Memory Bandwidth

From: Michael Friedel (mfriedel@monolith.rmnug.org)
Date: Sat Nov 02 1991 - 22:52:13 CST


I converted your stream tests to C and ran them on my NeXT.

Here ar ethe results

Hardware:
NeXTStation Color, 12Meg
NeXTStep 2.1, with BSD 4.3 kernel

Compiler flags
-O

I tried all kinds of combinations, but they didn'y make a
difference. Note: Although the station has a 68040 it uses
68030 code.

Results

For double precision

Timing calibration: Time = 132.7215 hundredths of a second
Increase the size of the arrays if this is < 30 and your

clock precision is <= 1/100 second
Number of bytes per word = 8

Function Rate (MB/s) RMS time Min time Max time
Assignment : 14.2369 0.1079 0.3372 0.3582
Scaling : 11.4952 0.1357 0.4176 0.4599
Summing : 16.4071 0.1430 0.4388 0.4949
SAXPYing : 16.1239 0.1437 0.4465 0.4846

And for single precision

Timing calibration: Time = 60.2503 hundredths of a second
Increase the size of the arrays if this is < 30 and your

clock precision is <= 1/100 second
Number of bytes per word = 4

Function Rate (MB/s) RMS time Min time Max time
Assignment: 13.4077 0.0568 0.1790 0.1802
Scaling : 7.6574 0.0995 0.3134 0.3157
Summing : 10.5189 0.1085 0.3422 0.3438
SAXPYing : 8.4488 0.1350 0.4261 0.4275

Mike



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