Streams Management

aclError aclrtCreateStream(aclrtStream *stream)

stream, ret = acl.rt.create_stream()

Creates a stream. It is a synchronous interface.

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stream: int, stream object pointer.

ret: int, error code.

• 0 indicates success.
• Other values indicate failure.

The hardware supports a maximum of 1024 streams. If there are multiple default streams, only explicit streams can be created. The number of allowed explicit streams is calculated as follows: 1024 – Number of default streams – Number of streams for internal synchronization. For example, if a default stream and a stream for internal synchronization exist, only 1022 (= 1024 – 1 – 1) streams can be created explicitly.

Each process corresponds to a default stream. The default stream is implicitly created when acl.rt.set_device is called to specify the device used for computation. The system reserves the default streams for a maximum of eight processes. You are advised to explicitly create a stream by calling acl.rt.create_stream.

• Implicitly created stream: It is applicable to simple applications without complex interaction logic. However, in multi-thread programming, the execution result depends on the thread scheduling sequence.
• (Recommended) Explicitly created stream: It is applicable to large-scale applications with complex interaction logic, improving application readability and maintainability.

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aclError aclrtDestroyStream(aclrtStream stream)

ret = acl.rt.destroy_stream(stream)

Destroys a specified stream. Only the streams created by calling acl.rt.create_stream can be destroyed. It is a synchronous interface.

stream: int, stream pointer to be destroyed.

ret: int, error code.

• 0 indicates success.
• Other values indicate failure.

• Before calling acl.rt.destroy_stream to destroy a specified stream, call acl.rt.synchronize_stream to ensure that all tasks in the stream are completely executed.
• When calling acl.rt.destroy_stream to destroy a specified stream, ensure that the stream is in the current context.
• When calling the acl.rt.destroy_stream API to destroy a stream, ensure that the stream is not being used by other APIs.

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