[fp8] add fallback and make compile option configurable (#6092)

Author: ver217

colossalai/quantization/fp8.py

@@ -8,6 +8,8 @@
 from packaging.version import Version
 from torch.distributed import ReduceOp
 
+from .fp8_config import dynamic_kernel
+
 SUPPORT_TORCH_COMPILE = Version(torch.__version__) >= Version("2.4.0")
 SCALE_BYTES = 4
 try:
@@ -832,11 +834,13 @@ def backward(ctx: Any, out_grad) -> Any:
         return x_grad.reshape(ctx.x_shape), w_grad, bias_grad
 
 
-@torch.compile(mode="max-autotune-no-cudagraphs", disable=not SUPPORT_TORCH_COMPILE, dynamic=False)
+@torch.compile(mode="max-autotune-no-cudagraphs", disable=not SUPPORT_TORCH_COMPILE, dynamic=dynamic_kernel)
 def _linear_fp8(input: torch.Tensor, weight: torch.Tensor, bias: Optional[torch.Tensor] = None) -> torch.Tensor:
     return _LinearFp8.apply(input, weight, bias)
 
 
 def linear_fp8(input: torch.Tensor, weight: torch.Tensor, bias: Optional[torch.Tensor] = None) -> torch.Tensor:
+    if input.shape[-1] % 16 != 0 or np.prod(input.shape[:-1]) % 16 != 0:
+        return F.linear(input, weight, bias)
     out = _linear_fp8(input, weight, bias)
     return out

colossalai/quantization/fp8_config.py

@@ -0,0 +1 @@
+dynamic_kernel: bool = False