33 lines
1.3 KiB
Markdown
33 lines
1.3 KiB
Markdown
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[README](../../README.md#documentation) > **Dependent kernel launch**
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# Dependent kernel launches
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The Hopper architecture supports a new feature through which two kernels in the same stream can
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overlap their execution, named
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[Programmatic Dependent Launch (PDL)](https://docs.nvidia.com/cuda/cuda-c-programming-guide/index.html#programmatic-dependent-launch-and-synchronization).
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This allows kernels with conflict in global memory to programmatically and safely overlap portions
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of their execution. Primary kernel can signal it is about to finish execution, and the next kernel can
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optionally wait on the previous kernel to finish flushing its memory.
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For more information, we refer you to the [PDL section in the CUDA Programming Guide](https://docs.nvidia.com/cuda/cuda-c-programming-guide/index.html#programmatic-dependent-launch-and-synchronization).
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## Using dependent launch in CUTLASS
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When building CUTLASS, you can use the `CUTLASS_ENABLE_GDC_FOR_SM90` macro to
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enable PDL-related instructions in Hopper kernels:
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```
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cmake . -DCUTLASS_ENABLE_GDC_FOR_SM90=1
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```
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Note that this only adds PDL-related instructions to the _kernels_, but to actually allow a dependent
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launch, you must also run your GEMM kernel with PDL:
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```
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gemm.run(
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/* stream = */ stream,
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/* cuda_adapter = */ nullptr,
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/* launch_with_pdl = */ true
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);_
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```
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