Re: [PATCH 1 of 2 RFC] xen, pod: Zero-check recently populated pages (checklast)

[Tim Deegan <tim@xen.org>]

At 13:02 +0100 on 08 Jun (1339160536), Jan Beulich wrote:
> >>> On 08.06.12 at 13:45, George Dunlap <george.dunlap@eu.citrix.com> wrote:
> > --- a/xen/include/asm-x86/p2m.h
> > +++ b/xen/include/asm-x86/p2m.h
> > @@ -287,6 +287,9 @@ struct p2m_domain {
> >          unsigned         reclaim_super; /* Last gpfn of a scan */
> >          unsigned         reclaim_single; /* Last gpfn of a scan */
> >          unsigned         max_guest;    /* gpfn of max guest demand-populate */
> > +#define POD_HISTORY_MAX 128
> > +        unsigned         last_populated[POD_HISTORY_MAX]; /* gpfn of last guest page demand-populated */

This is the gpfns of the last 128 order-9 superpages populated, right?
Also, this line is >80 columns - I think I saw a few others in this series. 

> unsigned long?
> 
> Also, wouldn't it be better to allocate this table dynamically, at
> once allowing its size to scale with the number of vCPU-s in the
> guest?

You could even make it a small per-vcpu array, assuming that the parallel 
scrubbing will be symmetric across vcpus.

Cheers,

Tim.