Workaround a weird quirk of QuantState.to() and add a unit test to exercise it.

This commit is contained in:
Ryan Dick 2024-12-23 22:01:17 +00:00
parent a83a999b79
commit 7214d4969b
2 changed files with 12 additions and 5 deletions

View File

@ -37,5 +37,9 @@ class CustomInvokeLinearNF4(InvokeLinearNF4):
weight = cast_to_device(self.weight, x.device)
self.weight.quant_state = old_quant_state
# For some reason, the quant_state.to(...) implementation fails to cast the quant_state.code field. We do this
# manually here.
weight.quant_state.code = cast_to_device(weight.quant_state.code, x.device)
bias = cast_to_device(self.bias, x.device)
return bnb.matmul_4bit(x, weight.t(), bias=bias, quant_state=weight.quant_state).to(inp_dtype)

View File

@ -81,11 +81,11 @@ def linear_nf4_layer():
torch.manual_seed(1)
orig_layer = torch.nn.Linear(32, 64)
orig_layer = torch.nn.Linear(64, 16)
orig_layer_state_dict = orig_layer.state_dict()
# Prepare a quantized InvokeLinearNF4 layer.
quantized_layer = InvokeLinearNF4(input_features=32, output_features=64)
quantized_layer = InvokeLinearNF4(input_features=64, output_features=16)
quantized_layer.load_state_dict(orig_layer_state_dict)
quantized_layer.to("cuda")
@ -98,7 +98,7 @@ def linear_nf4_layer():
def test_custom_invoke_linear_nf4_all_weights_on_cuda(linear_nf4_layer: InvokeLinearNF4):
"""Test CustomInvokeLinearNF4 inference with all weights on the GPU."""
# Run inference on the original layer.
x = torch.randn(1, 32).to("cuda")
x = torch.randn(1, 64).to("cuda")
y_quantized = linear_nf4_layer(x)
# Wrap the InvokeLinearNF4 layer in a CustomInvokeLinearNF4 layer, and run inference on it.
@ -109,10 +109,13 @@ def test_custom_invoke_linear_nf4_all_weights_on_cuda(linear_nf4_layer: InvokeLi
assert torch.allclose(y_quantized, y_custom, atol=1e-5)
def test_custom_invoke_linear_nf4_all_weights_on_cpu(linear_nf4_layer: InvokeLinearNF4):
# We run with two different input dimensions, because the NF4 layer follows a different code path depending on the
# input dimension, and this has caused issues in the past.
@pytest.mark.parametrize("input_dim_0", [1, 2])
def test_custom_invoke_linear_nf4_all_weights_on_cpu(linear_nf4_layer: InvokeLinearNF4, input_dim_0: int):
"""Test CustomInvokeLinearNF4 inference with all weights on the CPU (streaming to the GPU)."""
# Run inference on the original layer.
x = torch.randn(1, 32).to(device="cuda")
x = torch.randn(input_dim_0, 64).to(device="cuda")
y_quantized = linear_nf4_layer(x)
# Copy the state dict to the CPU and reload it.