Sun 3 vs uVAXII floating point speed....

[Roy Smith]

ao at cevax.berkeley.edu (Akin Ozselcuk) writes:
> I am posting this article on behalf of a friend of mine who is planning
> to buy either a Sun3 or a VAX Station 2000 (a watered down uVAXII).  He
> is planning to do a lot of number crunching by using f77.

	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.

	By way of comparison, we have an 11/750 with FPA, 3/50s both with
and without 68881s and 3/160s with FPAs.  To give you some feel for the
rough relative speeds (notice the use of lots of ambigiuating terms; you're
mileage will vary depending on zillions of factors), we find that a 3/50
with 68881 and the 750 with FPA are roughly the same speed.  A 3/160 with
FPA is about 10 times faster than that.  From what I understand, the 3/260
(which we don't have) uses exactly the same FPA board as the 160 so for
floating-point intensive applications, the 260 is not a whole lot faster
than the 160.  My guess is that the uVAX-II is about the same speed as a
750.

	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.
-- 
Roy Smith, System Administrator
Public Health Research Institute
{allegra,philabs,cmcl2,rutgers}!phri!roy -or- phri!roy at uunet.uu.net
"The connector is the network"