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

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

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.



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