Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!wuarchive!gem.mps.ohio-state.edu!uakari.primate.wisc.edu!uflorida!stat!stat.fsu.edu!mccalpin From: mccalpin@masig3.ocean.fsu.edu (John D. McCalpin) Newsgroups: comp.arch Subject: Re: ATTACK OF KILLER MICROS Message-ID: Date: 18 Oct 89 14:39:33 GMT References: <35825@lll-winken.LLNL.GOV> <1081@m3.mfci.UUCP> <35896@lll-winken.LLNL.GOV> Sender: news@stat.fsu.edu Organization: Supercomputer Computations Research Institute Lines: 51 In-reply-to: brooks@vette.llnl.gov's message of 15 Oct 89 18:20:48 GMT In article <35896@lll-winken.LLNL.GOV> brooks@maddog.llnl.gov (Eugene Brooks) writes: >Supercomputers of the future will be scalable multiprocessors made of >many hundreds to thousands of commodity microprocessors. They will be >commodity parts because these parts will be the fastest around and >they will be cheap. These scalable machines will have hundreds of >commodity disk drives ganged up for parallel access. Commodity parts >will again be used because of the cost advantage leveraged into a >scalable system using commodity parts. The only custom logic will be >the interconnect which glues the system together, and error correcting >logic which glues many disk drives together into a reliable high >performance system. The CM data vault is a very good model here. I think that it is interesting that you expect the same users who can't vectorize their codes on the current vector machines to be able to figure out how to parallelize them on these scalable MIMD boxes. It seems to me that the automatic parallelization problem is much worse than the automatic vectorization problem, so I think a software fix is unlikely.... In fact, I think I can say it much more strongly than that: Extrapolating from current experience with MIMD machines, I don't think that the fraction of users that can use a scalable MIMD architecture is likely to be big enough to support the economies of scale required to compete with Cray and their vector machines. (At least for the next 5 years or so). I *do* think is that the romance with vector machines has worn off, and people are realizing that they are not the answer to everyone's problems. This is a good thing --- I like it when people migrate their scalar codes off of the vector machines that I am trying to get time on!!! What is driving the flight from traditional supercomputers to high-performance micros is turnaround time on scalar codes. From my experience, if the code is really not vectorizable, then it is probably not parallelizable either, and scalable machines won't scale. These users are going to want the fastest single-processor micro available, unless their memory requirements are too big their ability to purchase. The people who can vectorize their codes are still getting 100:1 improvements going to supercomputers --- my code is over 500 times faster on an 8-cpu Cray Y/MP than on a 25 MHz R-3000/3010. So the market for traditional supercomputers won't disappear, it will just be more limited than many optimists have predicted. -- John D. McCalpin - mccalpin@masig1.ocean.fsu.edu mccalpin@scri1.scri.fsu.edu mccalpin@delocn.udel.edu