Re: [Xen-devel] map memory holes with same page

[Tim Deegan <Tim.Deegan@xxxxxxxxxx>]

At 09:42 +0100 on 23 May (1306143771), Paul Durrant wrote:
> > -----Original Message-----
> [snip]
> > 
> > Should there be a performance impact if Windows tries to touch a
> > page that I have previously given pack with decrease_reservation?
> > Will that invoke the PoD sweep?
> > 
> 
> No. The p2m entry will be 'invalid', not 'PoD'. IIRC the sweep should
> only be invoked if the cache is exhausted when trying to fix up a PoD
> entry.

But yes, there will be a performance impact because all accesses to the
missing page will be emulated by sending an ioreq to qemu, so it will
run _very_ slowly. 

Tim.

-- 
Tim Deegan <Tim.Deegan@xxxxxxxxxx>
Principal Software Engineer, Xen Platform Team
Citrix Systems UK Ltd.  (Company #02937203, SL9 0BG)

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