From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jeremy Fitzhardinge Subject: Re: [PATCH 0 of 3] Remus: control tool Date: Wed, 02 Dec 2009 10:17:50 -0800 Message-ID: <4B16AF4E.3050105@goop.org> References: Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: Keir Fraser Cc: "andy@cs.ubc.ca" , "xen-devel@lists.xensource.com" , "konrad.wilk@oracle.com" List-Id: xen-devel@lists.xenproject.org On 12/02/09 00:07, Keir Fraser wrote: > The issue in 2.6.18 was that, if doing back-to-back save/restores, the next > event-channel notification could come in before domU was finished with > previous s/r cycle, and then the notification got dropped. There are a > number of ways of dealing with that of course: I implemented a little state > machine; or you could probably do it with some kind of ticket-based scheme; > or perhaps have the evtchn irq handler spawn a kthread which blocks on the > mutex (I liked that one least as it needs to allocate resources). > Hm, my first thought is "why does that matter?". But I guess the host/guest save protocol is fairly brittle, and if the guest doesn't respond to a particular save it will get wedged. But then, should the control stack be sending back to back save requests? Shouldn't it wait until the previous save has finished? J