From: "Paul R. Wilson" <wilson@cs.utexas.edu>
To: linux-mm@kvack.org
Subject: question about try_to_swap_out()
Date: Sun, 10 Jan 1999 21:38:46 -0600 [thread overview]
Message-ID: <199901110338.VAA19737@feta.cs.utexas.edu> (raw)
After checking that that a page is present and pageable, try_to_swap_out()
checks to see if the page is reserved or locked or not DMA'able when
where looking for a DMA page. If any of these three things is
true, it returns 0 without changing anything.
It seems to me that it should go ahead and check the pte age bit,
and update the page frame's PG_referenced bit, before returning 0.
One case I'm concerned about is a non-DMA page whose reference bit
doesn't get reset as usual. This page will still look recently-touched
at the next clock sweep, and that will make it stay cached longer,
just because we were looking for a DMA'able page when the clock
hand reached it this time.
I'm unclear what the significance is for a locked page.
Am I off-base here, or should the conditional that checks to see
whether a page is young (and updates the reference bits) be moved
up ahead of the conditional that checks to see whether a page
is (reserved | locked | not-dma-but-we-need-dma)?
Apologies if I'm way off base here.
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next reply other threads:[~1999-01-11 3:39 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
1999-01-11 3:38 Paul R. Wilson [this message]
1999-01-12 16:10 ` Stephen C. Tweedie
1999-01-12 16:58 Paul R. Wilson
1999-01-12 18:14 ` Stephen C. Tweedie
1999-01-14 10:15 ` ralf
1999-01-12 18:42 Paul R. Wilson
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