Tuning Fortran M Programs

When writing Fortran M programs, you should be aware that Version 2.0 of the compiler implements the following language features efficiently:

• Computation: Sequential code is not modified by the Fortran M preprocessor and is compiled with conventional Fortran compilers.

• Communication: Preliminary experiments show that interprocessor communication rates are competitive with those achieved by message-passing libraries such as P4 and PVM.

In contrast, the following features are not implemented efficiently in Version 2.0 (but will be in future releases):

• Process Creation: The cost of creating a new Fortran M process is relatively high: over 100 msec on a Sun Sparcstation.

• Port Migration: The cost of sending a port from one process to another is relatively high: over 100 msec on Sun Sparcstation.

• Intraprocessor Communication: Intraprocessor (two processes on the same processor) communication performance is comparable to interprocessor communication performance on most machines. (On the SparcStation, it appears to be much less efficient for messages over 4k bytes.)