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Loop Work-sharing Construct: Schedule Clause
Dynamic [ , chunk ] |
- Fixed portions of work; size is controlled by the value of chunk
- When a thread finishes one chunk, It is dynamically assigned another
- The default chunk size is 1.
- Most work at runtime: complex scheduling logic used at run-time
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Guided [ ,chunk ] |
- Special case of dynamic to reduce scheduling overhead
- The size of the block starts large and shrinks down to size chunk as the calculation proceeds
- Default chunk size is 1
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Runtime |
- Iteration scheduling scheme is set at runtime through environment variable OMP SCHEDULE or the runtime library
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Questions |
Given loop of length 16 with 4 threads:
How the iterations will be assigned in static schedule with no chunk and chunk=2 ?
What will be the change in case of dynamic scheduling? |
Run-Time Library Routines
OMP SET NUM THREADS: Sets the number of threads that will be used in the next parallel region. Must be a positive number.
Format |
| void omp set num threads(int num threads) |
- This routine can only be called from the serial portion of the code.
- This call has precedence over the OMP NUM THREADS
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