Here is the latest version of the swap prefetching patch. This code is now 
considered quite stable.

Changes:
-The longstanding bug which created swapcache pages that were pinned to ram 
and could only be removed by doing a swapoff was tracked down and fixed.
-Rate of free ram allocation is watched as an indirect and cheap method of 
determining if any significantly sized file reads are in progress.
-I/O priority support was added.
-The tunable to determine the amount of data retrieved per prefetch was added
/proc/sys/vm/swap_prefetch 
is used to decide how many groups of 128kb to prefetch per 1 second interval 
and is set to 2 by default. It can be disabled by setting it to 0

Incrementals and latest version available here:
http://ck.kolivas.org/patches/swap-prefetch/
(this is the same as the version in 2.6.13-ck7)

Cheers,
Con