Workload Scheduling

• In OpenMP, compiler accepts directives for work distribution:
  • C$OMP DO SCHEDULE(type[,chunk]) where type is
    • STATIC iterations are divided into pieces at compile time (default)
    • DYNAMIC iterations assigned to processors as they finish, dynamically. This requires synchronization after each chunk iterations.
    • GUIDED pieces reduce exponentially in size with each dispatched piece
    • RUNTIME schedule determined by an environment variable OMP_SCHEDULE With RUNTIME it is illegal to specify chunk. Example: setenv OMP_SCHEDULE “dynamic, 4”
  • If a directive does not mention the scheduling type, compiler switch -mp_schedtype=type can be used to set the scheduling type

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