Sun 3 vs uVAXII floating point speed....

[Guy Harris]

> 	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.