Re: Page aging broken in 2.6

[Manfred Spraul]

Ben wrote:

> I can imagine that an architecture with TLBs will usually evict
> the entry from the TLB sooner or later and the accessed bit will end
> up beeing set again. On PPC, that isn't the case, the entry can well
> stay a loooong time in the hash and if not evicted, _PAGE_ACCESSED
> will never be set again.
One risk for i386 are the huge tlbs that AMD uses (512 entries?) - hot 
pages might stay in the TLB forever.

> Or does it snoop accesses
> to the PTE to "catch" somebody clearing the bits ?
No. AMD K8 cpu partially snoop PDE/PTE accesses and ignore tlb flush 
instructions if they are certain that the tlb is valid, but I'm not 
aware that anyone snoops the complete tlb cache.

--
   Manfred

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