Mmap a shared, anonymous region half the size of physical ram, fork a
hundred children, and let them start randomly writing in it. Now
put the children to sleep and start another process that pushes the
children into swap. Even when the active process goes away and the
children wake up, that is the last you'll ever see of your swap
(until the children die) because the chance that all 100 children
will happen to fault in any given page is miniscule.
Contrived? Sure, but you can bet somebody has a real load that acts
just like this. And *any* anonymous sharing is going to degrade the
effective size of your swap, the only variable is how much.
> Not to mention the superfluous IO being scheduled today.
Yes, well at this point we're suppose to demonstrate how much better
rmap does on that, are we not.
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