Messages in this thread | | | Date | Tue, 19 Jan 1999 17:46:22 GMT | From | "Stephen C. Tweedie" <> | Subject | Re: swapout and pte_young() PG_referenced |
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Hi,
On Fri, 15 Jan 1999 17:37:00 +0100 (CET), Andrea Arcangeli <andrea@e-mind.com> said:
> I can see why we return 0 and we mark the page old in the swapout young > case.
> But I can't see how can be useful marking the page PG_referenced before > return 0 if the page is young. It's not a swap cache page, it's not a > freeable page and shrink_mmap() can do nothing with it.
> Am I missing something again ? ;)
Yes. We might well have released the page before shrink_mmap() next comes around to it. Think about a binary which exits and is respawned. We want any usage information (the PG_referenced bit) to survive the exit() so that it is not immediately evicted from cache once the process exits and shrink_mmap starts taking an interest in it.
--Stephen
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