🚀 go-pugleaf

In article <35825@lll-winken.LLNL.GOV> brooks@maddog.llnl.gov writes:

>mash@mips.com pointed out some important considerations in the issue
>of whether supercomputers as we know them will survive.  I thought
>that I would attempt to get a discussion started.  Here is a simple
>fact for the mill, related to the question of whether or not machines
>delivering the fastest performance at any price have room in the
>market.

>Fact number 1:
>The best of the microprocessors now EXCEED supercomputers for scalar
>performance and the performance of microprocessors is not yet stagnant.
>On scalar codes, commodity microprocessors ARE the fastest machines at
>any price and custom cpu architectures are doomed in this market.

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

This much has been fairly obvious for a few years now, and was made
especially clear by the introduction of the MIPS R-3000 based machines
at about the beginning of 1989. I think that this point is irrelevant
to the more appropriate purpose of supercomputers, which is to run
long (or large), compute-intensive problems that happen to map well
onto available architectures.

Both factors (memory/time and efficiency) are important here.  It is
generally not necessary to run short jobs on supercomputers, and it is
not cost-effective to run scalar jobs on vector machines.  On the
other hand, I have several codes that run >100 times faster on the
ETA-10G relative to a 25 MHz MIPS R-3000.  Since I need to run these
codes for hundreds of ETA-10G hours, the equivalent time on the
workstation is over one year.

The introduction of vector workstations (Ardent & Stellar) changes
these ratios substantially.  The ETA-10G runs my codes only 20 times
faster than the new Ardent Titan.  In this environment, the important
question is, "Can I get an average of more than 1.2 hours of
supercomputer time per day".  If not, then the Ardent provides better
average wall-clock turnaround.

It seems to me that the introduction of fast scalar and vector
workstations can greatly enhance the _important_ function of
supercomputers --- which is to allow the calculation of problems that
are otherwise too big to handle.  By removing scalar jobs and vector
jobs of short duration from the machine, more resources can be
allocated to the large calculations that cannot proceed elsewhere.

Enough mumbling....
--
John D. McCalpin - mccalpin@masig1.ocean.fsu.edu
		   mccalpin@scri1.scri.fsu.edu
		   mccalpin@delocn.udel.edu