O.k.  Then the code definitely needs to handle shared mappings..

Why? we just divided the pagetable size by a factor of 1000, so
the problem is no longer really there ;-)
 

quoted

Well, in theory there's some kind of TLB benefit, but the only thing
ppl really care about is x86 pagetable structure gets rid of L3 space
entirely so you don't burn 12+GB of L3 pagetables for appserver loads.

I am with the group that actually cares more about the TLB benefit.
For HPC loads there is really only one application per machine.  And with
just one page table, the only real advantage is the more efficient use
of the TLB.  

The reason we don't see it much is that we mostly have P3's which only
have 4 entries for large pages. P4's would be much easier to demonstrate
such things on, and I don't think we've really tried very hard on that with
hugetlbfs (earlier Java work by the research group showed impressive
improvements on an earlier implementation).

M.

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