Re: Populating multiple ptes at fault time

[Jeremy Fitzhardinge <jeremy@goop.org>]

Avi Kivity wrote:
>> Yes.  At worst Linux would underestimate the process RSS a bit
>> (depending on how many unsynchronized ptes you leave lying around).  I
>>   
>
> Not the RSS (that's pte.present pages) but the working set (aka active
> list).

Yep.

>> bet there's an appropriate pvop hook you could use to force
>> synchronization just before the kernel actually inspects the bits
>> (leaving lazy mode sounds good).
>>   
>
> It would have to be a new lazy mode, not the existing one, I think.

The only direct use of pte_young() is in zap_pte_range, within a
mmu_lazy region.  So syncing the A bit state on entering lazy mmu mode
would work fine there.

The call via page_referenced_one() doesn't seem to have a very
convenient hook though.  Perhaps putting something in
page_check_address() would do the job.

    J