Re: Cray Results for bandwidth test

From: Andrew Zachary (
Date: Sun Sep 29 1991 - 12:32:50 CDT


For the test results I sent you, the compiler options were

        cf77 -Zv ....

i.e., I did not explicitly invoke the multitasking libraries. Now,
compiler and fpp may recognize SAXPY's and replace them
with the equivalent BLAS level 1 routines, which may be multitasked.
Since I did not run with setenv NCPUS 1, the multitasked routines
would have run on all 8 CPU's. However, I am skeptical, because
I ran your test several times, and each time I got the same
answers. Could there be a subtle error in your test?

As to the granularity of second, it should be good down to the
clock period - 6 nsec. Again, the answers differed only slightly
from run to run.

On Monday morning, when more machines are up, I'll try runnin your
test on a variety of Y-MP configurations.

Andrew Zachary
P.S. I'll also increase the loop length to 5,000,000 or so...

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