RE: [Xen-devel] Re: PoD issue

[Ian Pratt <Ian.Pratt@xxxxxxxxxxxxx>]

> On Thu, Feb 4, 2010 at 2:12 PM, George Dunlap
> <George.Dunlap@xxxxxxxxxxxxx> wrote:
> > Yeah, the OSS tree doesn't get the kind of regression testing it
> > really needs at the moment.  I was using the OSS balloon drivers when
> > I implemented and submitted the PoD code last year.  I didn't have any
> > trouble then, and I was definitely using up all of the memory.  But I
> > haven't done any testing on OSS since then, basically.
> >
> 
> Is it expected that booting HVM guests with maxmem > memory is
> unstable? In testing 3.4.3-rc2 (kernel 2.6.18 c/s 993) I can easily
> crash the guest and occasionally the entire server.

Obviously the platform should never crash, and that's very concerning.

Are you running a balloon driver in the guest? It's essential that you do, 
because it needs to get in fairly early in the guest boot and allocate the 
difference between maxmem and target memory. The populate-on-demand code exists 
just to cope with things like the memory scrubber running ahead of the balloon 
driver. If you're not running a balloon driver the guest is doomed to crash as 
soon as it tries using more than target memory.

All of this requires coordination between the tool stack, PoD code, and PV 
drivers so that sufficient memory gets ballooned out. I expect the combination 
that has had most testing is the XCP toolstack and Citrix PV windows drivers.

Ian


 



You need to be running a balloon driver in the guest: it needs 

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