Deallocating memory pages

[Hiroshi Yamauchi]

Hi Bernd,

> I wonder if there is any deallocation cost involved at all. The VM can
> just mark the page as not-dirty and not-used. The only cost to use the
> page again (at the same place) would be to zero it. (and even that could
> be avoided if the VMM remembers the original owner and map it backl to the
> process if that process touches it again and no other process had the need
> for the page. Kind of same as buffer cache pages.

I'd not be surprised if it's the case (though I am not very familiar
with how the kernel or the VMM does things.)

>
> But I guess only some performance tests can answer that. (And add a test
> for large/hugepages to avoid automatic page splits if they are partially
> freed)

Right.