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Subject: Re: [OMPI devel] Notes from mem hooks call today
From: Roland Dreier (rdreier_at_[hidden])
Date: 2008-05-28 19:09:42


> I think Patrick's point is that it's not too much more expensive to do the
> syscall on Linux vs just doing the cache lookup, particularly in the
> context of a long message. And it means that upper layer protocols like
> MPI don't have to deal with caches (and since MPI implementors hate
> registration caches only slightly less than we hate MPI_CANCEL, that will
> make us happy).

Stick in a separate library then?

I don't think we want the complexity in the kernel -- I personally would
argue against merging it upstream; and given that the userspace solution
is actually faster, it becomes pretty hard to justify.