The STREAM Tests

The STREAM tests are exercising simple instructions on arrays larger than the CPU's cache. The memory access is mostly sequential. The results are illustrative for raw speed of CPU/Cache/RAM on large problems.

We run the standard version of the tests that allow comparison with other systems (please see the data on the STREAM website), and a modified version with a much larger footprint.  The results are represented as memory bandwidth (MB/s).

STREAM standard benchmarks (45.8 MB of RAM)

copyst

Scale_Standard

Add_Standard

Triad_Standard



Large STREAM
( 457.8 MB of RAM)

Copy_large

Scale_Large

Add_Large

Triad_Large


Observations

The memory bandwidth doesn't depend too much of the OS (as expected).

It looks like the STREAM tests are a good indication of the FSB "speed". The older Xeon 533 FSB CPU has about 66% of the bandwidth of the newer 800 FSB Xeon (as expected).

P4 performance seems to increase with the file size while Xeons seem to do slightly worse (unexpected).

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Comments and suggestions to: Florin Manolache | florin@andrew.cmu.edu