Re: [PATCH 0/7] Support for GB pages in KVM

[Avi Kivity]

Joerg Roedel wrote:
> On Sat, Mar 28, 2009 at 06:40:08PM -0300, Marcelo Tosatti wrote:
>   
> > On Fri, Mar 27, 2009 at 03:31:52PM +0100, Joerg Roedel wrote:
> >     
> > > Hi,
> > >
> > > this patchset extends the KVM MMU implementation to support 1GB pages as
> > > supported by AMD family 16 processors. These patches enable support for
> > > 1 GB pages with Nested Paging. Support for these pages in the shadow
> > > paging code was also developed but does not run stable yet. The patch
> > > for shadow-paging support is not included in this series and will be
> > > sent out seperatly.
> > >       
> > Looks generally sane. I'm not sure its even worthwhile to support
> > GBpages with softmmu, because the chance of finding an area without
> > shadowed (write protected) pages is much smaller than with 2MB pages.
> >     
>
> Thanks for your review.
>
> The idea behind GB pages in softmmu code was to provide GB pages to the
> guest even if hardware does not support it. This would work better with
> live migration (Only case where we wouldn't have gbpages then would be
> vmx with ept enabled).
>
>   
> > Have any numbers to share?
> >     
>
> No numbers I fully trust by now. I measured a 32% improvement in
> kernbench using nested pages backed with gb pages. I will do some more
> measurements and share some more solid numbers.
>
>   

Compared to 2M pages?  But we're already close to native here.


--
error compiling committee.c: too many arguments to function

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