How to use all the available GPUs

[mnslarcher]

Hi all, I migrated my code to the latest version of lightnining and tried using accelerator=auto and devices=-1 to use all available GPUs but I get:

UserWarning: The flag devices=-1 will be ignored, instead the device specific number 1

What is the recommended way to use, by default, all GPUs (when present)?

[akihironitta]

Hi @mnslarcher! To use all of available devices, use:

Trainer(..., devices="auto")

The doc page is available here: https://pytorch-lightning.readthedocs.io/en/latest/common/trainer.html#devices

[mnslarcher]

Thanks @akihironitta , this is what I did, I was thinking that the the "-1" was wrong but then I check again the doc and found that what I did was exactly what the doc (and you) suggest, I then opened this issue: #12756

[akihironitta]

For anyone seeing this discussion, have a look at #12756 (comment).