From mboxrd@z Thu Jan 1 00:00:00 1970 From: Keir Fraser Subject: Re: Swiotlb Date: Thu, 05 Apr 2007 16:10:45 +0100 Message-ID: References: <1175783021.4124.76.camel@moonstone.uk.level5networks.com> Mime-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1175783021.4124.76.camel@moonstone.uk.level5networks.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: Kieran Mansley , xen-devel@lists.xensource.com List-Id: xen-devel@lists.xenproject.org On 5/4/07 15:23, "Kieran Mansley" wrote: > While writing a driver for a device doing lots of DMA I've hit an > "swiotlb_full()" problem. This surprised me somewhat as I wouldn't have > expected to need the use of the software TLB - it's a 64 bit capable > device on a server with only 2 GB of RAM, and so I'd have expected to be > using a hardware TLB. Is this a peculiarity of Xen, or should I be > right to be surprised? > > I expect I can increase the size of the swiotlb to avoid this problem, > but thought I'd check that there isn't something more fundamentally > wrong first. Well, I would agree that it sounds odd. You should definitely investigate -- you don't want to be invoking the swiotlb on the data path for a modern high-speed device. -- Keir