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cudaconstantsdimensions
einpoklum
einpoklum

Reputation: 131547

CUDA grid dimension maxima - where are they defined?

The CUDA programming guide gives non-device-specific maxima for grid dimensions in blocks: 2^31 - 1 for the x dimension, 2^16 - 1 for the y and z dimensions (table 15, as of CUDA 11.3).

My question: Where are these values defined, in code? I also looked at the driver API entry on cudaLaunchKernel, and it doesn't mention such constants either. I searched for 65535, for "<< 16" and for "<<16" in the CUDA header files, and no luck there either.

Upvotes: 0

Views: 120

Answers (1)

Robert Crovella
Robert Crovella

Reputation: 151869

They are not defined in code. They are a property of the device, the checking is at runtime (this is easily demonstrable), and the checking is done against properties retrieved from the device in question.

You can study the deviceQuery sample code to see how it might work.

Upvotes: 3

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