Currently cuda version only supports training on a single GPU

[HenrySun98]

Description

I build LightGBM CUDA implementation, and set GPU parameter "device" : 'cuda' and "num_gpu" : 4
But I got a Fatal Error: Currently cuda version only supports training on a single GPU

In the official doc, it says multiple GPUs is supported in CUDA version.

My LightGBM version is : 4.0.0.99

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[HenrySun98]

Also, GPU parameter gpu_id accepts int value, how can I determine which GPUs used in the task?
Suppose I have 8 GPUs in the server.

[jameslamb]

In the official doc, it says multiple GPUs is supported in CUDA version

Please share a link to what you're referring to with this statement.

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@shiyu1994 could you answer the other parts of this report?

[HenrySun98]

@jameslamb

https://lightgbm.readthedocs.io/en/latest/Parameters.html#num_gpu

I found this link for num_gpu parameter.

[HenrySun98]

@jameslamb @shiyu1994 expect your replies, many thx

[bstockton]

@jameslamb Is there any update on this? This seems like a very direct conflict with the documentation and implemented code that is causing a lot of confusion.

[eadeoye-Arcadia]

Same please address this potential conflict in documentation.