Re: [Xen-ia64-devel] [PATCH] Use saner dom0 memory and vcpu defaults, don't panic on over-allocation

[Isaku Yamahata <yamahata@xxxxxxxxxxxxx>]

On Tue, Jul 31, 2007 at 10:43:44PM -0600, Alex Williamson wrote:
> > +       /* maximum available memory for dom0 */
> > +       max_dom0_pages = avail_domheap_pages() -
> > +                        min(avail_domheap_pages() /
> > +                        16UL, 512UL << (20 - PAGE_SHIFT)) ;
> 
>    I assume this heuristic came from Akio's patch in the thread you
> referenced; can anyone explain how this was derived and why it's
> necessary?  It looks like a fairly random fudge factor.  Thanks,

I guess it comes from compute_dom0_nr_pages() under arch/x86.
However I don't know why compute_dom0_nr_pages() is so.
Anyway It should be different for ia64. While I'm guessing the most
dominant factor is the p2m table, domain0 building process should
be revised for the correct estimation.

BTW alloc_dom0_size() may be confusing because it doesn't allocate anymore.
How about calc_dom0_size()? 
This isn't essential. very minor issue. Just for my preference.

-- 
yamahata

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