RE: [Xen-devel] what happens when a PoD page is touched?

["James Harper" <james.harper@xxxxxxxxxxxxxxxx>]

> 
> > -----Original Message-----
> >
> > I've not seen any slowdown on boot with any version of Windows until
> > I go to actually do the balloon down...
> >
> 
> In that case I guess your slowdown is caused by touching the pages.
IIRC you
> will encounter a sweep every time you touch a pod page and the cache
is
> exhausted. The sweep should reap all zeroed pages and hopefully fill
the cache
> so the sweep should not be invoked too often. Try using the
non-touching
> allocator.
> 

So avoiding the sweep is the thing to do then?

Where does the sweep start? Does it sweep in physical address order from
lowest address to highest? If I allocated some memory with a low
physical address and zero'd it and then didn't touch it would that be
found first?

Alternatively, I balloon down 1MB of memory at a time - if I could set
aside 1MB of memory that was filled with 0's and could somehow tell xen
to use that memory first then it might speed things up too yes?

Thanks

James

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