jlg (05/11/83)
Relay-Version:version B 3/9/83; site harpo.UUCP
Message-ID:<306@lanl-a.UUCP>
Date:Wed, 11-May-83 14:39:55 EDT
The sieve program used i BYTE was not really a very good benchmark of
larger machines. The problem is, there is too much stuff in the algorithm
that is not necessary (ie. never used or printed). A good compiler on a
large machine will probably 'optimize' all of this stuff out. The result
is that the same algorithm is not performed on each machine.
No one with access to both IBM and CRAY machines will really beleave that
the IBM numbers in the January BYTE are correct. The CRAY fortran numbers
(CFT is not very good at global optimization) are pretty accurate, also
a hand coded assembly version of the algorithm (which implements the whole
benchmark with nothing optimized out) beats the best IBM numbers by 50%.
The advantage of vector arch....
This may not seem to be relevant to the discussion of micros, but the newer
machines now and in the near future will be a lot more sophisticated than
those most micro fans are familiar with. Be on the lookout for bad benchmarks!
Mainframe people have had to face this problem many times.
J.L. Giles
(...!lasl-a!jlg)