From: "Stephen C. Tweedie" <sct@redhat.com>
To: Rik van Riel <riel@nl.linux.org>
Cc: "Stephen C. Tweedie" <sct@redhat.com>,
Alan Cox <alan@lxorguk.ukuu.org.uk>,
ak@muc.de, ebiederm+eric@ccr.net, linux-kernel@vger.rutgers.edu,
linux-mm@kvack.org
Subject: Re: Q: PAGE_CACHE_SIZE?
Date: Sat, 29 May 1999 02:59:00 +0100 (BST) [thread overview]
Message-ID: <14159.18916.728327.550606@dukat.scot.redhat.com> (raw)
In-Reply-To: <Pine.LNX.4.03.9905282326100.19045-100000@mirkwood.nl.linux.org>
Hi,
On Fri, 28 May 1999 23:33:33 +0200 (CEST), Rik van Riel
<riel@nl.linux.org> said:
>> This has a lot of really nice properties. If we record sequential
>> accesses when setting up data in the first place, then we can
>> automatically optimise for that when doing the pageout again. For swap,
>> it reduces fragmentation: we can allocate in multi-page chunks and keep
>> that allocation persistent.
> Since we keep pages in the page cache after swapping them out,
> we can implement this optimization very cheaply.
It should be cheap, yes, but it will require a fundamental change in the
VM: currently, all swap cache is readonly. No exceptions. To keep the
allocation persistent, even over write()s to otherwise unshared pages
(and we need to do to sustain good performance), we need to allow dirty
pages in the swap cache. The current PG_Dirty work impacts on this.
--Stephen
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next prev parent reply other threads:[~1999-05-29 1:59 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
1999-05-18 14:03 Eric W. Biederman
1999-05-18 15:04 ` Andi Kleen
1999-05-19 23:29 ` Chris Wedgwood
1999-05-20 17:12 ` Andrea Arcangeli
1999-05-25 16:29 ` Alan Cox
1999-05-25 20:16 ` Rik van Riel
1999-05-25 22:17 ` Matti Aarnio
1999-05-27 22:06 ` Alan Cox
1999-05-28 20:46 ` Stephen C. Tweedie
1999-05-28 21:33 ` Rik van Riel
1999-05-29 1:59 ` Stephen C. Tweedie [this message]
1999-05-30 23:12 ` Andrea Arcangeli
1999-06-01 0:01 ` Stephen C. Tweedie
1999-06-01 14:23 ` Andrea Arcangeli
1999-05-29 15:07 ` Ralf Baechle
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