From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Daniel P. Berrange" Subject: Re: 3.0.5-rc3: Creating HVM guest fails with: Cannot allocate memory Date: Mon, 30 Apr 2007 20:11:34 +0100 Message-ID: <20070430191134.GO22697@redhat.com> References: <20070426231219.GC17027@redhat.com> <20070427132616.GC13642@redhat.com> <4635E71F.D169.003C.0@novell.com> Reply-To: "Daniel P. Berrange" Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <4635E71F.D169.003C.0@novell.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: Charles Coffing Cc: xen-devel@lists.xensource.com List-Id: xen-devel@lists.xenproject.org On Mon, Apr 30, 2007 at 02:59:08PM -0400, Charles Coffing wrote: > On Fri, Apr 27, 2007 at 7:26 AM, "Daniel P. Berrange" wrote: > > On Fri, Apr 27, 2007 at 07:53:24AM +0100, Keir Fraser wrote: > >> On 27/4/07 00:12, "Daniel P. Berrange" wrote: > >> > >> > The _constructDomain call is failing in xc.domain_create() - the code which > >> > deals with ballooning down Domain-0 is not even run yet - that lives in > >> > the _initDomain method. So HVM domain creation is failing before XenD has > >> > even had a chance to do ballooning. If I manually use 'xm mem-set' to > >> > balloon down Domain-0 ahead of time, everything works just fine. > >> > > >> > I'm at a lose to figure out how to solve this without major re-arranging > >> > of the order of _constructDomain & _initDomain work. Perhaps someone can > >> > figure out an easier fix ? > >> > >> I don't think domain_create() allocates very many pages, although it's > >> possible it's making a default allocation of shadow memory. Assuming not, it > >> may be sufficient to make auto-balloon leave a bit of slack memory rather > >> than try to account for all available memory down to the last page. A few > >> pages might turn out to suffice. Does this problem occur with the very first > >> domain you try to create after booting the machine? > > > > It seems to occurr with any HVM guest I try to create, unless there was > > already > > some free mem (from starting & stopping a previous dom). I'm testing with > > this > > very simple hack which seems to make it work - just ensure the balloon driver > > frees a 10 MB chunk right at the start. Hardcoding is fine because when we > > later get to the _initDomain() method we'll definitely be freeing up much > > more than 10 MB for the HVM guests's actual mem requirements. > > > Keir, > > The problem Daniel fixed for fully virtual affects paravirtual, also. > > We have received bug reports from ISVs of this problem in both the PV > and FV cases. I traced code paths and discovered that FV attempts to > allocate the most memory during the initial domain creation; 64-bit PV > allocates the next most; 32-bit PV allocates the least. So failures > for PV are less common, but not impossible. Indeed - in testing on 64-bit PV over the weekend I saw perhaps 1 in 5 PV creation attempts fail with the not enough memory bug. So it does look like the patch needs to be de-indented to fix PV too. Regards, Dan -- |=- Red Hat, Engineering, Emerging Technologies, Boston. +1 978 392 2496 -=| |=- Perl modules: http://search.cpan.org/~danberr/ -=| |=- Projects: http://freshmeat.net/~danielpb/ -=| |=- GnuPG: 7D3B9505 F3C9 553F A1DA 4AC2 5648 23C1 B3DF F742 7D3B 9505 -=|