> What I wanted to say is that if there is free memory it should be filled with
> the pages that were in use before the memory got rare. And these are the pages
> swapped out last.
Not necessarily. Memory isn't merely used to hold swappable stuff, it also
caches files. Consider a small but io-intensive program. The stuff
you want isn't necessarily the last swap (perhaps there
even isn't anything swapped out) , it might be the last thing
dropped from cache instead.
And we can often predict better than "the last thing swapped/flushed"
A bunch of free memory appearing could usually be better used for
extra read-ahead, wether it is read-ahead of files/directories/bitmaps
being accessed, or executable code faulted in from executables or
> The other swapped out pages are swapped out even longer and so
> will likely not be used in the near future... (That's what the LRU algorithm
"What we're going to need soon" is the best. It isn't always predictable,
but sometimes. "The block following the last we read from some
is often a good one though.
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