Re: [Xen-devel] PML (Page Modification Logging) design for Xen

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 16.02.15 at 12:44, <andrew.cooper3@xxxxxxxxxx> wrote:
> On 14/02/15 03:01, Kai Huang wrote:
>> To me looks currently tracking vram (HAP) shatters all superpages,
>> instead only superpages in vram range would be. Am I misunderstanding
>> here?
> 
> You are completely correct.
> 
> Having just re-reviewed the HAP code, superpages are fully shattered as
> soon as logdirty mode is touched, which realistically means
> unconditionally, given that Qemu will always track guest VRAM.  (So much
> for the toolstack trying to optimise the guest by building memory using
> superpages; Qemu goes and causes Xen extra work by shattering them all.)

So this is due to which code? I ask because I can't seem to be able
to spot it (p2m-ept.c uses ept_split_super_page() only on when
needed, not unconditionally everywhere)...

Jan


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