I have run the memory bandwidth code on a VAX 6000-410 equipped with a vector
processor running VMS 5.4-2. The memory bus has a theoretical peak of something
like 100MB/s. Unfortunately, there are usually a bunch of other users
on the machine so the timer I'm using (which measures wall time) varies a lot.
I tried to run the test in the morning when the system isn't very busy.
I had to make some changes in the code. I had to put a call to a dummy
subroutine after each timed loop, otherwise the compiler would optimize them
out. The timer routine was changed to use the secnds() routine rather than
etime. I also changed the size of the problem to 100000 because I didn't want
to hog too much memory on the system. The resulting working set size was a
couple of MB.
-----
compiled without using vector processor:
-------------------------------------
Double precision appears to have 17 digits of accuracy
Assuming 8 bytes per DOUBLEPRECISION word
-------------------------------------
Timing calibration ; time = 131.2500000000000 hundredths of a second
Increase the size of the arrays if this is <30
and your clock precision is =<1/100 second
---------------------------------------------------
unction Rate (MB/s) RMS time Min time Max time
ssignment: 12.4121 0.3580 0.1289 0.7383
caling : 8.9043 0.3653 0.1797 0.4922
umming : 9.1701 0.5277 0.2617 0.7578
AXPYing : 7.9792 0.5586 0.3008 0.8086
compiled using vector processor:
-------------------------------------
Double precision appears to have 17 digits of accuracy
Assuming 8 bytes per DOUBLEPRECISION word
-------------------------------------
Timing calibration ; time = 60.93750000000000 hundredths of a second
Increase the size of the arrays if this is <30
and your clock precision is =<1/100 second
---------------------------------------------------
unction Rate (MB/s) RMS time Min time Max time
ssignment: 58.5143 0.0375 0.0273 0.0703
caling : 58.5143 0.0485 0.0273 0.1016
umming : 61.4400 0.0669 0.0391 0.0977
AXPYing : 51.2000 0.0660 0.0469 0.0977
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