Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!utgpu!water!watnot!watmath!clyde!rutgers!seismo!vrdxhq!verdix!ogcvax!pase From: pase@ogcvax.UUCP Newsgroups: comp.arch Subject: Re: Hypercubes (place in life) Message-ID: <1216@ogcvax.UUCP> Date: Thu, 26-Feb-87 15:34:29 EST Article-I.D.: ogcvax.1216 Posted: Thu Feb 26 15:34:29 1987 Date-Received: Sun, 1-Mar-87 10:37:39 EST References: <5699@amdahl.UUCP> <1210@ogcvax.UUCP> Reply-To: pase@ogcvax.UUCP (Douglas M. Pase) Organization: Oregon Graduate Center, Beaverton, OR Lines: 65 In article <1210@ogcvax.UUCP> pase@ogcvax.UUCP (Douglas M. Pase) writes: . . . However, machines like the iPSC were designed to do heavy computing, and NOT a lot of resource sharing. . . . The hypercube is set up to do number crunching, with lots of operations per byte of I/O. In article eugene@pioneer.UUCP (Eugene Miya N.) responds: Hypercubes were not designed to do a lot of heavy computing. You would be putting them into the Cray class of processor, and everyone's experience has been to the contrary. Agreed, the iPSC is not intended to compete with the Cray - at ~1 Mflop per 32 node tower, it hasn't near the horsepower of a Cray. Crays are especially good at problems which are vectorizable and require huge amounts of memory. The iPSC is not. (However, just try to pick up a Cray for under $200,000.) (Miya) Heavy computing requires a well thought out (balanced) structure to prevent things like an I/O bottleneck. A hypercube is far from a typical end-user machine. Again I agree, but whether a machine architecture is "balanced" or not depends alot on its intended application. If a huge volume of communication is required, the iPSC is probably not appropriate. Geoffrey Fox of CalTech presented a paper in one of the 1984 conferences extolling some of the virtues of a hypercube architecture (NOTE: NOT an iPSC - the iPSC is based on Fox's design) for computing. The article was called "Concurrent Processing for Scientific Calculations". It was in an IEEE conference, but I don't remember which one. BTW, just about any new architecture is "far from a typical end-user machine." (Miya) The marketing hype which has surrounded hypercubes astounds me. It turns out the ONLY person I have heard a level-headed response from was Justin Rattner of Intel who stated that these machines are research machines to provide exposure to people on the problems of doing parallel programming. Perhaps you're too easily astounded, or maybe you think it's of no use because it's of no use to you... (Miya) They are not designed to replace Crays or compete with them. To believe so would involve a great deal of misunderstanding. Again, I don't disagree - it was never my contention. (Miya) There are now five (if not more) companies selling hypercube architectures out there, I doubt if any will survive in the long term (in the hypercube market). Don't hold your breath for software either. Don't expect to take you dusty deck C or Fortran and have it automatically parallelize it (when it does, we will have achieved true AI 8-). No question but that algorithms for the iPSC require a different approach than Von Neumann style machines; hence dusty decks won't work. This is no suprise to me, as there is a big difference between an MIMD architecture and a SISD architecture, and only a little difference between vector/scaler and SISD architectures. Does that mean they'll never succeed? Well, we'll see... One Last Word: I'm glad you subscribe to this newsgroup Eugene; I enjoy your postings. Please keep them coming. -- Doug Pase -- ...ucbvax!tektronix!ogcvax!pase or pase@Oregon-Grad