PyTorch에서 8비트 옵티마이저를 사용하는 방법

RuntimeError: CUDA out of memory. Tried to allocate .. MiB (.. GiB total capacity; ... GiB already allocated; 
... MiB free; ... GiB reserved in total by PyTorch)

import bitsandbytes as bnb

model = ...
optimizer = bnb.optim.Adam8bit(model.parameters(), lr=0.001) # instead of torch.optim.Adam

for epoch in range(...):
    for i, sample in enumerate(dataloader):
        inputs, labels = sample
        optimizer.zero_grad()

	# Forward Pass
        outputs = model(inputs)
        # Compute Loss and Perform Back-propagation
	loss = loss_fn(outputs, labels)
        loss.backward()
	# Update Optimizer
        optimizer.step()