Pros and Cons of OpenMP/MPI

• Pros of OpenMP
  
• easier to program and debug than MPI
  
• directives can be added incrementally - gradual parallelization
  
• can still run the program as a serial code
  
• serial code statements usually don't need modification
• code is easier to understand and maybe more easily maintained
• Cons of OpenMP
• can only be run in shared memory computers
  
• requires a compiler that supports OpenMP
• mostly used for loop parallelization
  

• Pros of MPI
  
• runs on either shared or distributed memory architectures
  
• can be used on a wider range of problems than OpenMP
  
• each process has its own local variables
  
• distributed memory computers are less expensive than large shared memory computers
  
• Cons of MPI
• requires more programming changes to go from serial to parallel version
• can be harder to debug
• performance is limited by the communcation network between the nodes