An idea for prefetching swapped memory...

[Thomas Schlichter]

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Hello,

some days ago some friends and me argued about a feature which seems not to=
 be=20
included in current OSs but could improve useability mainly for desktop=20
computers.

The idea was about prefetching swapped out pages when some memory is free, =
the=20
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=20
example)

One is surfing the internet and having some browser windows opened. Now,=20
without closing the browser windows, he is playing some game which needs=20
pretty much memory so the browsers memory is getting swapped out. After=20
finishing gaming he's going to make some coffee and then surfing the intern=
et=20
again.
But even if the computer was IDLE for a time and, as the game was closed=20
again, some memory is really FREE, the pages for the browser are swapped in=
=20
just when they are needed and not in advance.

With this feature there should be no performance decrease because only free=
=20
resources would be used, and if pages were swapped in but not be used, they=
=20
stay not dirty and so have not to be written to disk when they are swapped=
=20
out again. But the improvements should be obvious if simply the last swaped=
=20
out pages are swapped in again...

If somebody could give me a hint how to implement this I would try it. I ho=
pe=20
it will not be very difficult... ;-)

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

Best regards
   Thomas Schlichter
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