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Subject: Re: [OMPI devel] Memory hooks stuff
From: Patrick Geoffray (patrick_at_[hidden])
Date: 2008-05-25 10:54:23


Jeff Squyres wrote:
> That would also be great. I don't know anything about these mmu
> notifiers (I'm not much of a kernel guy), but anything that allows us

It's what Quadrics used for years in True64. Instead of trying to catch
at user-level all instances when the page table of a process is modified
(free, munmap, sbrk, etc...), the kernel notifies you when that happens.

The registration cache functionality would then move to each driver,
completely transparent for OpenMPI or any other user code.

> to get rid of the ugly hacks would be awesome. I assume that this
> would only be for very new/recent Linux kernels...? But even if you

Well, if Linux is not a dictatorship, this "UTTER AND TOTAL CRAP" would
be in 2.6.27 :-)

> So to be clear: I'm not proposing that we ditch ptmalloc and replace
> it with mallopt. I'm proposing that we have both ptmalloc and
> mallopt, and the user can choose which to use. And if some upcoming

I guess I am missing something, but let's defer this discussion for the
call.

Patrick