> I am, for example, very interested to see if Rik can get the overhead of
> the rmap stuff down low enough that it's not a noticeable hit under
> non-VM-pressure. I'm looking at the issue of doing COW on the page tables
> (which really is a separate issue), because it might make it more
> palatable to go with the rmap approach.
I'd be interested to know exactly how much overhead -rmap is
causing for both page faults and fork (but I'm sure one of
the regular benchmarkers can figure that one out while I fix
the RSS limit stuff ;))
About page table COW ... I've thought about it a lot and it
wouldn't surprise me if the 4 MB granularity of page tables
is too large to be of a real benefit since the classic path
of fork+exec would _still_ get all 3 page tables of the
typical process copied.
OTOH, it wouldn't surprise me at all if it was a win ;))
kind regards,
Rik
--
"Linux holds advantages over the single-vendor commercial OS"
-- Microsoft's "Competing with Linux" document
http://www.surriel.com/ http://distro.conectiva.com/
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