason Gunthorpe Subject: Re: [PATCH RFC] nvme-rdma: support devices with queue size < 32 Date: Wed, 29 Mar 2017 10:27:51 -0600 Message-ID: <20170329162751.GA7113@obsidianresearch.com> References: <1315914765.312051621.1490259849534.JavaMail.zimbra@kalray.eu> <20170323140042.GA30536@lst.de> <277345557.313693033.1490279818647.JavaMail.zimbra@kalray.eu> <4951fac6-662f-29a6-5ba5-38d37a2c2dca@grimberg.me> <1180136633.325075447.1490700022740.JavaMail.zimbra@kalray.eu> <8dc0414f-be90-ee30-0f66-8cee26c4c2aa@grimberg.me> <20170329132918.GA32072@obsidianresearch.com> <406682b9-d7ca-4718-5830-7940d2822bc0@grimberg.me> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <406682b9-d7ca-4718-5830-7940d2822bc0-NQWnxTmZq1alnMjI0IkVqw@public.gmane.org> Sender: linux-rdma-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Sagi Grimberg Cc: Marta Rybczynska , Christoph Hellwig , linux-nvme-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, keith busch , axboe-b10kYP2dOMg@public.gmane.org, Samuel Jones , Max Gurtovoy , Leon Romanovsky List-Id: linux-rdma@vger.kernel.org On Wed, Mar 29, 2017 at 06:47:54PM +0300, Sagi Grimberg wrote: > For each I/O we post up to 2 work requests, 1 for memory registration > and 1 for sending an I/O request (and 1 for local invalidation if the > target doesn't do it for us, but that is not the case here). So if our > queue depth is X, we size our completion queue to be X*3, and we need > to make sure we signal every (X*3)/2. ??? If your SQ is X and your CQ is X*3 you need to signal at X/2. Jason -- To unsubscribe from this list: send the line "unsubscribe linux-rdma" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html