From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Charles Coffing" Subject: Re: [PATCH] Fix auto-ballooning of dom0 for HVM domains Date: Mon, 22 May 2006 09:15:49 -0600 Message-ID: <44718203.D169.003C.0@novell.com> References: <571ACEFD467F7749BC50E0A98C17CDD8094E7C7E@pdsmsx403> <44717C34.D169.003C.0@novell.com> <6085df031157d9ce198b72191501db21@cl.cam.ac.uk> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <6085df031157d9ce198b72191501db21@cl.cam.ac.uk> Content-Disposition: inline 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: Kevin Tian , Yunhong Jiang , xen-devel@lists.xensource.com, xen-ia64-devel@lists.xensource.com List-Id: xen-devel@lists.xenproject.org >>> On Mon, May 22, 2006 at 9:03 AM, in message <6085df031157d9ce198b72191501db21@cl.cam.ac.uk>, Keir Fraser wrote: > On 22 May 2006, at 15:51, Charles Coffing wrote: > >> HVM domains need some extra memory free for the shadow page tables, >> otherwise they may crash the entire machine while they are running, or >> the HVM domain itself may crash (exact behavior depends on whether you >> have Yunhong's patch to change BUGs to domain_crash). >> >> This slack space is calculated into the memory size for HVM domains, >> but what happens if you then start a PV domain afterwards? Only the >> minimally required memory is freed up, then the PV domain takes it all, >> leaving the HVM domain with no slack == crash. > > Where does the slack from the previous HVM guest startup go? Are you > saying that dom0 only frees up PV- guest- size minus existing- slack? Correct. Unless, of course, the HVM domain has eaten up some of the slack in the mean-time, in which case dom0 frees up PV-guest-size minus remaining-slack.