Re: Remote fork() and Parallel programming
Perry Harrington (pedward@sun4.apsoft.com)
Sun, 14 Jun 1998 15:42:44 -0700 (PDT)
>
> : It seemed wiser to write my software for MPI and deal with the
> : difficulties and it being non-optimum on my smp system. (Although I've
> : never tested it, I'm sure that shared memory on a smp system is *MUCH*
> : faster then MPI)...
>
> Actually, only if you don't do anything to the MPI libraries. I.e., they
> are doing networking through the loopback device.
>
> SGI took the libs, gutted 'em, leaving just the interfaces, and tuned them
> especially for SMP machines (yeah, they can still call out to the networking
> ones when they need to).
>
> They even did some VM hacking such that they could map another process'
> address space so that a send() turned into
>
> find the process associated with the destination
> make we've already mapped the destination
> bcopy()
>
> It was damn close to no more than the bcopy() cost.
IIRC, Unix domain sockets are implemented as a memory passing scheme. Since a
UDS would conceivably be less resource intensive than actually doing a lookup
PID, find the VMA, then copy, perhaps the energy would be better spent
optimizing that functionality?
--Perry
--
Perry Harrington Linux rules all OSes. APSoft ()
email: perry@apsoft.com Think Blue. /\
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