Optimization (Multi-Streaming Processor) (Deferred Implementation)

Cray C/C++ Reference Manual
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2.9. Optimization (Multi-Streaming Processor) (Deferred Implementation)

The following sections describe Multi-Streaming Processor (MSP) options. For information on MSP #pragma directives, see Section 4.9.

Note: MSP is an optional feature. To determine whether MSP is enabled on your system, enter the sysconf command at your system prompt. The HARDWARE output field contains the NMSP= field that shows the number of MSPs configured. For more information, see the sysconf man page.

2.9.1. `-h streamn` (`CC`, `cc` Commands)

(Cray SV1 systems) The -h streamn option specifies the level of automatic multi-streaming processing (MSP) optimizations to be performed. Generally, vectorized applications that execute on a 1-processor system can expect to execute up to 4 times faster on a processor with multi-streaming enabled.

Argument n can be one of the following:

n		Description
0		No automatic multi-streaming optimizations are performed.
1		Conservative automatic multi-streaming optimizations. Automatic multi-streaming optimization is limited to inner vectorized loops. MSP operations performed generate the same results that would be obtained from scalar optimizations; for example, no floating-point reductions are performed.
2		Moderate automatic multi-streaming optimizations. Automatic multi-streaming optimization is performed on loop nests.
3		Aggressive automatic multi-streaming optimizations. Automatic multi-streaming optimization is performed as with `stream2`.

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