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Re: [Xen-devel] pre-reservation of memory for domain creation

To: Jan Beulich <JBeulich@xxxxxxxxxx>
Subject: Re: [Xen-devel] pre-reservation of memory for domain creation
From: Tim Deegan <Tim.Deegan@xxxxxxxxxx>
Date: Tue, 9 Feb 2010 10:39:58 +0000
Cc: Dongxiao Xu <dongxiao.xu@xxxxxxxxx>, "xen-devel@xxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxx>, Keir Fraser <Keir.Fraser@xxxxxxxxxxxxx>
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At 16:25 +0000 on 08 Feb (1265646333), Jan Beulich wrote:
> >Hmmm.  Some shadow memory has to be allocated before the VCPUs are
> >initialized so that they can be given monitor pagetables etc.  Some
> >shadow memory has to be allocated before the guest's main memory is
> >assigned because the p2m is built out of shadow memory.
> 
> So is there a way to quantify that? In particular, is that *initial*
> amount in any way dependent on the number of vCPU-s?

Sort of, and not very.  We currently allocate about a page per megabyte
for p2m; we use a small amount per vcpu (maybe as many as 7 pages)
before the vpcu can be scheduled.

> I'm re-raising this question because we're not seeming to make any
> progress towards a satisfactory resolution of the regression c/s 20389
> introduced.

I thought the regression was the Xen crash and that should be fixed by 
the patch I sent.

Tim.

-- 
Tim Deegan <Tim.Deegan@xxxxxxxxxx>
Principal Software Engineer, XenServer Engineering
Citrix Systems UK Ltd.  (Company #02937203, SL9 0BG)

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