Re: [patch 00/13] RFC: out of sync shadow

Marcelo Tosatti
2008-09-12T18:10:06Z

On Fri, Sep 12, 2008 at 09:12:03AM -0600, David S. Ahern wrote:
>
>
> Marcelo Tosatti wrote:
> > On Thu, Sep 11, 2008 at 10:05:12PM -0600, David S. Ahern wrote:
> >
> > David,
> >
> > Please reload the kvm-intel module with "bypass_guest_pf=0" option.
> >
> >
>
> DOH. You mentioned that in your description, and I forgot to disable it.
> Works fine now.
>
> Guest behavior is amazing. After 30 min of uptime, kscand shows only
> 17secs of cpu usage. Before, kscand was hitting over a minute after
> about 10 minutes of uptime.

Great. Note that its not fully optimized for the RHEL3 highpte kscand
case, which calls invlpg for present pagetable entries.

The current patchset simply invalidates the shadow on invlpg, meaning
that the next access will cause a pagefault exit.

It can instead read the guest pte and prefault, saving one exit per
test-and-clear-accessed operation.