Re: [PATCH 11/11] KVM: MMU: improve write flooding detected

On Fri, Aug 26, 2011 at 11:18:01AM +0800, Xiao Guangrong wrote:

On 08/25/2011 09:47 PM, Marcelo Tosatti wrote:

quoted

I guess it is OK to be more trigger happy with zapping by ignoring
the accessed bit, clearing the flood counter on page fault.

Yeah, i like this way, is this patch good for you?

Looks fine, can you rerun kernbench?

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Subject: [PATCH 11/11] KVM: MMU: improve write flooding detected

Detecting write-flooding does not work well, when we handle page written, if
the last speculative spte is not accessed, we treat the page is
write-flooding, however, we can speculative spte on many path, such as pte
prefetch, page synced, that means the last speculative spte may be not point
to the written page and the written page can be accessed via other sptes, so
depends on the Accessed bit of the last speculative spte is not enough

Instead of detected page accessed, we can detect whether the spte is accessed
after it is written, if the spte is not accessed but it is written frequently,
we treat is not a page table or it not used for a long time

Signed-off-by: Xiao Guangrong <redacted>