Added asymmetric integration to linear layers

Author: ProExpertProg

vllm/model_executor/layers/quantization/compressed_tensors/compressed_tensors.py

@@ -129,7 +129,7 @@ def _is_static_tensor_w8a8(self, weight_quant: BaseModel,
             or weight_quant.strategy == QuantizationStrategy.CHANNEL.value)
         is_tensor = (weight_strategy and input_quant.strategy
                      == QuantizationStrategy.TENSOR.value)
-        is_symmetric = weight_quant.symmetric and input_quant.symmetric
+        is_symmetric = weight_quant.symmetric
         is_static = not weight_quant.dynamic and not input_quant.dynamic
 
         return is_8_bits and is_tensor and is_symmetric and is_static
@@ -142,7 +142,7 @@ def _is_dynamic_token_w8a8(self, weight_quant: BaseModel,
             or weight_quant.strategy == QuantizationStrategy.CHANNEL.value)
         is_token = (weight_strategy and input_quant.strategy
                     == QuantizationStrategy.TOKEN.value)
-        is_symmetric = weight_quant.symmetric and input_quant.symmetric
+        is_symmetric = weight_quant.symmetric
         is_dynamic = not weight_quant.dynamic and input_quant.dynamic
 
         return is_8_bits and is_token and is_symmetric and is_dynamic
@@ -255,12 +255,14 @@ def _get_scheme_from_parts(
             if self._is_static_tensor_w8a8(weight_quant, input_quant):
                 return CompressedTensorsW8A8Int8(
                     strategy=weight_quant.strategy,
-                    is_static_input_scheme=True)
+                    is_static_input_scheme=True,
+                    input_symmetric=input_quant.symmetric)
 
             if self._is_dynamic_token_w8a8(weight_quant, input_quant):
                 return CompressedTensorsW8A8Int8(
                     strategy=weight_quant.strategy,
-                    is_static_input_scheme=False)
+                    is_static_input_scheme=False,
+                    input_symmetric=input_quant.symmetric)
 
         raise NotImplementedError(
             "No compressed-tensors compatible scheme was found.")

vllm/model_executor/layers/quantization/compressed_tensors/schemes/compressed_tensors_w8a8_int8.py

@@ -17,9 +17,11 @@
 
 class CompressedTensorsW8A8Int8(CompressedTensorsScheme):
 
-    def __init__(self, strategy: str, is_static_input_scheme: bool):
+    def __init__(self, strategy: str, is_static_input_scheme: bool,
+                 input_symmetric: bool):
         self.strategy = strategy
         self.is_static_input_scheme = is_static_input_scheme
+        self.input_symmetric = input_symmetric
 
     @classmethod
     def get_min_capability(cls) -> int:
@@ -48,8 +50,21 @@ def process_weights_after_loading(self, layer: torch.nn.Module) -> None:
         if self.is_static_input_scheme:
             layer.input_scale = Parameter(layer.input_scale.max(),
                                           requires_grad=False)
+            if not self.input_symmetric:
+                layer.input_zero_point = Parameter(layer.input_zero_point,
+                                                   requires_grad=False)
+            else:
+                layer.input_zero_point = None
         else:
             layer.input_scale = None
+            layer.input_zero_point = None
+
+        if not self.input_symmetric:
+            layer.azp_adj = layer.weight.sum(dim=0,
+                                             keepdim=True,
+                                             dtype=torch.int32)
+        else:
+            layer.azp_adj = None
 
     def create_weights(self, layer: torch.nn.Module,
                        output_partition_sizes: List[int],
@@ -90,11 +105,18 @@ def create_weights(self, layer: torch.nn.Module,
                                             weight_loader=weight_loader)
             layer.register_parameter("input_scale", input_scale)
 
+            if not self.input_symmetric:
+                raise NotImplementedError(
+                    "static input asymmetric quantization not supported yet")
+                input_zero_point = Parameter(torch.zeros(1, dtype=torch.int8))
+                layer.register_parameter("input_zero_point", input_zero_point)
+
     def apply_weights(self, layer: torch.nn.Module, x: torch.Tensor,
                       bias: Optional[torch.Tensor]) -> torch.Tensor:
-
         return apply_int8_linear(input=x,
                                  weight=layer.weight,
                                  weight_scale=layer.weight_scale,
                                  input_scale=layer.input_scale,
+                                 input_zero_point=layer.input_zero_point,
+                                 azp_adj=layer.azp_adj,
                                  bias=bias)

vllm/model_executor/layers/quantization/utils/w8a8_utils.py

@@ -210,13 +210,28 @@ def apply_int8_linear(
     weight: torch.Tensor,
     weight_scale: torch.Tensor,
     input_scale: Optional[torch.Tensor] = None,
+    input_zero_point: Optional[torch.Tensor] = None,
+    azp_adj: Optional[torch.Tensor] = None,
     bias: Optional[torch.Tensor] = None,
 ):
     # ops.scaled_int8_quant supports both dynamic and static quant.
     # * dynamic, layer.input_scale is None and x_scale computed from x.
     # * static, layer.input_scale is scalar and x_scale is input_scale.
-    x_q, x_scale, _ = ops.scaled_int8_quant(input, input_scale)
-
+    symmetric = azp_adj is None
+    x_q, x_scale, x_zp = ops.scaled_int8_quant(input,
+                                               input_scale,
+                                               input_zero_point,
+                                               symmetric=symmetric)
+
+    if x_zp is not None:
+        return ops.cutlass_scaled_mm_azp(x_q,
+                                         weight,
+                                         scale_a=x_scale,
+                                         scale_b=weight_scale,
+                                         out_dtype=input.dtype,
+                                         azp_adj=azp_adj,
+                                         azp=x_zp,
+                                         bias=bias)
     return ops.cutlass_scaled_mm(x_q,
                                  weight,
                                  scale_a=x_scale,