From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eli Cohen Subject: Re: Maximum size for memory registration (ibv_reg_mr) Date: Thu, 7 Oct 2010 12:13:16 +0200 Message-ID: <20101007101316.GA9605@mtldesk30> References: <036401cb5c35$85829220$9087b660$@edu> <037101cb5c39$b98036f0$2c80a4d0$@edu> <4CAD9572.5060507@Voltaire.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <4CAD9572.5060507-hKgKHo2Ms0FWk0Htik3J/w@public.gmane.org> Sender: linux-rdma-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Or Gerlitz Cc: Jack Morgenstein , Roland Dreier , Bharath Ramesh , linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: linux-rdma@vger.kernel.org On Thu, Oct 07, 2010 at 11:40:02AM +0200, Or Gerlitz wrote: > Roland Dreier wrote: > >> max_mr_size returned by calling ibv_devinfo is 0xffffffffffffffff. Does this mean the size is unlimited? > > It means that the query function might be returning bad data. What adapter is it? > > Yep, mlx4_ib_query_device does props->max_mr_size = ~0ull ... > > Jack, what would it take to fix that? I took a look and other settings are taken from > dev->dev->caps.xxx where caps is of type mlx4_caps which is in turn filled @ drivers/net/mlx4/main.c > :: mlx4_dev_cap I wasn't sure what field/computation would exactly account for later setting max_mr_size > It is not that trivial to calculate this value. If you create a MR in kernel, it covers the entire address space and the HCA does not pose any limit since you do not consume MTTs. And if you use MTTs then the page size is a parameter in this calculation - huge page, regular page etc. Do leaving it as is seems to be the most accurate thing... -- 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