From: "Stephen C. Tweedie" <sct@redhat.com>
To: Rik van Riel <riel@nl.linux.org>
Cc: Kanoj Sarcar <kanoj@google.engr.sgi.com>, linux-mm@kvack.org
Subject: Re: filecache/swapcache questions
Date: Fri, 18 Jun 1999 00:33:30 +0100 (BST) [thread overview]
Message-ID: <14185.34250.163041.796165@dukat.scot.redhat.com> (raw)
In-Reply-To: <Pine.LNX.4.05.9906150930310.13631-100000@humbolt.nl.linux.org>
Hi,
On Tue, 15 Jun 1999 09:32:19 +0200 (CEST), Rik van Riel
<riel@nl.linux.org> said:
>> How will it be possible for a page to be in the swapcache, for its
>> reference count to be 1 (which has been checked just before), and for
>> its swap_count(page->offset) to also be 1? I can see this being
>> possible only if an unmap/exit path might lazily leave a anonymous
>> page in the swap cache, but I don't believe that happens.
> It does happen. We use a 'two-stage' reclamation process instead
> of page aging. It seems to work wonderfully -- nice page aging
> properties without the overhead.
Much more than that: if we take a write fault to a page which is shared
on swap by two processes, then we bring it into cache and take a
copy-on-write, leaving one copy in the swap cache (reference one: it is
_only_ in use by the swap cache now), and the other copy being reference
by the faulting process.
--Stephen
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next prev parent reply other threads:[~1999-06-17 23:33 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
1999-06-15 7:16 filecache/swapcache questions Kanoj Sarcar
1999-06-15 7:32 ` Rik van Riel
1999-06-15 15:51 ` Kanoj Sarcar
1999-06-15 20:24 ` Rik van Riel
1999-06-15 21:02 ` Kanoj Sarcar
1999-06-16 20:37 ` Andrea Arcangeli
1999-06-17 23:33 ` Stephen C. Tweedie [this message]
1999-06-18 0:20 ` Kanoj Sarcar
1999-06-18 17:00 ` Stephen C. Tweedie
1999-06-18 17:03 ` Kanoj Sarcar
-- strict thread matches above, loose matches on Subject: below --
1999-06-21 5:29 Kanoj Sarcar
1999-06-21 11:25 ` Stephen C. Tweedie
1999-06-21 16:46 ` Kanoj Sarcar
1999-06-21 16:57 ` Stephen C. Tweedie
1999-06-21 17:36 ` Kanoj Sarcar
1999-06-21 17:49 ` Stephen C. Tweedie
1999-06-21 18:46 ` Kanoj Sarcar
1999-06-21 23:44 ` Kanoj Sarcar
1999-06-24 22:23 ` Andrea Arcangeli
1999-06-24 23:55 ` Kanoj Sarcar
1999-06-25 0:26 ` Andrea Arcangeli
1999-06-28 22:36 ` Stephen C. Tweedie
1999-06-28 23:24 ` Kanoj Sarcar
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