Thread through the scaling type argument to float8 constructors

ghstack-source-id: 6f9b9299f4429ede127c0ed639a652d8888e947a
Pull Request resolved: #301

.pre-commit-config.yaml

@@ -10,8 +10,6 @@ repos:
     -   id: trailing-whitespace
     -   id: check-ast
     -   id: check-merge-conflict
-    -   id: no-commit-to-branch
-        args: ['--branch=main']
     -   id: check-added-large-files
         args: ['--maxkb=500']
     -   id: end-of-file-fixer

float8_experimental/float8_dynamic_linear.py

@@ -19,6 +19,7 @@
     Float8Tensor,
     merge_mm_configs,
     ScaledMMConfig,
+    ScalingGranularity,
     tensor_already_casted_to_fp8,
     to_fp8_no_autograd,
 )
@@ -36,21 +37,26 @@ class NoopFwToFloat8E5M2Bw(torch.autograd.Function):
     @staticmethod
     def forward(
         ctx,
-        tensor,
+        tensor: torch.Tensor,
         mm_config: ScaledMMConfig,
+        scaling_granularity: ScalingGranularity,
     ):
         ctx.mm_config = mm_config
+        ctx.scaling_granularity = scaling_granularity
         return tensor
 
     @staticmethod
-    def backward(ctx, gradY):
+    def backward(ctx, gradY: torch.Tensor):
         if tensor_already_casted_to_fp8(gradY):
-            return gradY, None
-        gradY_scale = tensor_to_scale(gradY, e5m2_dtype)
+            return gradY, None, None
+        gradY_scale = tensor_to_scale(gradY, e5m2_dtype, ctx.scaling_granularity)
         fp8_tensor = to_fp8_no_autograd(
-            gradY, gradY_scale, e5m2_dtype, mm_config=ctx.mm_config
+            gradY,
+            gradY_scale,
+            e5m2_dtype,
+            mm_config=ctx.mm_config,
         )
-        return fp8_tensor, None
+        return fp8_tensor, None, None
 
 
 class Float8DynamicLinear(torch.nn.Linear):
@@ -63,13 +69,19 @@ def __init__(self, **super_kwargs):
         super().__init__(**super_kwargs)
 
     def forward(self, input: torch.Tensor) -> torch.Tensor:
-        x_fp8 = cast_to_float8_e4m3_dynamic(input, self.forward_config)
+        x_fp8 = cast_to_float8_e4m3_dynamic(
+            input, self.forward_config, self.scaling_granularity
+        )
         if isinstance(self.weight, Float8Tensor):  # cast by FSDP
             w_fp8 = self.weight
         else:
-            w_fp8 = cast_to_float8_e4m3_dynamic(self.weight, self.forward_config)
+            w_fp8 = cast_to_float8_e4m3_dynamic(
+                self.weight, self.forward_config, self.scaling_granularity
+            )
         y = torch.nn.functional.linear(x_fp8, w_fp8, self.bias)
-        y = cast_to_float8_e5m2_dynamic_bw(y, self.backward_config)
+        y = cast_to_float8_e5m2_dynamic_bw(
+            y, self.backward_config, self.scaling_granularity
+        )
         return y
 
     @classmethod
@@ -101,9 +113,14 @@ def from_float(cls, mod, emulate: bool = False) -> "Float8DynamicLinear":
             fp8_output=False,
             pad_inner_dim=config.pad_inner_dim,
         )
+        # TODO: For now hardcode TensorWise scaling
+        new_mod.scaling_granularity = ScalingGranularity.TensorWise
+
         if config.enable_fsdp_fp8_all_gather:
             new_mod.weight = nn.Parameter(
-                WeightWithDynamicFloat8CastTensor(mod.weight, new_mod.forward_config)
+                WeightWithDynamicFloat8CastTensor(
+                    mod.weight, new_mod.forward_config, new_mod.scaling_granularity
+                )
             )
         else:
             new_mod.weight = mod.weight
@@ -112,18 +129,31 @@ def from_float(cls, mod, emulate: bool = False) -> "Float8DynamicLinear":
 
 
 def cast_to_float8_e4m3_dynamic(
-    inpt_tensor: torch.Tensor, mm_config: ScaledMMConfig, reduce_amax: bool = False
+    inpt_tensor: torch.Tensor,
+    mm_config: ScaledMMConfig,
+    scaling_granularity: ScalingGranularity,
+    reduce_amax: bool = False,
 ) -> Float8Tensor:
     if tensor_already_casted_to_fp8(inpt_tensor):
         return inpt_tensor
-    scale = tensor_to_scale(inpt_tensor, e4m3_dtype, reduce_amax)
-    return Float8Tensor.to_float8(inpt_tensor, scale, e4m3_dtype, mm_config=mm_config)
+    scale = tensor_to_scale(
+        inpt_tensor, e4m3_dtype, scaling_granularity, reduce_amax=reduce_amax
+    )
+    return Float8Tensor.to_float8(
+        inpt_tensor,
+        scale,
+        e4m3_dtype,
+        mm_config=mm_config,
+        scaling_granularity=scaling_granularity,
+    )
 
 
 def cast_to_float8_e5m2_dynamic_bw(
-    gradY: torch.Tensor, mm_config: ScaledMMConfig
+    gradY: torch.Tensor,
+    mm_config: ScaledMMConfig,
+    scaling_granularity: ScalingGranularity,
 ) -> torch.Tensor:
-    return NoopFwToFloat8E5M2Bw.apply(gradY, mm_config)
+    return NoopFwToFloat8E5M2Bw.apply(gradY, mm_config, scaling_granularity)
 
 
 # FSDP pads its local tensor on dim-0. The subclass should be preserved such
@@ -143,7 +173,12 @@ def cast_to_float8_e5m2_dynamic_bw(
 
 class WeightWithDynamicFloat8CastTensor(torch.Tensor):
     @staticmethod
-    def __new__(cls, tensor: torch.Tensor, mm_config: ScaledMMConfig):
+    def __new__(
+        cls,
+        tensor: torch.Tensor,
+        mm_config: ScaledMMConfig,
+        scaling_granularity: ScalingGranularity,
+    ):
         return torch.Tensor._make_wrapper_subclass(
             cls,
             tensor.size(),
@@ -157,24 +192,38 @@ def __new__(cls, tensor: torch.Tensor, mm_config: ScaledMMConfig):
             requires_grad=tensor.requires_grad,
         )
 
-    def __init__(self, tensor: torch.Tensor, mm_config: ScaledMMConfig):
+    def __init__(
+        self,
+        tensor: torch.Tensor,
+        mm_config: ScaledMMConfig,
+        scaling_granularity: ScalingGranularity,
+    ):
         self._tensor = tensor
         self._mm_config = mm_config
+        self._scaling_granularity = scaling_granularity
 
     @classmethod
     def __torch_dispatch__(cls, func, types, args, kwargs=None):
         if func == torch.ops.aten.detach.default:
             return WeightWithDynamicFloat8CastTensor(
-                args[0]._tensor, args[0]._mm_config
+                args[0]._tensor, args[0]._mm_config, args[0]._scaling_granularity
             )
         mm_config: Optional[ScaledMMConfig] = None
+        scaling_granularity: Optional[ScalingGranularity] = None
 
         def unwrap(t):
             nonlocal mm_config
+            nonlocal scaling_granularity
             if mm_config is None:
                 mm_config = t._mm_config
             else:
                 mm_config = merge_mm_configs(mm_config, t._mm_config)
+
+            if scaling_granularity is None:
+                scaling_granularity = t._scaling_granularity
+            else:
+                # TODO For now we assume that the scaling granularity is same across all tensors
+                assert scaling_granularity == t._scaling_granularity
             return t._tensor
 
         args, kwargs = pytree.tree_map_only(
@@ -184,23 +233,33 @@ def unwrap(t):
         if func not in _ops_to_preserve_subclass:
             return out
         return pytree.tree_map_only(
-            torch.Tensor, lambda x: WeightWithDynamicFloat8CastTensor(x, mm_config), out
+            torch.Tensor,
+            lambda x: WeightWithDynamicFloat8CastTensor(
+                x, mm_config, scaling_granularity
+            ),
+            out,
         )
 
     def __tensor_flatten__(self):
-        return ["_tensor"], self._mm_config
+        return ["_tensor"], {
+            "_mm_config": self._mm_config,
+            "_scaling_granularity": self._scaling_granularity,
+        }
 
     @staticmethod
     def __tensor_unflatten__(inner_tensors, flatten_spec, outer_size, outer_stride):
-        mm_config = flatten_spec
-        return WeightWithDynamicFloat8CastTensor(inner_tensors["_tensor"], mm_config)
+        mm_config = flatten_spec["_mm_config"]
+        scaling_granularity = flatten_spec["_scaling_granularity"]
+        return WeightWithDynamicFloat8CastTensor(
+            inner_tensors["_tensor"], mm_config, scaling_granularity
+        )
 
     def __repr__(self):
-        return f"WeightWithDynamicFloat8CastTensor(tensor={self._tensor}, mm_config={self._mm_config})"
+        return f"WeightWithDynamicFloat8CastTensor(tensor={self._tensor}, mm_config={self._mm_config}, scaling_granularity={self._scaling_granularity})"
 
     def fsdp_pre_all_gather(self, mesh):
         float8_tensor = cast_to_float8_e4m3_dynamic(
-            self._tensor, self._mm_config, reduce_amax=True
+            self._tensor, self._mm_config, self._scaling_granularity, reduce_amax=True
         )
         return (float8_tensor._data,), (float8_tensor._scale,)
 

float8_experimental/float8_linear.py

@@ -25,6 +25,7 @@
 from float8_experimental.float8_tensor import (
     Float8Tensor,
     ScaledMMConfig,
+    ScalingGranularity,
     to_fp8_no_autograd,
 )
 
@@ -45,6 +46,7 @@ def _maybe_initialize_amaxes_scales_for_float8_cast(
     float8_dtype,
     is_initialized,
     reduce_amax,
+    scaling_granularity: ScalingGranularity,
 ):
     """
     If x is about to be cast to `float8` and the amax buffers are not initialized,
@@ -56,7 +58,7 @@ def _maybe_initialize_amaxes_scales_for_float8_cast(
         # Note: we need to enable distributed reduction here in order
         # to match numerics between single GPU and multi GPU code for
         # activations and gradients
-        new_amax = tensor_to_amax(x, reduce_amax=reduce_amax)
+        new_amax = tensor_to_amax(x, scaling_granularity, reduce_amax=reduce_amax)
         cur_amax.fill_(new_amax)
         amax_history[0] = new_amax
         new_scale = amax_history_to_scale(
@@ -82,11 +84,13 @@ def forward(
         scale_fn_name,
         is_amax_initialized,
         mm_config: ScaledMMConfig,
+        scaling_granularity: ScalingGranularity,
     ):
         ctx.save_for_backward(fp8_amax_dL_dY, fp8_amax_history_dL_dY, fp8_scale_dL_dY)
         ctx.scale_fn_name = scale_fn_name
         ctx.is_amax_initialized = is_amax_initialized
         ctx.mm_config = mm_config
+        ctx.scaling_granularity = scaling_granularity
         return tensor
 
     @staticmethod
@@ -104,14 +108,18 @@ def backward(ctx, go):
             e5m2_dtype,
             is_amax_initialized,
             reduce_amax=True,
+            scaling_granularity=ctx.scaling_granularity,
         )
 
-        fp8_amax_dL_dY.fill_(tensor_to_amax(go))
+        fp8_amax_dL_dY.fill_(tensor_to_amax(go, ctx.scaling_granularity))
 
         res = to_fp8_no_autograd(
-            go, fp8_scale_dL_dY, e5m2_dtype, mm_config=ctx.mm_config
+            go,
+            fp8_scale_dL_dY,
+            e5m2_dtype,
+            mm_config=ctx.mm_config,
         )
-        empty_grads = None, None, None, None, None, None
+        empty_grads = None, None, None, None, None, None, None
         return res, *empty_grads
 
 
@@ -196,6 +204,10 @@ def __init__(self, *args, **kwargs):
             emulate, False, False, config.pad_inner_dim
         )
 
+        # Defines the scaling granularity for the forward and backwards pass
+        # TODO: For now hardcode TensorWise scaling
+        self.scaling_granularity = ScalingGranularity.TensorWise
+
         # Note: is_amax_initialized is not a buffer to avoid data dependent
         # control flow visible to dynamo
         # TODO(future PR): add serialization for this flag
@@ -298,6 +310,7 @@ def cast_x_to_float8(
                 e4m3_dtype,
                 is_amax_initialized,
                 reduce_amax=True,
+                scaling_granularity=self.scaling_granularity,
             )
             x_fp8 = Float8Tensor.to_float8(
                 x,
@@ -308,7 +321,9 @@ def cast_x_to_float8(
             )
         else:
             assert self.scaling_type_x is TensorScalingType.DYNAMIC
-            x_fp8 = cast_to_float8_e4m3_dynamic(x, self.forward_config)
+            x_fp8 = cast_to_float8_e4m3_dynamic(
+                x, self.forward_config, self.scaling_granularity
+            )
         return x_fp8
 
     def cast_w_to_float8(
@@ -325,6 +340,7 @@ def cast_w_to_float8(
                 e4m3_dtype,
                 is_amax_initialized,
                 reduce_amax=False,
+                scaling_granularity=self.scaling_granularity,
             )
 
             w_fp8 = Float8Tensor.to_float8(
@@ -340,7 +356,9 @@ def cast_w_to_float8(
             if isinstance(self.weight, Float8Tensor):  # cast by FSDP
                 w_fp8 = self.weight
             else:
-                w_fp8 = cast_to_float8_e4m3_dynamic(self.weight, self.forward_config)
+                w_fp8 = cast_to_float8_e4m3_dynamic(
+                    self.weight, self.forward_config, self.scaling_granularity
+                )
         return w_fp8
 
     def cast_y_to_float8_in_bw(self, y: torch.Tensor) -> torch.Tensor:
@@ -354,10 +372,13 @@ def cast_y_to_float8_in_bw(self, y: torch.Tensor) -> torch.Tensor:
                 scale_fn_name,
                 self.is_amax_initialized,
                 self.backward_config,
+                self.scaling_granularity,
             )
         else:
             assert self.scaling_type_dL_dY is TensorScalingType.DYNAMIC
-            y = cast_to_float8_e5m2_dynamic_bw(y, self.backward_config)
+            y = cast_to_float8_e5m2_dynamic_bw(
+                y, self.backward_config, self.scaling_granularity
+            )
         return y
 
     def float8_pre_forward(self, x):
@@ -440,7 +461,9 @@ def from_float(
             and config.enable_fsdp_fp8_all_gather
         ):
             new_mod.weight = torch.nn.Parameter(
-                WeightWithDynamicFloat8CastTensor(mod.weight, new_mod.forward_config)
+                WeightWithDynamicFloat8CastTensor(
+                    mod.weight, new_mod.forward_config, new_mod.scaling_granularity
+                )
             )
         else:
             assert not config.enable_fsdp_fp8_all_gather, "unsupported"