Essentials

Initialization

CUDA.functional — Method
functional(show_reason=false)

Check if the package has been configured successfully and is ready to use.

This call is intended for packages that support conditionally using an available GPU. If you fail to check whether CUDA is functional, actual use of functionality might warn and error.

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CUDA.has_cuda — Function
has_cuda()::Bool

Check whether the local system provides an installation of the CUDA driver and runtime. Use this function if your code loads packages that require CUDA.jl. ```

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CUDA.has_cuda_gpu — Function
has_cuda_gpu()::Bool

Check whether the local system provides an installation of the CUDA driver and runtime, and if it contains a CUDA-capable GPU. See has_cuda for more details.

Note that this function initializes the CUDA API in order to check for the number of GPUs.

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Global state

CUDA.context — Function
context(ptr)

Identify the context memory was allocated in.

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context()::CuContext

Get or create a CUDA context for the current thread (as opposed to current_context which may return nothing if there is no context bound to the current thread).

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CUDA.context! — Function
context!(ctx::CuContext)
context!(ctx::CuContext) do ... end

Bind the current host thread to the context ctx. Returns the previously-bound context. If used with do-block syntax, the change is only temporary.

Note that the contexts used with this call should be previously acquired by calling context, and not arbitrary contexts created by calling the CuContext constructor.

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CUDA.device! — Function
device!(dev::Integer)
device!(dev::CuDevice)
device!(dev) do ... end

Sets dev as the current active device for the calling host thread. Devices can be specified by integer id, or as a CuDevice (slightly faster). Both functions can be used with do-block syntax, in which case the device is only changed temporarily, without changing the default device used to initialize new threads or tasks.

Calling this function at the start of a session will make sure CUDA is initialized (i.e., a primary context will be created and activated).

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CUDA.device_reset! — Function
device_reset!(dev::CuDevice=device())

Reset the CUDA state associated with a device. This call with release the underlying context, at which point any objects allocated in that context will be invalidated.

Note that this does not guarantee to free up all memory allocations, as many are not bound to a context, so it is generally not useful to call this function to free up memory.

Warning

This function is only reliable on CUDA driver >= v12.0, and may lead to crashes if used on older drivers.

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CUDA.stream — Function
stream()

Get the CUDA stream that should be used as the default one for the currently executing task.

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CUDA.stream! — Function
stream!(::CuStream)
stream!(::CuStream) do ... end

Change the default CUDA stream for the currently executing task, temporarily if using the do-block version of this function.

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