[Beowulf] Win64 Clusters!!!!!!!!!!!!

Robert G. Brown rgb at phy.duke.edu
Wed Apr 11 00:37:52 EDT 2007


On Tue, 10 Apr 2007, Mark Hahn wrote:

>> It was PVM that enabled true message passing parallel code to be written
>> that made a pile of machines (be they Alphas, simple PCs, Sun
>
> I'm not disagreeing, but wonder why PVM is basically extinct now.
> that is, why was MPI considered an improvement/replacement?

Be careful.  Last time I suggested it was "basically extinct", this was
(somewhat forcefully) pointed out to me:

    http://pvmmpi07.lri.fr/

As of last year, there were still quite a lot of papers on PVM.  I think
PVM is still widely used in Europe, and a lot of "old hand" cluster
people, myself included still prefer it (given their druthers).  It is
much more a part of the ORIGINAL beowulfs and related linux clusters
than MPI.

MPI had a completely distinct history:

   www.csm.ornl.gov/pvm/PVMvsMPI.ps

It was developed first for real supercomputers, and only ported to COTS
TCP/IP clusters (with a "network" communications channel being
introduced) once TCP/IP clusters had been "invented" (noting well that
the first TCP/IP cluster probably postdated the invention of TCP/IP by
about fifteen minutes:-) and were regularly being built (mostly to run
EP or PVM programs).

PVM was from the beginning about being able to configure and control a
"virtual machine" -- the core idea behind the original beowulf, by the
way.  MPI was intended to be a parallel programming library to run on an
existing big iron system which required no "configuration" (e.g. node
selection or other VM setup).  They differ fairly strongly today in
these arenas, although of course time and open source has reduced the
differences.

MPI's two primary "advantages" over time have been -- much better vendor
support for native (non-TCP/IP) advanced network devices (PVM at one
point had a native myrinet driver IIRC, but pretty much could never run
any of the other advanced networks except as TCP/IP networks, which
added a pretty huge latency hit per message from the TCP stack); a
larger code base inherited from the old big iron supercomputers and more
programmers moving from those supercomputers who were skilled at coding
in it.  More recently it sounds (from list discussions) like MPI has
also gained some real technical advantages in the actual library
internals, but you'd need to ask an MPI expert for an opinion there, not
me.

>> MS knifed IBM over OS/2 (which was a decently designed OS that might
>> have given Unix a real run for its money) and hence lost out on all the
>
> I worked on OS/2, and it was no peach on the inside, so to speak ;)
> it's hard to speculate about what-ifs on a system which had barely
> shaken off its initial hw target (12 MHz 286!) by the time it was dropped.

People I knew down here who worked on it (out in the park) thought
pretty highly of it (probably about 2.0 or later versions of it -- the
early 286-only versions were pretty rough as I understand it) but I
myself never used it or NT -- I used Win 3.[0,1,2] at home, and while I
used Win 95 for a brief time a) it sucked; b) I'd long been using and
adminstering Unix networks, and had started using linux at home.

Mind you, linux only ran with infinite pain on my small-memory 486 -- I
barely could get slackware installed on an 8 MB system, although it
supposedly COULD be installed on 4 -- but I got an AMD 5 system with
(IIRC) 16 whole MB of memory and it ran charmlike on it.  It did not
suck -- it ran every bit as nicely as the Suns I had been using for many
years at that point, and came with X and compilers and everything, for
free.  I never looked back.  So my "decently designed" is definitely
hearsay.

The "knifed" part is more than JUST hearsay, though -- I met a bunch of
IBMers at the Linux Expo over in Raleigh back in 1999 or thereabouts (I
was running the Extreme Linux booth, and met Doug and Forrest and a
bunch of other linux geek types there for the first time in human
person:-).  The IBMers HATED Microsoft, and were actually quite fond of
linux.  The reasons given were that MS had screwed IBM royally over
OS/2, costing lots of their friends their jobs and depressing a whole
section of the company.  Linux was perceived as being a long term road
to revenge -- as IBM gradually shrank down its residual OS/2 business
they were working to replace it with linux.  To this day, IBM is the
only company that I know of that has advertised linux on TV.

And then there is the MS settlement with IBM in an OS/2 antitrust action
($750 million, two years ago) where for that much money to exchange
hands in a SETTLEMENT, one imagines that there was ample evidence of
knife-wound blood -- so call it "heavily supported" hearsay.

     rgb

-- 
Robert G. Brown	                       http://www.phy.duke.edu/~rgb/
Duke University Dept. of Physics, Box 90305
Durham, N.C. 27708-0305
Phone: 1-919-660-2567  Fax: 919-660-2525     email:rgb at phy.duke.edu


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