Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!mnetor!uunet!seismo!ll-xn!cit-vax!amdahl!littauer From: littauer@amdahl.amdahl.com (Tom Littauer) Newsgroups: comp.arch Subject: Re: What with these Vector's anyways? Message-ID: <10956@amdahl.amdahl.com> Date: Mon, 27-Jul-87 21:36:38 EDT Article-I.D.: amdahl.10956 Posted: Mon Jul 27 21:36:38 1987 Date-Received: Wed, 29-Jul-87 01:20:10 EDT References: <218@astra.necisa.oz> <142700010@tiger.UUCP> <363@astroatc.UUCP> <8344@utzoo.UUCP> <3636@well.UUCP> Reply-To: littauer@amdahl.UUCP (Tom Littauer) Organization: Amdahl Corp, Sunnyvale CA Lines: 31 In article <3636@well.UUCP> rchrd@well.UUCP (Richard Friedman) writes: >The best supercomputers are fast scalar machines first, with vector >processing hardware for additional speedup. Machines like the Cray X-MP >have a vector-to-scalar speedup factor of about 10. But their scalar >performance is faster than any conventional machine. !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! If the Dhrystone benchmarks are to be believed, this isn't the case. The May '87 report shows Cray X-MP at 18,530, and the IBM 3090-200 at 31,250. I'd mention our (much faster) machines, but that'd get perilously close to advertising :-). Nevertheless, the basic point is valid. If you could get it, you'd want a machine fast enough to do EVERYTHING quickly, not just a subset of things. This is not to demean the Cray machines: they do vectorizable work very quickly, but not all work is vectorizable. Until compilers are clever enough to make multithread/vector work out of work the programmer thinks of as serial, we're just gonna have to pick the right tool for the task at hand. End of pontification. -- -- UUCP: littauer@amdahl.amdahl.com or: {sun,decwrl,hplabs,pyramid,ihnp4,ames,seismo,cbosgd}!amdahl!littauer DDD: (408) 737-5056 USPS: Amdahl Corp. M/S 330, 1250 E. Arques Av, Sunnyvale, CA 94086 I'll tell you when I'm giving you the party line. The rest of the time it's my very own ravings (accept no substitutes).