[Kernel] AQ AZP 4/4: Integrate asymmetric quantization to linear method (vllm-project#7271)

Signed-off-by: Alvant <[email protected]>

Author: ProExpertProg

.buildkite/lm-eval-harness/configs/Meta-Llama-3-8B-Instruct-INT8-compressed-tensors-asym.yaml

@@ -0,0 +1,11 @@
+# bash .buildkite/lm-eval-harness/run-lm-eval-gsm-vllm-baseline.sh -m nm-testing/Meta-Llama-3-8B-Instruct-W8-Channel-A8-Dynamic-Asym-Per-Token-Test -b "auto" -l 250 -f 5 -t 1
+model_name: "nm-testing/Meta-Llama-3-8B-Instruct-W8-Channel-A8-Dynamic-Asym-Per-Token-Test"
+tasks:
+- name: "gsm8k"
+  metrics:
+  - name: "exact_match,strict-match"
+    value: 0.764
+  - name: "exact_match,flexible-extract"
+    value: 0.764
+limit: 250
+num_fewshot: 5

.buildkite/lm-eval-harness/configs/models-small.txt

@@ -1,6 +1,7 @@
 Meta-Llama-3-8B-Instruct.yaml
 Meta-Llama-3-8B-Instruct-FP8-compressed-tensors.yaml
 Meta-Llama-3-8B-Instruct-INT8-compressed-tensors.yaml
+Meta-Llama-3-8B-Instruct-INT8-compressed-tensors-asym.yaml
 Meta-Llama-3-8B-Instruct-nonuniform-compressed-tensors.yaml
 Meta-Llama-3-8B-Instruct-Channelwise-compressed-tensors.yaml
 Minitron-4B-Base-FP8.yaml

.buildkite/lm-eval-harness/test_lm_eval_correctness.py

@@ -49,10 +49,15 @@ def test_lm_eval_correctness():
     results = launch_lm_eval(eval_config)
 
     # Confirm scores match ground truth.
+    success = True
     for task in eval_config["tasks"]:
         for metric in task["metrics"]:
             ground_truth = metric["value"]
             measured_value = results["results"][task["name"]][metric["name"]]
             print(f'{task["name"]} | {metric["name"]}: '
                   f'ground_truth={ground_truth} | measured={measured_value}')
-            assert numpy.isclose(ground_truth, measured_value, rtol=RTOL)
+            success = success and numpy.isclose(
+                ground_truth, measured_value, rtol=RTOL)
+
+    # Assert at the end, print all scores even on failure for debugging.
+    assert success

tests/quantization/test_compressed_tensors.py

@@ -2,6 +2,7 @@
 
 Run `pytest tests/quantization/test_compressed_tensors.py`.
 """
+from typing import Optional
 
 import pytest
 import torch
@@ -14,14 +15,16 @@
     QuantizationType)
 
 
-@pytest.mark.parametrize("model_args", [
-    ("nm-testing/tinyllama-oneshot-w8w8-test-static-shape-change", "tensor",
-     QuantizationType.INT, 2560),
-    ("nm-testing/tinyllama-oneshot-w8-channel-a8-tensor", "channel",
-     QuantizationType.INT, 2560),
-])
+@pytest.mark.parametrize(
+    "model_args",
+    [("nm-testing/tinyllama-oneshot-w8w8-test-static-shape-change", "tensor",
+      QuantizationType.INT, 2560, True),
+     ("nm-testing/tinyllama-oneshot-w8-channel-a8-tensor", "channel",
+      QuantizationType.INT, 2560, True),
+     ("nm-testing/asym-w8w8-int8-static-per-tensor-tiny-llama", "tensor",
+      QuantizationType.INT, 2560, False)])
 def test_compressed_tensors_w8a8_static_setup(vllm_runner, model_args):
-    model_path, strategy, quant_type, shape_0 = model_args
+    model_path, strategy, quant_type, shape_0, is_symmetric = model_args
     with vllm_runner(model_path, enforce_eager=True) as llm:
         model = llm.model.llm_engine.model_executor.driver_worker.model_runner.model  # noqa: E501
         layer = model.model.layers[0]
@@ -31,6 +34,18 @@ def test_compressed_tensors_w8a8_static_setup(vllm_runner, model_args):
         gate_up_proj = layer.mlp.gate_up_proj
         down_proj = layer.mlp.down_proj
 
+        # assert zp for symmetric and asymmetric cases
+        def zp_valid(zp: Optional[torch.Tensor]):
+            if is_symmetric:
+                return zp is None
+
+            return zp is not None and zp.dtype is torch.int32
+
+        assert zp_valid(qkv_proj.input_zero_point)
+        assert zp_valid(o_proj.input_zero_point)
+        assert zp_valid(gate_up_proj.input_zero_point)
+        assert zp_valid(down_proj.input_zero_point)
+
         assert isinstance(qkv_proj.quant_method, CompressedTensorsLinearMethod)
         assert isinstance(o_proj.quant_method, CompressedTensorsLinearMethod)
         assert isinstance(gate_up_proj.quant_method,
@@ -69,9 +84,12 @@ def test_compressed_tensors_no_enforce_eager(vllm_runner):
 
 @pytest.mark.parametrize("model_args", [
     ("nm-testing/tinyllama-oneshot-w8a8-dynamic-token-v2", "tensor"),
+    ("nm-testing/tinyllama-oneshot-w8a8-dynamic-token-v2-asym", "tensor"),
     ("nm-testing/tinyllama-oneshot-w8a8-channel-dynamic-token-v2", "channel"),
+    ("nm-testing/tinyllama-oneshot-w8a8-channel-dynamic-token-v2-asym",
+     "channel"),
 ])
-def test_compressed_tensors_w8a8_dynanmic_per_token(vllm_runner, model_args):
+def test_compressed_tensors_w8a8_dynamic_per_token(vllm_runner, model_args):
     model_path, strategy = model_args
     with vllm_runner(model_path, dtype=torch.float16) as llm:
         model = llm.model.llm_engine.model_executor.driver_worker.model_runner.model  # noqa: E501
@@ -160,4 +178,4 @@ def test_compressed_tensors_kv_cache(vllm_runner):
     model_path = "nm-testing/TinyLlama-1.1B-compressed-tensors-kv-cache-scheme"
     with vllm_runner(model_path, kv_cache_dtype="fp8") as llm:
         output = llm.generate_greedy("Hello world!", max_tokens=20)
-        assert output
+        assert output

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

@@ -138,10 +138,11 @@ 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_static = not weight_quant.dynamic and not input_quant.dynamic
 
-        return is_8_bits and is_tensor and is_symmetric and is_static
+        # Both symmetric and asymmetric input quantization supported.
+        # Only symmetric weight quantization supported.
+        return is_8_bits and is_tensor and weight_quant.symmetric and is_static
 
     def _is_dynamic_token_w8a8(self, weight_quant: BaseModel,
                                input_quant: BaseModel) -> bool:
@@ -151,10 +152,11 @@ 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_dynamic = not weight_quant.dynamic and input_quant.dynamic
 
-        return is_8_bits and is_token and is_symmetric and is_dynamic
+        # Both symmetric and asymmetric input quantization supported.
+        # Only symmetric weight quantization supported.
+        return is_8_bits and is_token and weight_quant.symmetric and is_dynamic
 
     def _is_fp8_w8a8(self, weight_quant: BaseModel,
                      input_quant: BaseModel) -> bool:
@@ -265,12 +267,14 @@ 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

@@ -3,6 +3,7 @@
 import torch
 from torch.nn import Parameter
 
+from vllm.logger import init_logger
 from vllm.model_executor.layers.quantization.compressed_tensors.schemes import (
     CompressedTensorsScheme)
 from vllm.model_executor.layers.quantization.compressed_tensors.utils import (
@@ -14,12 +15,16 @@
                                            ModelWeightParameter,
                                            PerTensorScaleParameter)
 
+logger = init_logger(__name__)
+
 
 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:
@@ -46,10 +51,43 @@ def process_weights_after_loading(self, layer: torch.nn.Module) -> None:
                                            requires_grad=False)
         # INPUT SCALE
         if self.is_static_input_scheme:
-            layer.input_scale = Parameter(layer.input_scale.max(),
-                                          requires_grad=False)
+            if self.input_symmetric:
+                layer.input_scale = Parameter(layer.input_scale.max(),
+                                              requires_grad=False)
+                layer.input_zero_point = None
+            else:
+                # reconstruct the ranges
+                int8_traits = torch.iinfo(torch.int8)
+                azps = layer.input_zero_point.to(dtype=torch.int32)
+                range_max = (layer.input_scale *
+                             (int8_traits.max - azps)).max()
+                range_min = (layer.input_scale *
+                             (int8_traits.min - azps)).min()
+
+                scale = (range_max - range_min) / (int8_traits.max -
+                                                   int8_traits.min)
+                layer.input_scale = Parameter(scale, requires_grad=False)
+
+                # AZP loaded as int8 but used as int32
+                azp = (int8_traits.min -
+                       range_min / scale).to(dtype=torch.int32)
+                layer.input_zero_point = Parameter(azp, requires_grad=False)
+
         else:
             layer.input_scale = None
+            layer.input_zero_point = None
+
+        # azp_adj is the AZP adjustment term, used to account for weights.
+        # It does not depend on scales or azp, so it is the same for
+        # static and dynamic quantization.
+        # For more details, see csrc/quantization/cutlass_w8a8/Epilogues.md
+        # https://github.com/vllm-project/vllm/blob/8d59dbb00044a588cab96bcdc028006ed922eb06/csrc/quantization/cutlass_w8a8/Epilogues.md
+        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 +128,22 @@ def create_weights(self, layer: torch.nn.Module,
                                             weight_loader=weight_loader)
             layer.register_parameter("input_scale", input_scale)
 
+            if not self.input_symmetric:
+                # Note: compressed-tensors stores the zp using the same dtype
+                # as the weights
+                # AZP loaded as int8 but used as int32
+                input_zero_point = BasevLLMParameter(
+                    data=torch.empty(1, dtype=torch.int8),
+                    weight_loader=weight_loader)
+                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

@@ -191,13 +191,28 @@ 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,