[FP8]add FP8 WoQ kernel abstraction. (#32929)

Signed-off-by: Zhu, Zufang <zufang.zhu@intel.com>

vllm/model_executor/kernels/linear/__init__.py

@@ -72,6 +72,9 @@ from vllm.model_executor.kernels.linear.scaled_mm.cutlass import (
 from vllm.model_executor.kernels.linear.scaled_mm.flashinfer import (
     FlashInferFP8ScaledMMLinearKernel,
 )
+from vllm.model_executor.kernels.linear.scaled_mm.marlin import (
+    MarlinFP8ScaledMMLinearKernel,
+)
 from vllm.model_executor.kernels.linear.scaled_mm.pytorch import (
     ChannelWiseTorchFP8ScaledMMLinearKernel,
     PerTensorTorchFP8ScaledMMLinearKernel,
@@ -104,6 +107,7 @@ _POSSIBLE_INT8_KERNELS: dict[PlatformEnum, list[type[Int8ScaledMMLinearKernel]]]
 # in priority/performance order (when available)
 _POSSIBLE_FP8_KERNELS: dict[PlatformEnum, list[type[FP8ScaledMMLinearKernel]]] = {
     PlatformEnum.CUDA: [
+        MarlinFP8ScaledMMLinearKernel,
         FlashInferFP8ScaledMMLinearKernel,
         CutlassFP8ScaledMMLinearKernel,
         PerTensorTorchFP8ScaledMMLinearKernel,

vllm/model_executor/kernels/linear/scaled_mm/__init__.py

@@ -14,6 +14,9 @@ from vllm.model_executor.kernels.linear.scaled_mm.cutlass import (
 from vllm.model_executor.kernels.linear.scaled_mm.flashinfer import (
     FlashInferFP8ScaledMMLinearKernel,
 )
+from vllm.model_executor.kernels.linear.scaled_mm.marlin import (
+    MarlinFP8ScaledMMLinearKernel,
+)
 from vllm.model_executor.kernels.linear.scaled_mm.pytorch import (
     ChannelWiseTorchFP8ScaledMMLinearKernel,
     PerTensorTorchFP8ScaledMMLinearKernel,
@@ -46,6 +49,7 @@ __all__ = [
     "CutlassFP8ScaledMMLinearKernel",
     "CutlassInt8ScaledMMLinearKernel",
     "FlashInferFP8ScaledMMLinearKernel",
+    "MarlinFP8ScaledMMLinearKernel",
     "ChannelWiseTorchFP8ScaledMMLinearKernel",
     "PerTensorTorchFP8ScaledMMLinearKernel",
     "RowWiseTorchFP8ScaledMMLinearKernel",

vllm/model_executor/kernels/linear/scaled_mm/marlin.py

+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: Copyright contributors to the vLLM project
+
+from collections.abc import Sequence
+
+import torch
+
+import vllm.envs as envs
+from vllm.model_executor.layers.batch_invariant import vllm_is_batch_invariant
+from vllm.model_executor.layers.quantization.utils.fp8_utils import (
+    process_fp8_weight_block_strategy,
+)
+from vllm.model_executor.layers.quantization.utils.marlin_utils_fp8 import (
+    apply_fp8_marlin_linear,
+    is_fp8_marlin_supported,
+    prepare_fp8_layer_for_marlin,
+)
+from vllm.model_executor.layers.quantization.utils.quant_utils import (
+    kFp8Static128BlockSym,
+)
+from vllm.model_executor.utils import replace_parameter
+from vllm.platforms import current_platform
+
+from .ScaledMMLinearKernel import (
+    FP8ScaledMMLinearKernel,
+    FP8ScaledMMLinearLayerConfig,
+)
+
+
+class MarlinFP8ScaledMMLinearKernel(FP8ScaledMMLinearKernel):
+    """
+    FP8 Marlin kernel for GPUs that lack FP8 hardware support.
+    Leverages the Marlin kernel for fast weight-only FP8 quantization.
+    """
+
+    @classmethod
+    def is_supported(
+        cls, compute_capability: int | None = None
+    ) -> tuple[bool, str | None]:
+        if not current_platform.is_cuda():
+            return False, "requires CUDA."
+        # Check if platform supports FP8 Marlin
+        if not is_fp8_marlin_supported():
+            return False, "FP8 Marlin requires compute capability 7.5 or higher"
+        if vllm_is_batch_invariant():
+            return False, "FP8 Marlin not supported for batch invariant execution."
+        if (
+            compute_capability is not None
+            and compute_capability >= 89
+            and not envs.VLLM_TEST_FORCE_FP8_MARLIN
+        ):
+            return (
+                False,
+                "To apply FP8 Marlin on high-capability GPUs, please set "
+                "VLLM_TEST_FORCE_FP8_MARLIN=1",
+            )
+        return True, None
+
+    @classmethod
+    def can_implement(cls, c: FP8ScaledMMLinearLayerConfig) -> tuple[bool, str | None]:
+        return True, None
+
+    def __init__(
+        self, c: FP8ScaledMMLinearLayerConfig, layer_param_names: Sequence[str]
+    ) -> None:
+        super().__init__(c, layer_param_names)
+        self.marlin_input_dtype = None
+        self.block_quant = self.config.weight_quant_key in {kFp8Static128BlockSym}
+        self.size_k_first = not self.block_quant
+
+    def process_weights_after_loading(self, layer: torch.nn.Module) -> None:
+        if self.block_quant:
+            weight, weight_scale_inv = process_fp8_weight_block_strategy(
+                layer.weight, layer.weight_scale_inv
+            )
+            # Update layer with new values
+            replace_parameter(layer, "weight", weight.data)
+            replace_parameter(layer, "weight_scale_inv", weight_scale_inv.data)
+        else:
+            weight = layer.weight.t()
+            replace_parameter(layer, "weight", weight.data)
+        layer.input_scale = None
+        prepare_fp8_layer_for_marlin(
+            layer, self.size_k_first, input_dtype=self.marlin_input_dtype
+        )
+        del layer.input_scale
+
+    def apply_weights(
+        self,
+        layer: torch.nn.Module,
+        x: torch.Tensor,
+        bias: torch.Tensor | None = None,
+    ) -> torch.Tensor:
+        if self.block_quant:
+            weight_scale = layer.weight_scale_inv
+        else:
+            weight_scale = layer.weight_scale
+        return apply_fp8_marlin_linear(
+            input=x,
+            weight=layer.weight,
+            weight_scale=weight_scale,
+            workspace=layer.workspace,
+            size_n=layer.output_size_per_partition,
+            size_k=layer.input_size_per_partition,
+            input_dtype=self.marlin_input_dtype,
+            bias=bias,
+        )
+
+    def apply_scaled_mm(
+        self,
+        *,
+        A: torch.Tensor,
+        B: torch.Tensor,
+        out_dtype: torch.dtype,
+        As: torch.Tensor,
+        Bs: torch.Tensor,
+        bias: torch.Tensor | None,
+        output_shape: list,
+    ) -> torch.Tensor:
+        pass

vllm/model_executor/layers/quantization/fbgemm_fp8.py

@@ -22,7 +22,6 @@ from vllm.model_executor.layers.quantization.base_config import (
     QuantizeMethodBase,
 )
 from vllm.model_executor.layers.quantization.utils.marlin_utils_fp8 import (
-    apply_fp8_marlin_linear,
     prepare_fp8_layer_for_marlin,
 )
 from vllm.model_executor.layers.quantization.utils.quant_utils import (
@@ -177,15 +176,4 @@ class FBGEMMFp8LinearMethod(LinearMethodBase):
         x: torch.Tensor,
         bias: torch.Tensor | None = None,
     ) -> torch.Tensor:
-        if self.quant_config.use_marlin:
-            return apply_fp8_marlin_linear(
-                input=x,
-                weight=layer.weight,
-                weight_scale=layer.weight_scale,
-                workspace=layer.workspace,
-                size_n=layer.output_size_per_partition,
-                size_k=layer.input_size_per_partition,
-                bias=bias,
-            )
-
         return self.fp8_linear.apply_weights(layer, x, bias)

vllm/model_executor/layers/quantization/fp8.py

@@ -7,7 +7,6 @@ import torch
 from torch.nn import Module
 from torch.utils._python_dispatch import TorchDispatchMode
 
-import vllm.envs as envs
 import vllm.model_executor.layers.fused_moe.modular_kernel as mk
 from vllm import _custom_ops as ops
 from vllm._aiter_ops import rocm_aiter_ops
@@ -16,6 +15,7 @@ from vllm.logger import init_logger
 from vllm.model_executor.kernels.linear import (
     init_fp8_linear_kernel,
 )
+from vllm.model_executor.kernels.linear.scaled_mm import MarlinFP8ScaledMMLinearKernel
 from vllm.model_executor.layers.attention import Attention
 from vllm.model_executor.layers.batch_invariant import (
     vllm_is_batch_invariant,
@@ -61,10 +61,6 @@ from vllm.model_executor.layers.quantization.utils.fp8_utils import (
 from vllm.model_executor.layers.quantization.utils.marlin_utils import (
     get_marlin_input_dtype,
 )
-from vllm.model_executor.layers.quantization.utils.marlin_utils_fp8 import (
-    apply_fp8_marlin_linear,
-    prepare_fp8_layer_for_marlin,
-)
 from vllm.model_executor.layers.quantization.utils.quant_utils import (
     GroupShape,
     is_layer_skipped,
@@ -280,15 +276,6 @@ class Fp8LinearMethod(LinearMethodBase):
         # For GPUs that lack FP8 hardware support, we can leverage the Marlin
         # kernel for fast weight-only FP8 quantization
         self.marlin_input_dtype = None
-        self.use_marlin = (
-            not current_platform.has_device_capability(89)
-            or envs.VLLM_TEST_FORCE_FP8_MARLIN
-        )
-        # Disable marlin for rocm
-        if current_platform.is_rocm() or current_platform.is_xpu():
-            self.use_marlin = False
-        if vllm_is_batch_invariant():
-            self.use_marlin = False
 
         self.use_aiter_and_is_supported = rocm_aiter_ops.is_linear_fp8_enabled()
         self.use_deep_gemm = is_deep_gemm_supported()
@@ -297,16 +284,6 @@ class Fp8LinearMethod(LinearMethodBase):
         self.block_quant = self.weight_block_size is not None
         self.act_q_static = self.quant_config.activation_scheme == "static"
 
-        if self.block_quant:
-            assert not self.act_q_static
-            assert self.weight_block_size is not None
-            self.w8a8_block_fp8_linear = W8A8BlockFp8LinearOp(
-                weight_group_shape=GroupShape(*self.weight_block_size),
-                act_quant_group_shape=GroupShape(1, self.weight_block_size[0]),
-                cutlass_block_fp8_supported=self.cutlass_block_fp8_supported,
-                use_aiter_and_is_supported=self.use_aiter_and_is_supported,
-            )
-        else:
         # Use per-token quantization for better perf if dynamic and cutlass
         if self.act_q_static:
             activation_quant_key = kFp8StaticTensorSym
@@ -315,12 +292,28 @@ class Fp8LinearMethod(LinearMethodBase):
         else:
             activation_quant_key = kFp8DynamicTensorSym
 
+        if self.block_quant:
+            weight_quant_key = kFp8Static128BlockSym
+        else:
+            weight_quant_key = kFp8StaticTensorSym
+
         self.fp8_linear = init_fp8_linear_kernel(
             activation_quant_key=activation_quant_key,
-                weight_quant_key=kFp8StaticTensorSym,
+            weight_quant_key=weight_quant_key,
             out_dtype=torch.get_default_dtype(),
             module_name=self.__class__.__name__,
         )
+        self.use_marlin = isinstance(self.fp8_linear, MarlinFP8ScaledMMLinearKernel)
+
+        if self.block_quant and not self.use_marlin:
+            assert not self.act_q_static
+            assert self.weight_block_size is not None
+            self.w8a8_block_fp8_linear = W8A8BlockFp8LinearOp(
+                weight_group_shape=GroupShape(*self.weight_block_size),
+                act_quant_group_shape=GroupShape(1, self.weight_block_size[0]),
+                cutlass_block_fp8_supported=self.cutlass_block_fp8_supported,
+                use_aiter_and_is_supported=self.use_aiter_and_is_supported,
+            )
 
     def create_weights(
         self,
@@ -387,12 +380,18 @@ class Fp8LinearMethod(LinearMethodBase):
             layer.register_parameter("input_scale", scale)
 
     def process_weights_after_loading(self, layer: Module) -> None:
-        size_k_first = True
+        if self.use_marlin:
+            # Only Marlin kernels support `marlin_input_dtype`; guard to avoid
+            # AttributeError if backend selection changes.
+            if hasattr(self.fp8_linear, "marlin_input_dtype"):
+                self.fp8_linear.marlin_input_dtype = self.marlin_input_dtype
+            self.fp8_linear.process_weights_after_loading(layer)
+            return
+
         input_scale = None
         # TODO(rob): refactor block quant into separate class.
         if self.block_quant:
             assert not self.act_q_static
-            size_k_first = False
 
             weight, weight_scale_inv = process_fp8_weight_block_strategy(
                 layer.weight, layer.weight_scale_inv
@@ -411,7 +410,6 @@ class Fp8LinearMethod(LinearMethodBase):
 
             # If using w8a8, torch._scaled_mm needs per tensor, so
             # requantize the logical shards as a single weight.
-            if not self.use_marlin:
             weight, weight_scale, input_scale = process_fp8_weight_tensor_strategy(
                 weight,
                 weight_scale,
@@ -432,14 +430,6 @@ class Fp8LinearMethod(LinearMethodBase):
         else:
             layer.input_scale = None
 
-        if self.use_marlin:
-            prepare_fp8_layer_for_marlin(
-                layer, size_k_first, input_dtype=self.marlin_input_dtype
-            )
-            # Activations not quantized for marlin.
-            del layer.input_scale
-            return
-
         if self.block_quant:
             maybe_post_process_fp8_weight_block(layer)
 
@@ -486,21 +476,7 @@ class Fp8LinearMethod(LinearMethodBase):
                 return torch.nn.functional.linear(x, weight_bf16.t(), bias)
 
         if self.use_marlin:
-            if self.block_quant:
-                weight_scale = layer.weight_scale_inv
-            else:
-                weight_scale = layer.weight_scale
-
-            return apply_fp8_marlin_linear(
-                input=x,
-                weight=layer.weight,
-                weight_scale=weight_scale,
-                workspace=layer.workspace,
-                size_n=layer.output_size_per_partition,
-                size_k=layer.input_size_per_partition,
-                input_dtype=self.marlin_input_dtype,
-                bias=bias,
-            )
+            return self.fp8_linear.apply_weights(layer, x, bias)
 
         if self.block_quant:
             assert self.weight_block_size is not None
@@ -623,18 +599,20 @@ class Fp8OnlineLinearMethod(Fp8LinearMethod):
 
         layer.input_scale = None
         qweight, weight_scale = ops.scaled_fp8_quant(layer.weight, scale=None)
-        weight = qweight.t()
 
         # Update layer with new values.
-        replace_parameter(layer, "weight", weight.data)
+        replace_parameter(layer, "weight", qweight.data)
         replace_parameter(layer, "weight_scale", weight_scale.data)
 
         if self.use_marlin:
-            size_k_first = True
-            prepare_fp8_layer_for_marlin(
-                layer, size_k_first, input_dtype=self.marlin_input_dtype
-            )
-            # Activations not quantized for marlin.
+            # Only Marlin kernels support `marlin_input_dtype`; guard to avoid
+            # AttributeError if backend selection changes.
+            if hasattr(self.fp8_linear, "marlin_input_dtype"):
+                self.fp8_linear.marlin_input_dtype = self.marlin_input_dtype
+            self.fp8_linear.process_weights_after_loading(layer)
+        else:
+            weight = qweight.t()
+            replace_parameter(layer, "weight", weight.data)
 
         # Prevent duplicate processing (e.g., during weight reload)
         layer._already_called_process_weights_after_loading = True