3.1 Automatic Parallelization Using the kf77 Driver

Automatic parallelization is most useful on large programs with the following characteristics:

• The loops are obviously parallelizable.

• You are unfamiliar with the code.

KAP is unable to automatically parallelize loops with data dependencies between loop iterations or loops with calls to external routines. You may be able to cause KAP to parallelize such loops by using C*$* assertions and directives to give KAP more information.

To compile a program for automatic parallel execution, use the KAP -concurrentize switch, abbreviated -conc , with the kf77 driver, as follows:

kf77 -fkapargs='-conc' myprog.f

The -conc switch tells KAP to automatically restructure code for parallel processing. When you use the -conc switch with the kf77 command, the driver sets the compiler switch -automatic by default to ensure correct execution of a multithreaded program. Do not override the - automatic switch.

The -conc switch causes the kf77 driver to set the correct linker switches for your versions of the DIGITAL UNIX parallel run-time and DECthreads libraries. For example, the -conc switch sets the following DIGITAL UNIX compiler and linker switches:

• -automatic

• -fast

• -lkmp_osf or -lkmp_osfp10

• -threads or -pthread

• -call_shared

• -tune host

Section 3.4 explains these switches.

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