71 lines
2.3 KiB
ReStructuredText
71 lines
2.3 KiB
ReStructuredText
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.. _cccl-runtime-stream:
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Streams
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========
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Stream is conceptually a queue of operations for a specific device. It is passed as an argument to all asynchronous operations like kernel launch, memory copy and allocations.
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:cpp:class:`cuda::stream_ref`
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-------------------------------
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.. _cccl-runtime-stream-stream-ref:
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:cpp:class:`cuda::stream_ref` is a non-owning wrapper around a ``cudaStream_t``. It prevents unsafe implicit constructions from
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``nullptr`` or integer literals and provides convenient helpers for:
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- ``sync()``: wait for the recorded work to complete
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- ``is_done()``: non-blocking completion query
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- comparison operators against other :cpp:class:`cuda::stream_ref` or ``cudaStream_t``
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Availability: CCCL 2.2.0 / CUDA 12.3
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Example:
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.. code:: cpp
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#include <cuda/stream>
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cudaStream_t stream;
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cudaStreamCreate(&stream);
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cuda::stream_ref ref{stream};
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ref.sync(); // synchronizes the stream via cudaStreamSynchronize
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assert(ref.is_done()); // verifies that the stream has finished all operations via cudaStreamQuery
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// compare against other stream_ref or cudaStream_t
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assert(ref == stream);
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assert(ref != cuda::invalid_stream);
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cudaStreamDestroy(stream);
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:cpp:struct:`cuda::stream`
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---------------------------
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.. _cccl-runtime-stream-stream:
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:cpp:struct:`cuda::stream` is an owning wrapper around a ``cudaStream_t`` that manages the lifetime of the underlying CUDA
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stream.
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It derives from :cpp:class:`cuda::stream_ref`, provides all of its functionality, and can be used anywhere a
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:cpp:class:`cuda::stream_ref` is expected.
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It can be constructed for a specific :cpp:class:`cuda::device_ref`, moved (but not copied), and converted from or to a
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``cudaStream_t`` via ``from_native_handle``/``release()``.
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Constructing a new :cpp:struct:`cuda::stream` always creates a non-blocking stream; see
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:ref:`non-blocking stream creation <cccl-runtime-cudart-non-blocking-streams>` for CUDA Runtime interop details.
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Availability: CCCL 3.1.0 / CUDA 13.1
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.. code:: cpp
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#include <cuda/stream>
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#include <cuda/devices>
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int main() {
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{
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// Create a stream on a specific device
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cuda::stream s{cuda::devices[0]};
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// Pass to a stream-ordered API
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// Synchronize the stream
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s.sync();
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} // Stream is automatically destroyed here
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}
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