Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!sdd.hp.com!zaphod.mps.ohio-state.edu!sol.ctr.columbia.edu!emory!hubcap!gdburns From: gdburns@osc.edu Newsgroups: comp.parallel Subject: Re: Critical Issues in Distributed-Memory Multicomputing. Message-ID: <12051@hubcap.clemson.edu> Date: 3 Dec 90 21:54:29 GMT Sender: fpst@hubcap.clemson.edu Organization: Ohio Supercomputer Center, Columbus, OH, USA Lines: 76 Approved: parallel@hubcap.clemson.edu In-Reply-To: <12027@hubcap.clemson.edu> > > The Distributed-Memory Multi-Computers have now been facilitated in >many research institutions and Universities. The most exciting time of >... >engineering usage. The software is always a vital problem for any >parallel computers, and is particularly a problem for multicomputers. > There seems still much to be done in this area. And many researchers >are numerical scientists who develop parallel algorithms for such >machines. The software problem and programming are given less attention >to. >... >for an endless variaty of applications. When could usual engineer >(not computer engineer) can use such machine with ease? > >Jingwen Wang I am willing to take a shot at this. I have been working on infrastructure s/w for multicomputers since '84 and I should first say that the situation has improved dramatically since then. I think we need four things for multicomputers to work: a) h/w, b) infrastructure s/w (compilers, comm/sync libraries and OS), c) algorithms (embodied in libraries not just papers) and d) education. H/W is in reasonable shape. Witness Touchstone, Intel, Ncube, office buildings full of incredible workstations and decent networks, and the easy to buy and build transputers. Infrastructure s/w, which I'll just call OS, doesn't get enough attention from the vendors, in my opinion, because the customer tends to look at either the glamour of the h/w or the bottom line application. OS doesn't get enough attention from academia because, IMHO, the work that needs to be done is grunt level - essentially big D and very little r. Algorithms are going well, I think, because of the number of people doing work. Getting the work productized and distributed is not going so well. I have not done a survey but I'm sure you could find a workable algorithm for every solver somewhere in the literature. In some cases you can find several alternatives. Education is the kicker. You have to learn how to program distributed memory. There are no true magic pills. It is not hard to learn but if you assume you don't have to learn anything or you expect to throw a switch and make the whole thing go faster, you're in trouble. Back to OS, I think that we need to get out our hammer and saw and build a quality lifestyle on multicomputers. Quality to me means: 1) a dynamic multi-tasking environment on every node 2) a powerful, no-nonsense, save the pardigms for later, support everything message passing system on every node 3) Unix file access in all its glory from every node 4) lots of control (user is boss not servant) and monitoring What we are used to for OS is a black box of nodes with performance as goal one and there is no goal two. Now we are taking the other extreme and putting Mach and Unix friends on every node. If scalable scientific computation is the goal, I believe this is overkill. I don't blame the vendors who do what the market and the bottom line dictates. I don't blame academia who have to publish or die. There just aren't many places that can afford to engineer nuts and bolts software. I think MIMDizer and F90 are logical next steps in multicomputer tool technology. I/O and comm libraries like CrOS and Cubix are also very good. Linda and Strand are, IMHO, appropriate for functional parallelism. These things make multicomputer programming sensible and even fun. But not enough effort has been spent on open environments with process control/status, message status, error code delivery, and other mundane support whose absence can really ruin your day. --Greg -- Greg Burns gdburns@tbag.osc.edu Trollius Project (614) 292-8492 Research Computing The Ohio State University Brought to you by Super Global Mega Corp .com