Xref: utzoo comp.lang.fortran:912 comp.unix.questions:8226 Path: utzoo!attcan!uunet!seismo!sundc!pitstop!sun!gorodish!guy From: guy@gorodish.Sun.COM (Guy Harris) Newsgroups: comp.lang.fortran,comp.unix.questions Subject: Re: Sun 3 vs uVAXII floating point speed.... Message-ID: <59936@sun.uucp> Date: 14 Jul 88 18:09:32 GMT References: <25065@ucbvax.BERKELEY.EDU> <3381@phri.UUCP> Sender: news@sun.uucp Distribution: na Lines: 33 > Asking if a uVAX or a Sun-3 is faster for floating point is a > misleading question, or at least an imcomplete one. Are you talking about > a 3/50 without even the 68881 option or a 3/260 with FPA? The difference > in floating point speed between the two is at least an order of magnitude. His reference to 3 MIPS made it sound as if he were talking about a 3/60; the 3/60 comes standard with a 20MHz 68881 (faster than the 16.67MHz one for 3/50s and 3/100 series machines), but I don't think you can attach an FPA to it. As for the Sun386i, some tests I ran a while ago indicate that it may be faster on floating point than a 3/260 without an FPA, so it may well provide performance that's as good, if not better, than a 3/60. (The tests were just the Stanford benchmarks, I'm guessing what the 3/260 had, and the 386i wasn't running FCS software, so don't take my word for it.) > My guess is that the uVAX-II is about the same speed as a 750. My impression was that it was closer to a 780, but I've never used one so I don't know. > Another factor to consider is that Sun's new snazzy Fortran > compiler is supposed to produce *much* faster code than the generic Unix > f77 compiler. It does; it has a "real" optimizer (I'd say "global" except that I don't know how "global" it is; what is the "right" term for the generic sort of non-peephole optimizer?). It's not that "new" any more; in fact, in 4.0 on the Sun-2, Sun-3, and Sun-4, and in the Sun-4 Sys4-3.2 release, the same optimizer is available for the C compiler. I don't know whether it's available for FORTRAN or for C on the Sun386i. Now I think DEC may offer the VMS FORTRAN compiler on Ultrix as well, and that also has a "real" optimizer.