HP UX Fortran Software 6 Performance and optimization

LPATH environment variable.................................................................................................	65
MP_NUMBER_OF_THREADS environment variable.................................................................	65
Floating installation.................................................................................................................	65
Setting up floating installation..............................................................................................	66
3 Controlling data storage............................................................................	67
Disabling implicit typing..........................................................................................................	67
Automatic and static variables..................................................................................................	67
Increasing the precision of constants.........................................................................................	69
Increasing default data sizes....................................................................................................	70
Increasing default data sizes...............................................................................................	70
Sharing data among programs.................................................................................................	72
Modules vs. common blocks.....................................................................................................	74
4 Debugging..............................................................................................	76
Using the HP WDB debugger..................................................................................................	76
Stripping debugging information..............................................................................................	76
Handling runtime exceptions....................................................................................................	77
Bus error exception............................................................................................................	78
Floating-point exceptions.....................................................................................................	78
Illegal instruction exception.................................................................................................	79
Segmentation violation exception.........................................................................................	79
Bad argument exception.....................................................................................................	80
Using debugging lines............................................................................................................	80
5 Using the ON statement............................................................................	81
Exceptions handled by the ON statement..................................................................................	81
Actions specified by ON.........................................................................................................	82
Terminating program execution............................................................................................	83
Ignoring errors...................................................................................................................	83
Calling a trap procedure....................................................................................................	84
Trapping floating-point exceptions...................................................................................	84
Trapping integer overflow exceptions...............................................................................	84
Trapping +Ctrl-C trap interrupts................................................................................................	85
Allowing core dumps..............................................................................................................	85
6 Performance and optimization ...................................................................	87
Using profilers........................................................................................................................	87
HP Caliper........................................................................................................................	87
Invoking HP Caliper with the compiler to optimize your program.........................................	88
Comparing Program Performance....................................................................................	88
Using Options to Control Data Collection.........................................................................	89
Specifying PBO file names and locations..........................................................................	89
gprof................................................................................................................................	89
prof.................................................................................................................................	90
Using options to control optimization.........................................................................................	90
Using +O to set optimization levels......................................................................................	90
Using the optimization options.............................................................................................	91
Conservative vs. aggressive optimization...................................................................................	99
Parallelizing HP Fortran programs...........................................................................................	100
Compiling for parallel execution........................................................................................	100
Performance and parallelization.........................................................................................	101
Profiling parallelized programs..........................................................................................	101
Conditions inhibiting loop parallelization............................................................................	101
Calling routines with side effects parallellization .............................................................	101
Indeterminate iteration counts.......................................................................................	102
Data dependences......................................................................................................	102

4Contents