From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christopher Clark Subject: Re: mapped memory delay? Date: Fri, 18 Feb 2005 22:14:04 +0000 Message-ID: References: Reply-To: cwc22@cam.ac.uk Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit In-Reply-To: Sender: xen-devel-admin@lists.sourceforge.net Errors-To: xen-devel-admin@lists.sourceforge.net List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , List-Archive: To: Xin Zhao Cc: xen-devel@lists.sourceforge.net List-Id: xen-devel@lists.xenproject.org Are you running this on a single processor core? If not, it sounds to me like a cache coherency issue - you'll need a write memory barrier after writing to the req_prod. If you're using the ring macros from io/ring.h this should be already taken care of for you in the push macros. c. On Fri, 18 Feb 2005 16:44:30 -0500 (EST), Xin Zhao wrote: > I ran into the following problem: > > I setup a shared ring page and an event channel between two domains (dom0 > and one domU), DomU increases req_prod by one and notify the dom0 via the > event channel, dom0 then check req_prod pointer and process the request in > the shared ring. But I noticed that sometimes dom0 get the irq triggered > by the notification event, but the req_prod remains the same. This > situation only happened occasionally. Why? Because the req_prod is saved > in the shared, mapped page, I suspect that there is a delay of updates > between two domains. Is that true? If so, how to handle this problem? > > Your advice is highly appreciated! > > -x > > ------------------------------------------------------- > SF email is sponsored by - The IT Product Guide > Read honest & candid reviews on hundreds of IT Products from real users. > Discover which products truly live up to the hype. Start reading now. > http://ads.osdn.com/?ad_id=6595&alloc_id=14396&op=click > _______________________________________________ > Xen-devel mailing list > Xen-devel@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/xen-devel > ------------------------------------------------------- SF email is sponsored by - The IT Product Guide Read honest & candid reviews on hundreds of IT Products from real users. Discover which products truly live up to the hype. Start reading now. http://ads.osdn.com/?ad_id=6595&alloc_id=14396&op=click