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From: brooks@vette.llnl.gov (Eugene Brooks)
Newsgroups: comp.arch
Subject: Re: superscalar
Message-ID: <26434@lll-winken.LLNL.GOV>
Date: 5 Jun 89 18:34:22 GMT
References: <26356@lll-winken.LLNL.GOV> <14FU029t326G01@amdahl.uts.amdahl.com>
Sender: usenet@lll-winken.LLNL.GOV
Reply-To: brooks@maddog.llnl.gov (Eugene Brooks)
Organization: Lawrence Livermore National Laboratory
Lines: 21

In article <14FU029t326G01@amdahl.uts.amdahl.com> mat@uts.amdahl.com (Mike Taylor) writes:
>In article <26356@lll-winken.LLNL.GOV>, brooks@maddog.llnl.gov writes:
>>                          ...  On a radiation transport Monte Carlo code,
>> which is something we routinely crunch on supercomputers like the XXXX
>> machines, that wimpy little XXX with an alpha compiler outran the
>> XXXX by 10% or so.
Please note that my posting contained a copyright notice which specifically
forbids excerpting such as this without including of the copyright.  I don't
mind excerpting sections of the posting which did not contain any reference
to specific vendors, but this type of excerpt MUST include the copyright.

>I presume this code doesn't vectorize well (or at all?)  What % vector
>is it on the Cray?  Just curious....

To answer the question, the code vectorizes with extreme recoding effort on
the Cray to get a factor of 5 in speed.  Parallel machines based on the
VLSI chips will still have a factor of 20 in cost and performance leverage
after this is taken into account.


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