Vax C90-EL SERIES Service Manual download pdf (Page 38)

Cray Standard C/C++ Reference Manual

Note: The MSP is an optional feature. To determine whether the 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(1) man page.

2.9.1 -h streamn (CC, cc) (Cray SV1 Series Systems Only)

The -h streamn option specifies the level of automatic 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:

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.

2.10 Vector Optimization Options

The following sections describe vector optimization options.

2.10.1 -h [no]infinitevl (CC, cc)

Default option: -h noinfinitevl

The -h infinitevl option instructs the compiler to assume an infinite safe

vector length for all #pragma ivdep directives. The -h noinfinitevl option

instructs the compiler to assume a safe vector length equal to the maximum

supported vector length on the machine for all #pragma ivdep directives.

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Vax C90-EL SERIES Service Manual Page 38