Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!cs.utexas.edu!uwm.edu!lll-winken!vette!brooks
From: brooks@vette.llnl.gov (Eugene Brooks)
Newsgroups: comp.arch
Subject: Re: ATTACK OF KILLER MICROS
Message-ID: <35897@lll-winken.LLNL.GOV>
Date: 15 Oct 89 18:30:11 GMT
References: <35825@lll-winken.LLNL.GOV> <2121@brazos.Rice.edu>
Sender: usenet@lll-winken.LLNL.GOV
Reply-To: brooks@maddog.llnl.gov (Eugene Brooks)
Organization: Lawrence Livermore National Laboratory
Lines: 26

In article <2121@brazos.Rice.edu> preston@titan.rice.edu (Preston Briggs) writes:
>In article <35825@lll-winken.LLNL.GOV> brooks@maddog.llnl.gov () writes:
>>The best of the microprocessors now EXCEED supercomputers for scalar
>>performance and the performance of microprocessors is not yet stagnant.
>
>Is this a fair statement?  I've played some with the i860 and
Yes, in the sense that a scalar dominated program has been compiled for
the i860 with a "green" compiler, no pun intended, and the same program
was compiled with a mature optimizing compiler on the XMP, and the 40MHZ
i860 is faster for this code.  Better compilers for the i860 will open
up the speed gap relative to the supercomputers.

>I can write (by hand so far) code that is pretty fast.
>However, the programs where it really zooms are vectorizable.
Yes, this micro beats the super on scalar code, and is not too sloppy
for hand written code which exploits its cache and pipes well.  The
compilers are not there yet for the vectorizable stuff on the i860.
Even if there were good compilers, the scalar-vector speed differential
is not as great on the i860 as it is on a supercomputer.  Of course,
interleaved memory chips will arrive and microprocessors will use them.
Eventually the high performance micros will take the speed prize for
vectorizable code as well, but this will require another few years of
development.


brooks@maddog.llnl.gov, brooks@maddog.uucp