Re: [PATCH 0/8] idle page tracking / working set estimation

On Tue, Sep 27, 2011 at 3:03 AM, Balbir Singh [off-list ref] wrote:

On Sat, Sep 17, 2011 at 9:09 AM, Michel Lespinasse [off-list ref] wrote:

quoted

Patch 3 introduces page_referenced_kstaled(), which is similar to
page_referenced() but is used for idle page tracking rather than
for memory reclaimation. Since both functions clear the pte_young bits
and we don't want them to interfere with each other, two new page flags
are introduced that track when young pte references have been cleared by
each of the page_referenced variants.

Sorry, I have trouble parsing this sentence, could you elaborate on "when"?

page_referenced() indicates if a page was accessed since the previous
page_referenced() call.

page_referenced_kstaled() indicates if a page was accessed since the
previous page_referenced_kstaled() call.

Both of the functions need to clear PTE young bits; however we don't
want the two functions to interfere with each other. To achieve this,
we add two page bits to indicate when a young PTE has been observed by
one of the functions but not by the other.

-- 
Michel "Walken" Lespinasse
A program is never fully debugged until the last user dies.

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