[OpenMP] Support 'omp_get_num_procs' on the device #65501
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Summary: The `omp_get_num_procs()` function should return the amount of parallelism availible. On the GPU, this was not defined. We have elected to define this function as the maximum amount of wavefronts / warps that can be simultaneously resident on the device. For AMDGPU this is the number of CUs multiplied byth CU's per wave. For NVPTX this is the maximum threads per SM divided by the warp size and multiplied by the number of SMs.
shiltian
reviewed
Sep 6, 2023
| /// NVIDIA returns the product of the SM count and the number of warps that | ||
| /// fit if the maximum number of threads were scheduled on each SM. | ||
| uint64_t getHardwareParallelism() const override { | ||
| return HardwareParallelism; |
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This is borrowing it from a previous patch that was added for the RPC support. It's currently set at line 309.
shiltian
reviewed
Sep 6, 2023
| @@ -0,0 +1,15 @@ | |||
| // RUN: %libomptarget-compile-run-and-check-generic | |||
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You might want to require certain targets otherwise the test will fail since by default it returns 0.
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For x86 offloading this should use libomp.so's implementation, which should be supported.
avillega
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Sep 11, 2023
Summary: The `omp_get_num_procs()` function should return the amount of parallelism availible. On the GPU, this was not defined. We have elected to define this function as the maximum amount of wavefronts / warps that can be simultaneously resident on the device. For AMDGPU this is the number of CUs multiplied byth CU's per wave. For NVPTX this is the maximum threads per SM divided by the warp size and multiplied by the number of SMs.
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Summary:
The
omp_get_num_procs()function should return the amount ofparallelism availible. On the GPU, this was not defined. We have elected
to define this function as the maximum amount of wavefronts / warps that
can be simultaneously resident on the device. For AMDGPU this is the
number of CUs multiplied byth CU's per wave. For NVPTX this is the
maximum threads per SM divided by the warp size and multiplied by the
number of SMs.