Beowulf [& VMWare]

Donald Becker becker at scyld.com
Thu Nov 7 16:45:43 EST 2002


On 31 Oct 2002, Timothy H. Keitt wrote:
> On Thu, 2002-10-31 at 13:30, Donald Becker wrote:
> > 
> > As most list readers know, I consider Mosix to be an academically
> > interesting system and its transparent process migration an excellent
> > touchstone to compare process migration approachs.
> > 
> > Mosix is not a good system for scalable or performance-oriented
> > clustering, and I agree with your conclustion that Mosix+VMware
> > application serving is not a good match.
> 
> VMware aside, I'm not aware that openmosix precludes the use of mpi or
> pvm or standard batch processing. Are these not good solutions for
> scalable or performance-oriented clustering?

Mosix
   moves the migration policy into the kernel,
   has (deliberately) slow job migration to avoid scheduling hot-spots
   uses in-kernel communication forwarding

While these allow unaware, and unmodified, applications to be migrated,
they are exactly the wrong decisions for MPI and PVM applications.
MPI and PVM
   explicitly and simultaneously starts a known number of subprocesses,
   knows where those subprocesses should be, and
   builds new, explicit communication paths

The total effect is that Mosix takes much longer to start MPI/PVM jobs,
and has much higher overhead.

The features Mosix provides are
  single point application updates
  single process space view
Scyld Beowulf provides these at much lower CPU overhead.

-- 
Donald Becker				becker at scyld.com
Scyld Computing Corporation		http://www.scyld.com
410 Severn Ave. Suite 210		Scyld Beowulf cluster system
Annapolis MD 21403			410-990-9993

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