Indirection arrays generally require expensive scheduling. By careful programming, one can reduce the number of schedules generated. Another technique that allows the compiler to optimize this type of communication is indirection array alignment. Another optimization that a programmer may use involves generating indirection arrays to reduce the use of expensive scalar communications. If you are comparing performance of an HPF program using several different algorithms, there are several relevant performance measurment parameters to use.
Parallel speedup measures the decrease in program execution time as more processors are added.
If is the time to execute the program with i processors, perfect speedup occurs when Another measure of speedup is the comparison of a program's parallel execution time with the execution time of an optimized sequential version of the program.