Parallel Programming Guide for HP-UX Systems

UPC

Running

Chapter 5 101

Running

You can run UPC programs in one of three ways:

• Single-threaded execution

• Multithreaded execution on an AlphaServer SC system using the prun command

• Multithreaded execution on an SMP system (or on a single-CPU system) using the UPC

Run-Time Environment

Running programs in single thread mode

If a UPC program has been compiled with -fthreads set to 1, or without having speciﬁed a

value for -fthreads , then it may be run in single thread mode by simply executing the

program image directly, as with any normal UNIX program.

Single thread mode is useful for basic testing and debugging of UPC programs. Single thread

mode can be used on HP-UX or on Tru64 Unix Version 5.1 or later systems; the AlphaServer

SC software is not needed.

Running programs in multithread mode using Quadrics RMS

The prun (parallel run) command is included as part of the the software provided with the

AlphaServer SC system, and provides access to the Resource Management Services (RMS)

databases and system management services. For detailed information on the prun command,

refer to the reference page for prun and the RMS User Manual, provided with the

AlphaServer SC software documentation.

Example 5-1 prun

prun -n 4 upc_loadtest3

This command runs the executable program upc_loadtest3 in the default parallel partition,

using four threads, on four CPUs. All prun options can be used to run UPC programs on

whatever conﬁguration of CPUs and Nodes are desired. Output from each thread's stdout is

buffered and displayed at the terminal where the prun is executed. Diagnostics output to

stderr is not buffered---it is sent immediately and displayed at the same terminal.

If any inconsistencies are found, the UPCRTS issues a diagnostic message describing the

problem and exits before running the main function. (Inconsistencies are found in such areas

as: the declaration of a shared array in different modules; the value speciﬁed for -fthreads in

different modules; the value speciﬁed for -fthreads and the value used for the -n option to the