An idea for prefetching swapped memory...

[Thomas Schlichter <schlicht@uni-mannheim.de>]

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Hello,

some days ago some friends and me argued about a feature which seems not to be 
included in current OSs but could improve useability mainly for desktop 
computers.

The idea was about prefetching swapped out pages when some memory is free, the 
CPU is idle and the I/O load is low.

So this should not 'cost' much but behave better on following situation:
(I think there are even more such situations, this one should just be an 
example)

One is surfing the internet and having some browser windows opened. Now, 
without closing the browser windows, he is playing some game which needs 
pretty much memory so the browsers memory is getting swapped out. After 
finishing gaming he's going to make some coffee and then surfing the internet 
again.
But even if the computer was IDLE for a time and, as the game was closed 
again, some memory is really FREE, the pages for the browser are swapped in 
just when they are needed and not in advance.

With this feature there should be no performance decrease because only free 
resources would be used, and if pages were swapped in but not be used, they 
stay not dirty and so have not to be written to disk when they are swapped 
out again. But the improvements should be obvious if simply the last swaped 
out pages are swapped in again...

If somebody could give me a hint how to implement this I would try it. I hope 
it will not be very difficult... ;-)

Thank you for reading and perhaps thinking about it...

Best regards
   Thomas Schlichter

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