Re: An idea for prefetching swapped memory...
Jörn Engel (firstname.lastname@example.org)
Mon, 7 Apr 2003 14:43:12 +0200
On Mon, 7 April 2003 14:32:26 +0200, David Zaffiro wrote:
> >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
> Wouldn't it cost almost twice as much when the user requests a different
> task, instead of the just swaped-in "last swaped-out task(s)"?!
> Instead of loading this directly into a free portion of phys. memory, the
> just-swapped-in-ex-swapped-out task(s) would need to be swapped-out *again*
> in favour of the to-be-swaped-in task...
> Or am I wrong here?
Partially. If done right, the swapout would simply free those pages.
The information is already on the disk and unchanged, after all.
If you're willing to restrict the flexibility of your approach,
you can almost always do something better.
-- John Carmack
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