Re: [Xen-devel] Xen balloon driver improvement (version 1)

[Wei Liu <wei.liu2@xxxxxxxxxx>]

On Thu, Oct 23, 2014 at 12:00:40PM +0100, Ian Campbell wrote:
> On Wed, 2014-10-22 at 19:29 +0100, Wei Liu wrote:
> 
> > > > For instance, balloon driver can maintain three queues:
> > > >
> > > > 1. queue for 2 MB pages
> > > > 1. queue for 4 KB pages (delegated to core balloon driver)
> > > > 1. queue for pages used to mapped pages from other domain
> > > 
> > > What about 1GB pages?
> > > 
> > 
> > I wouldn't bother with 1GB pages here.
> 
> Guests which don't have special privileges are limited to 2M contiguous
> allocations anyway, to stop them from consuming "precious" higher order
> mappings.
> 
> I'm not sure that's still worthwhile (e.g. is it valid on ARM or
> shadow/HAP x86? I'm not sure).
> 
> > It would require too much work to coalesce 4KB pages to 1GB pages. 
> 
> FWIW in practice You'd probably coalesce 4K pages into 2M  and then 2M
> into 1G.
> 

That's what I meant. Still, that's a very big number.

Wei.

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