lamaster@ames.arc.nasa.gov (Hugh LaMaster) (06/27/88)
In article <7568@boring.cwi.nl> dik@cwi.nl (Dik T. Winter) writes: >Further: NEC SX (not IBM compatible) 128 or 256, depending on model, >with vector registers, like the Cray. This is the fastest supercomputer >in the world. According to the latest linpack benchmark, the Cray Y-MP, ETA-10E, and Cray X-MP with the latest compiler (CFT77 2.1) are, generally, faster single processors than the NEC SX-2, although the SX-2 wins the single processor matrix vector contest (anyone know why - I don't know the SX-2 architecture) -- Hugh LaMaster, m/s 233-9, UUCP ames!lamaster NASA Ames Research Center ARPA lamaster@ames.arc.nasa.gov Moffett Field, CA 94035 Phone: (415)694-6117
rchrd@well.UUCP (Richard Friedman) (06/28/88)
One reason why the NEC SX-2 does so well on matrix operations is that their compiler is one of the best!. See "Vectorizing Compilers: A Test Suite and Results" from Argonne (Tech Memo #109, March 31, 1988) from Dongarra, Callahan and Levine. It gives the results of running a large (100+) suite of routines thru a number of vectorizing compilers. Altho execution times are not given, (that WOULD be interesting!), they were only rating these compilers on their ability to vectorize/optimize source code. On a composite scale, the NEC compiler vectorize 59 out of 100 loops while CFT 1.15 did 51% and CFT77 did 52%. I should mention that the Alliant compiler did 71% and so did the Amdahl FORTRAN 77/VP. The FTN77 compiler on the ETA-10 did 69%. The point is that the NEC SX-2 runs faster than the X-MP in vector mode (clock is 6ns) so the more code you get into vector mode the better you are. I suppose that more loops in the LINPACK test were vectorized by the NEC compiler than the Cray. But thats just a guess. The SX-2 is a significant machine. -- ...Richard Friedman [rchrd] uucp: {ucbvax,lll-lcc,ptsfa,hplabs}!well!rchrd - or - rchrd@well.uucp