Performance Studies using PSTSWM

SGI Origin2000 SWAP Performance

(unordered swap of 2MB message using SHMEM)

unordered swap using nonblocking send

Data Statistics bidirectional bandwidth estimated latency model error (peak MByte/sec) (usec/msg) (max. rel. error) 1 iter. 277.40 29.85 50.2% 10 iter. 668.02 8.49 37.0% 1 iter. w/overlap 306.28 -6.77 70.9% 10 iter. w/overlap 831.86 6.00 32.0%

unordered swap using nonblocking receive

Data Statistics bidirectional bandwidth estimated latency model error (peak MByte/sec) (usec/msg) (max. rel. error) 1 iter. 153.83 3.92 8.2% 10 iter. 650.67 8.11 39.7% 1 iter. w/overlap 308.42 8.40 4.2% 10 iter. w/overlap 862.40 4.82 33.2%

DISCUSSION

• An Origin2000 processing node consists of one or two processors. If two processors are in a node, they share the node's network interface hardware. It can be slower to exchange data between processors in the same node than between processors on different nodes (due to contention for shared resources?). For this reason, our SWAP experiments used logical processors 0 and 2 in a 4 processor partition.
• The experiments using multiple iterations show the effect of the improved memory locality intrinsic to the iteration logic, giving significantly better performance for the smaller message sizes. This is unlikely to be indicative of performance in real applications.

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Patrick H. Worley / ( worleyph@ornl.gov)
Last Modified Monday, 15-Jul-2002 10:07:04 EDT.
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