Feature/silu block quant fusion v1 (#32996)

Signed-off-by: Monishver Chandrasekaran <monishverchandrasekaran@gmail.com>

CMakeLists.txt

@@ -340,7 +340,8 @@ if(VLLM_GPU_LANG STREQUAL "CUDA")
 
   list(APPEND VLLM_EXT_SRC
     "csrc/quantization/awq/gemm_kernels.cu"
-    "csrc/cutlass_extensions/common.cpp")
+    "csrc/cutlass_extensions/common.cpp"
+    "csrc/quantization/fused_kernels/fused_silu_mul_block_quant.cu")
 
   set_gencode_flags_for_srcs(
     SRCS "${VLLM_EXT_SRC}"

benchmarks/fused_kernels/silu_mul_block_quant_benchmark.py

@@ -0,0 +1,211 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: Copyright contributors to the vLLM project
+
+from collections.abc import Callable, Iterable
+from dataclasses import dataclass
+from itertools import product
+
+import torch
+import torch.nn.functional as F
+import torch.utils.benchmark as TBenchmark
+from torch.utils.benchmark import Measurement as TMeasurement
+from tqdm import tqdm
+
+import vllm._custom_ops as ops
+from vllm.model_executor.layers.quantization.utils.fp8_utils import (
+    per_token_group_quant_fp8,
+)
+
+
+@dataclass
+class bench_params_t:
+    num_tokens: int
+    hidden_size: int
+    dtype: torch.dtype
+    group_size: int  # Changed from list[int] to int
+
+    def description(self):
+        return (
+            f"N {self.num_tokens} "
+            f"x D {self.hidden_size} "
+            f"x DT {self.dtype} "
+            f"x GS {self.group_size}"
+        )
+
+
+def get_bench_params() -> list[bench_params_t]:
+    """Test configurations covering common model sizes."""
+    NUM_TOKENS = [16, 128, 512, 2048]
+    HIDDEN_SIZES = [1024, 2048, 4096, 5120, 14336]  # Common FFN sizes
+    DTYPES = [torch.float16, torch.bfloat16]
+    GROUP_SIZES = [64, 128]  # Changed from [[1, 64], [1, 128]]
+
+    combinations = product(NUM_TOKENS, HIDDEN_SIZES, DTYPES, GROUP_SIZES)
+    bench_params = list(
+        map(lambda x: bench_params_t(x[0], x[1], x[2], x[3]), combinations)
+    )
+    return bench_params
+
+
+# Reference implementations
+def unfused_fp8_impl(
+    x: torch.Tensor,
+    quant_dtype: torch.dtype,
+    group_size: int,  # Changed from list[int]
+):
+    """Unfused: SiLU+Mul then per-tensor quantize."""
+    hidden = x.shape[-1] // 2
+    gate, up = x.split(hidden, dim=-1)
+
+    # SiLU(gate) * up
+    silu_out = F.silu(gate) * up
+
+    # Per-tensor quantize (no group_size used here)
+    silu_out, _ = ops.scaled_fp8_quant(silu_out)
+
+
+def unfused_groupwise_fp8_impl(
+    x: torch.Tensor,
+    quant_dtype: torch.dtype,
+    group_size: int,  # Changed from list[int]
+):
+    """Unfused: SiLU+Mul then group-wise quantize."""
+    hidden = x.shape[-1] // 2
+    gate, up = x.split(hidden, dim=-1)
+
+    # SiLU(gate) * up
+    silu_out = F.silu(gate) * up
+
+    # Group quantize - use group_size directly
+    silu_out, _ = per_token_group_quant_fp8(
+        silu_out, group_size=group_size, use_ue8m0=False
+    )
+
+
+def fused_impl(
+    x: torch.Tensor,
+    quant_dtype: torch.dtype,
+    group_size: int,
+):
+    """Fused: SiLU+Mul+Block Quantization in single kernel."""
+    out, _ = ops.silu_and_mul_per_block_quant(
+        x,
+        group_size=group_size,
+        quant_dtype=quant_dtype,
+        is_scale_transposed=False,
+    )
+
+
+# Bench functions
+def bench_fn(
+    x: torch.Tensor,
+    quant_dtype: torch.dtype,
+    group_size: int,
+    label: str,
+    sub_label: str,
+    fn: Callable,
+    description: str,
+) -> TMeasurement:
+    min_run_time = 1
+
+    globals = {
+        "x": x,
+        "quant_dtype": quant_dtype,
+        "group_size": group_size,
+        "fn": fn,
+    }
+    return TBenchmark.Timer(
+        stmt="fn(x, quant_dtype, group_size)",
+        globals=globals,
+        label=label,
+        sub_label=sub_label,
+        description=description,
+    ).blocked_autorange(min_run_time=min_run_time)
+
+
+def bench(params: bench_params_t, label: str, sub_label: str) -> Iterable[TMeasurement]:
+    """Run benchmarks for all implementations."""
+    # Make inputs: [num_tokens, hidden_size * 2] for [gate || up]
+    scale = 1 / params.hidden_size
+    x = (
+        torch.randn(
+            params.num_tokens,
+            params.hidden_size * 2,
+            dtype=params.dtype,
+            device="cuda",
+        )
+        * scale
+    )
+
+    timers = []
+
+    # Unfused per-tensor FP8
+    timers.append(
+        bench_fn(
+            x,
+            torch.float8_e4m3fn,
+            params.group_size,
+            label,
+            sub_label,
+            unfused_fp8_impl,
+            "unfused_fp8_impl",
+        )
+    )
+
+    # Unfused group-wise FP8
+    timers.append(
+        bench_fn(
+            x,
+            torch.float8_e4m3fn,
+            params.group_size,
+            label,
+            sub_label,
+            unfused_groupwise_fp8_impl,
+            "unfused_groupwise_fp8_impl",
+        )
+    )
+
+    # Fused group-wise FP8
+    timers.append(
+        bench_fn(
+            x,
+            torch.float8_e4m3fn,
+            params.group_size,
+            label,
+            sub_label,
+            fused_impl,
+            "fused_groupwise_fp8_impl",
+        )
+    )
+
+    return timers
+
+
+def print_timers(timers: Iterable[TMeasurement]):
+    compare = TBenchmark.Compare(timers)
+    compare.print()
+
+
+def main():
+    torch.set_default_device("cuda")
+    bench_params = get_bench_params()
+
+    print(f"Running {len(bench_params)} benchmark configurations...")
+    print(
+        f"This will take approximately {len(bench_params) * 3} seconds (1s per variant)"
+    )
+    print()
+
+    timers = []
+    for bp in tqdm(bench_params):
+        result_timers = bench(bp, "silu-mul-block-quant", bp.description())
+        timers.extend(result_timers)
+
+    print("\n" + "=" * 80)
+    print("FINAL COMPARISON - ALL RESULTS")
+    print("=" * 80)
+    print_timers(timers)
+
+
+if __name__ == "__main__":
+    main()

csrc/ops.h

@@ -142,6 +142,12 @@ void rms_norm_per_block_quant(torch::Tensor& out, torch::Tensor const& input,
                               std::optional<torch::Tensor> residual,
                               int64_t group_size, bool is_scale_transposed);
 
+void silu_and_mul_per_block_quant(torch::Tensor& out,
+                                  torch::Tensor const& input,
+                                  torch::Tensor& scales, int64_t group_size,
+                                  std::optional<torch::Tensor> scale_ub,
+                                  bool is_scale_transposed);
+
 void rotary_embedding(torch::Tensor& positions, torch::Tensor& query,
                       std::optional<torch::Tensor> key, int64_t head_size,
                       torch::Tensor& cos_sin_cache, bool is_neox);

csrc/quantization/fused_kernels/fused_silu_mul_block_quant.cu

@@ -0,0 +1,169 @@
+// SPDX-License-Identifier: Apache-2.0
+// SPDX-FileCopyrightText: Copyright contributors to the vLLM project
+
+#include <ATen/cuda/CUDAContext.h>
+#include <c10/cuda/CUDAGuard.h>
+
+#include "../../dispatch_utils.h"
+#include "quant_conversions.cuh"
+#include "../w8a8/fp8/common.cuh"
+
+namespace vllm {
+
+// Logic: one thread block per (token, group) pair
+
+template <typename scalar_t, typename scalar_out_t, bool is_scale_transposed,
+          int32_t group_size>
+__global__ void silu_and_mul_per_block_quant_kernel(
+    scalar_out_t* __restrict__ out,  // Output: [num_tokens, hidden_size] in
+                                     // FP8/INT8
+    float* __restrict__ scales,      // Output: [num_tokens, hidden_size /
+                                 // group_size] or [hidden_size / group_size,
+                                 // num_tokens]
+    scalar_t const* __restrict__ input,  // Input: [num_tokens, hidden_size * 2]
+    float const* scale_ub,               // Optional scale upper bound
+    int32_t const hidden_size  // Output hidden size (input is 2x this)
+) {
+  static_assert((group_size & (group_size - 1)) == 0,
+                "group_size must be a power of 2 for correct reduction");
+
+  // Grid: (num_tokens, num_groups)
+  int const token_idx = blockIdx.x;
+  int const group_idx = blockIdx.y;
+  int const tid = threadIdx.x;  // tid in [0, group_size)
+  int const num_tokens = gridDim.x;
+
+  // Input layout: [gate || up] concatenated along last dimension
+  int const input_stride = hidden_size * 2;
+  int const group_start = group_idx * group_size;
+
+  // Pointers to this token's data
+  scalar_t const* token_input_gate =
+      input + token_idx * input_stride + group_start;
+  scalar_t const* token_input_up = token_input_gate + hidden_size;
+  scalar_out_t* token_output = out + token_idx * hidden_size + group_start;
+
+  // Scale pointer for this group
+  int const num_groups = gridDim.y;
+  float* group_scale_ptr = is_scale_transposed
+                               ? scales + group_idx * num_tokens + token_idx
+                               : scales + token_idx * num_groups + group_idx;
+
+  // Shared memory for reduction (compile-time sized)
+  __shared__ float shared_max[group_size];
+
+  // Step 1: Each thread loads one element, computes SiLU, stores in register
+  float gate = static_cast<float>(token_input_gate[tid]);
+  float up = static_cast<float>(token_input_up[tid]);
+
+  // Compute SiLU(gate) * up
+  float sigmoid_gate = 1.0f / (1.0f + expf(-gate));
+  float silu_gate = gate * sigmoid_gate;
+  float result = silu_gate * up;  // Keep in register
+
+  // Step 2: Reduce to find group max
+  shared_max[tid] = fabsf(result);
+  __syncthreads();
+
+// Power-of-2 reduction (group_size guaranteed to be power of 2)
+#pragma unroll
+  for (int stride = group_size / 2; stride > 0; stride >>= 1) {
+    if (tid < stride) {
+      shared_max[tid] = fmaxf(shared_max[tid], shared_max[tid + stride]);
+    }
+    __syncthreads();
+  }
+
+  // Step 3: Compute scale (thread 0), broadcast via shared memory
+  if (tid == 0) {
+    float group_max = shared_max[0];
+
+    float const quant_range = quant_type_max_v<scalar_out_t>;
+    float group_scale = group_max / quant_range;
+
+    // Apply scale upper bound if provided
+    if (scale_ub != nullptr) {
+      group_scale = fminf(group_scale, *scale_ub);
+    }
+
+    // Use minimum safe scaling factor
+    group_scale = fmaxf(group_scale, min_scaling_factor<scalar_out_t>::val());
+
+    // Store scale to global memory
+    *group_scale_ptr = group_scale;
+
+    // Reuse shared_max[0] to broadcast scale
+    shared_max[0] = group_scale;
+  }
+  __syncthreads();
+
+  float group_scale = shared_max[0];
+
+  // Step 4: Quantize and write output
+  token_output[tid] =
+      vllm::ScaledQuant<scalar_out_t, false>::quant_fn(result, group_scale);
+}
+
+}  // namespace vllm
+
+void silu_and_mul_per_block_quant(torch::Tensor& out,
+                                  torch::Tensor const& input,
+                                  torch::Tensor& scales, int64_t group_size,
+                                  std::optional<torch::Tensor> scale_ub,
+                                  bool is_scale_transposed) {
+  static c10::ScalarType kFp8Type = is_fp8_ocp()
+                                        ? c10::ScalarType::Float8_e4m3fn
+                                        : c10::ScalarType::Float8_e4m3fnuz;
+
+  TORCH_CHECK(out.dtype() == kFp8Type || out.dtype() == torch::kInt8);
+  TORCH_CHECK(out.is_contiguous() && input.is_contiguous());
+  TORCH_CHECK(
+      input.dtype() == torch::kFloat16 || input.dtype() == torch::kBFloat16,
+      "Input must be FP16 or BF16");
+  TORCH_CHECK(scales.dtype() == torch::kFloat32, "Scales must be FP32");
+  TORCH_CHECK(group_size == 128 || group_size == 64,
+              "Unsupported group size: ", group_size);
+
+  if (scale_ub.has_value()) {
+    TORCH_CHECK(out.dtype() == kFp8Type);
+  }
+
+  int32_t hidden_size = out.size(-1);
+  auto num_tokens = input.size(0);
+  int32_t num_groups = hidden_size / group_size;
+
+  TORCH_CHECK(input.size(-1) == hidden_size * 2,
+              "input last dim must be 2x output hidden_size");
+  TORCH_CHECK(hidden_size % group_size == 0,
+              "hidden_size must be divisible by group_size");
+
+  const at::cuda::OptionalCUDAGuard device_guard(device_of(input));
+  const cudaStream_t stream = at::cuda::getCurrentCUDAStream();
+
+  dim3 grid(num_tokens, num_groups);
+  dim3 block(group_size);
+
+  VLLM_DISPATCH_FLOATING_TYPES(
+      input.scalar_type(), "silu_and_mul_per_block_quant", [&] {
+        using scalar_in_t = scalar_t;
+
+        VLLM_DISPATCH_QUANT_TYPES(
+            out.scalar_type(), "silu_and_mul_per_block_quant", [&] {
+              using scalar_out_t = scalar_t;
+
+              VLLM_DISPATCH_GROUP_SIZE(group_size, gs, [&] {
+                VLLM_DISPATCH_BOOL(is_scale_transposed, transpose_scale, [&] {
+                  vllm::silu_and_mul_per_block_quant_kernel<
+                      scalar_in_t, scalar_out_t, transpose_scale, gs>
+                      <<<grid, block, 0, stream>>>(
+                          out.data_ptr<scalar_out_t>(),
+                          scales.data_ptr<float>(),
+                          input.data_ptr<scalar_in_t>(),
+                          scale_ub.has_value() ? scale_ub->data_ptr<float>()
+                                               : nullptr,
+                          hidden_size);
+                });
+              });
+            });
+      });
+}

csrc/torch_bindings.cpp

@@ -2,7 +2,6 @@
 #include "cuda_utils.h"
 #include "ops.h"
 #include "core/registration.h"
-
 #include <torch/library.h>
 #include <torch/version.h>
 
@@ -110,6 +109,18 @@ TORCH_LIBRARY_EXPAND(TORCH_EXTENSION_NAME, ops) {
       "silu_and_mul_quant(Tensor! result, Tensor input, Tensor scale) -> ()");
   ops.impl("silu_and_mul_quant", torch::kCUDA, &silu_and_mul_quant);
 
+  // Fused SiLU+Mul + per-block quantization
+  ops.def(
+      "silu_and_mul_per_block_quant("
+      "Tensor! out, "
+      "Tensor input, "
+      "Tensor! scales, "
+      "int group_size, "
+      "Tensor? scale_ub=None, "
+      "bool is_scale_transposed=False) -> ()");
+  ops.impl("silu_and_mul_per_block_quant", torch::kCUDA,
+           &silu_and_mul_per_block_quant);
+
   ops.def("mul_and_silu(Tensor! out, Tensor input) -> ()");
   ops.impl("mul_and_silu", torch::kCUDA, &mul_and_silu);
 

docs/design/fusions.md

@@ -45,7 +45,7 @@ The table below lists the quantization schemes supported by each fusion on each
 | `enable_sp`                  | FP16/BF16, FP8 static†                   | FP16/BF16, FP8 static                    | FP16/BF16†                               | FP16/BF16†    | —                                        |
 | `fuse_gemm_comms`            | FP16/BF16, FP8 static†                   | FP16/BF16, FP8 static                    | FP16/BF16†                               | FP16/BF16†    | —                                        |
 | `fuse_norm_quant`            | FP8 static, FP8 per-token, FP8 per-group | FP8 static, FP8 per-token, FP8 per-group | FP8 static, FP8 per-token, FP8 per-group | —             | FP8 static, FP8 per-token, FP8 per-group |
-| `fuse_act_quant`             | FP8 static, NVFP4                        | FP8 static                               | FP8 static                               | —             | FP8 per-group                            |
+| `fuse_act_quant`             | FP8 static, NVFP4                        | FP8 static, FP8 per-group (128/64)       | FP8 static, FP8 per-group (128/64)       | —             | FP8 per-group                            |
 | `fuse_act_padding`           | —                                        | —                                        | —                                        | —             | FP16/BF16                                |
 
 \* `fuse_attn_quant` support depends on the attention backend in use; not all backends support
@@ -305,6 +305,7 @@ Note that AITER fusions are in a separate pass in `vllm.compilation.passes.fusio
 Supported quantization scheme/hardware combinations:
 
 - FP8 static per-tensor: CUDA & HIP kernel
+- FP8 dynamic per-group (128/64): CUDA kernel (sm89+, not active when DeepGemm is used on sm100+)
 - NVFP4 dynamic: CUDA sm100+ only with FlashInfer
 - FP8 per-token-group (128): ROCm AITER only
 
@@ -313,6 +314,7 @@ Supported quantization scheme/hardware combinations:
 - Pass: [`vllm/compilation/passes/fusion/act_quant_fusion.py`](https://github.com/vllm-project/vllm/blob/main/vllm/compilation/passes/fusion/act_quant_fusion.py)
 - ROCm AITER pass: [`vllm/compilation/passes/fusion/rocm_aiter_fusion.py`](https://github.com/vllm-project/vllm/blob/main/vllm/compilation/passes/fusion/rocm_aiter_fusion.py)
 - CUDA/HIP kernels: [`csrc/quantization/`](https://github.com/vllm-project/vllm/blob/main/csrc/quantization/)
+- Fused SiLU+Mul+BlockQuant kernel: [`csrc/quantization/fused_kernels/fused_silu_mul_block_quant.cu`](https://github.com/vllm-project/vllm/blob/main/csrc/quantization/fused_kernels/fused_silu_mul_block_quant.cu)
 
 ### RMSNorm + Padding (`fuse_act_padding`)
 

tests/compile/fusions_e2e/models.py

@@ -150,9 +150,8 @@ deepseek_v3_fp8 = ModelFusionInfo(
         # - post_attn_layernorm + MLP
         # 2 per MoE layer (remaining) due to MoE wrapping
         rms_quant_fusion=n_layers * 2 + min(3, n_layers),  # add for 3 dense layers
-        # TODO silu+block quant
-        #  act_quant_fusion=min(3, n_layers), # dense layers only
-        act_quant_fusion=0,
+        # silu+block quant
+        act_quant_fusion=min(3, n_layers),  # dense layers only
         # MLA attn + quant not supported yet:
         # https://github.com/vllm-project/vllm/issues/35792
         attn_quant_fusion=0,

tests/compile/passes/test_silu_mul_quant_fusion.py

@@ -1,6 +1,7 @@
 # SPDX-License-Identifier: Apache-2.0
 # SPDX-FileCopyrightText: Copyright contributors to the vLLM project
 import itertools
+from functools import partial
 
 import pytest
 import torch
@@ -34,13 +35,16 @@ from vllm.model_executor.kernels.linear import (
     ROCmFP8ScaledMMLinearKernel,
 )
 from vllm.model_executor.layers.activation import SiluAndMul
+from vllm.model_executor.layers.quantization.input_quant_fp8 import QuantFP8
 from vllm.model_executor.layers.quantization.utils.fp8_utils import W8A8BlockFp8LinearOp
 from vllm.model_executor.layers.quantization.utils.quant_utils import (
     GroupShape,
+    kFp8Dynamic128Sym,
     kFp8StaticTensorSym,
     kNvfp4Dynamic,
 )
 from vllm.platforms import current_platform
+from vllm.utils.deep_gemm import is_deep_gemm_supported
 
 FP8_DTYPE = current_platform.fp8_dtype()
 FP4_DTYPE = torch.uint8
@@ -165,6 +169,48 @@ class TestSiluMulGroupFp8QuantModel(torch.nn.Module):
         return [torch.ops.vllm.rocm_aiter_act_mul_and_fp8_group_quant]
 
 
+class TestSiluMulBlockQuantModel(torch.nn.Module):
+    quant_key = kFp8Dynamic128Sym
+
+    def __init__(self, hidden_size: int, is_scale_transposed: bool = False, **kwargs):
+        super().__init__()
+        self.silu_and_mul = SiluAndMul()
+        self.is_scale_transposed = is_scale_transposed
+        self.quant_fp8 = QuantFP8(
+            static=False,
+            group_shape=GroupShape(1, 128),
+            column_major_scales=is_scale_transposed,
+            compile_native=False,
+        )
+
+        self.enable_silu_mul_custom_op = self.silu_and_mul.enabled()
+        self.enable_quant_fp8_custom_op = self.quant_fp8.enabled()
+
+    def forward(self, x):
+        y = self.silu_and_mul(x)
+        out, scale = self.quant_fp8(y)
+        group_size = self.quant_key.scale.group_shape[1]
+        scale_expanded = scale.repeat_interleave(group_size, dim=1)
+        dequant = out.to(dtype=torch.float32) * scale_expanded
+        return (dequant,)
+
+    def ops_in_model_before(self):
+        ops = []
+        if self.enable_silu_mul_custom_op:
+            ops.append(SILU_MUL_OP)
+        # When silu custom op is disabled, aten.mul.Tensor also appears
+        # in dequant code, so we skip checking it to avoid false positives.
+        ops.append(
+            QUANT_OPS[self.quant_key]
+            if self.enable_quant_fp8_custom_op
+            else torch.ops.aten.reciprocal.default
+        )
+        return ops
+
+    def ops_in_model_after(self):
+        return [FUSED_OPS[self.quant_key]]
+
+
 ROCM_KERNELS = [ROCmFP8ScaledMMLinearKernel, PerTensorTorchFP8ScaledMMLinearKernel]
 CUDA_KERNELS = [
     FlashInferFP8ScaledMMLinearKernel,
@@ -200,6 +246,19 @@ TEST_KERNELS = ROCM_KERNELS if current_platform.is_rocm() else CUDA_KERNELS
                 not current_platform.is_rocm(), reason="ROCm only"
             ),
         ),
+        # Block quant fusion for per-group FP8 (CUDA only).
+        *[
+            pytest.param(
+                partial(TestSiluMulBlockQuantModel, is_scale_transposed=transposed),
+                True,
+                None,
+                marks=pytest.mark.skipif(
+                    not current_platform.is_cuda(), reason="CUDA only"
+                ),
+                id=f"TestSiluMulBlockQuant-transposed={transposed}",
+            )
+            for transposed in [False, True]
+        ],
     ],
 )
 @pytest.mark.skipif(
@@ -213,6 +272,7 @@ def test_fusion_silu_and_mul_quant(
         TestSiluMulFp8QuantModel
         | TestSiluMulNvfp4QuantModel
         | TestSiluMulGroupFp8QuantModel
+        | TestSiluMulBlockQuantModel
     ],
     enable_silu_mul_custom_op: bool,
     enable_quant_fp8_custom_op: bool,
@@ -223,6 +283,12 @@ def test_fusion_silu_and_mul_quant(
         pytest.skip("NVFP4 is not supported on this GPU.")
     if model_class is TestSiluMulGroupFp8QuantModel and not IS_AITER_FOUND:
         pytest.skip("AITER is not supported on this GPU.")
+    if (
+        isinstance(model_class, partial)
+        and model_class.func is TestSiluMulBlockQuantModel
+        and is_deep_gemm_supported()
+    ):
+        pytest.skip("SiluMul+BlockQuant fusion not applicable with DeepGemm")
 
     torch.set_default_device("cuda")
     torch.set_default_dtype(dtype)
@@ -269,11 +335,13 @@ def test_fusion_silu_and_mul_quant(
         result2 = model2(x)
 
         # Check that it gives the same answer
-        if model_class == TestSiluMulFp8QuantModel:
+        if isinstance(model, TestSiluMulFp8QuantModel):
             atol, rtol = 1e-3, 1e-3
-        elif model_class == TestSiluMulNvfp4QuantModel:
+        elif isinstance(model, TestSiluMulNvfp4QuantModel):
             atol, rtol = 1e-1, 1e-1
-        elif model_class == TestSiluMulGroupFp8QuantModel:
+        elif isinstance(
+            model, (TestSiluMulGroupFp8QuantModel, TestSiluMulBlockQuantModel)
+        ):
             atol, rtol = 5e-2, 5e-2
 
         torch.testing.assert_close(

tests/kernels/core/test_fused_silu_mul_block_quant.py

@@ -0,0 +1,189 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: Copyright contributors to the vLLM project
+
+import pytest
+import torch
+import torch.nn.functional as F
+
+import vllm._custom_ops as ops
+from tests.kernels.utils import opcheck
+from vllm.model_executor.layers.quantization.utils.fp8_utils import (
+    per_token_group_quant_fp8,
+)
+from vllm.model_executor.layers.quantization.utils.int8_utils import (
+    per_token_group_quant_int8,
+)
+from vllm.platforms import current_platform
+
+DTYPES = [torch.float16, torch.bfloat16]
+QUANT_DTYPES = [torch.float8_e4m3fn, torch.int8]
+VEC_HIDDEN_SIZES = [1024, 1025, 1027, 1029]
+NUM_TOKENS_HIDDEN_SIZES = [
+    *[(1, i) for i in [64, *VEC_HIDDEN_SIZES, 2048, 5120]],
+    *[(16, i) for i in [64, *VEC_HIDDEN_SIZES, 5120]],
+    *[(128, i) for i in [64, *VEC_HIDDEN_SIZES]],
+    *[(512, i) for i in [64, 5120]],
+]
+SCALE_UBS = [False]
+GROUP_SIZES = [64, 128]
+IS_SCALE_TRANSPOSED = [False, True]
+SEEDS = [0]
+CUDA_DEVICES = [
+    f"cuda:{i}" for i in range(1 if torch.accelerator.device_count() == 1 else 2)
+]
+
+
+def ref_silu_and_mul_per_block_quant(
+    x: torch.Tensor,
+    quant_dtype: torch.dtype,
+    group_size: int,
+) -> tuple[torch.Tensor, torch.Tensor]:
+    """Reference implementation: unfused SiLU+Mul then group quantization."""
+    hidden = x.shape[-1] // 2
+    gate, up = x.split(hidden, dim=-1)
+    silu_out = F.silu(gate) * up
+
+    if quant_dtype == current_platform.fp8_dtype():
+        return per_token_group_quant_fp8(
+            silu_out, group_size=group_size, use_ue8m0=False
+        )
+    elif quant_dtype == torch.int8:
+        return per_token_group_quant_int8(silu_out, group_size=group_size)
+    else:
+        raise ValueError(f"Unsupported quant_dtype: {quant_dtype}")
+
+
+@pytest.mark.parametrize("num_tokens, hidden_size", NUM_TOKENS_HIDDEN_SIZES)
+@pytest.mark.parametrize("has_scale_ub", SCALE_UBS)
+@pytest.mark.parametrize("dtype", DTYPES)
+@pytest.mark.parametrize("quant_dtype", QUANT_DTYPES)
+@pytest.mark.parametrize("group_size", GROUP_SIZES)
+@pytest.mark.parametrize("is_scale_transposed", IS_SCALE_TRANSPOSED)
+@pytest.mark.parametrize("seed", SEEDS)
+@pytest.mark.parametrize("device", CUDA_DEVICES)
+@torch.inference_mode()
+def test_silu_and_mul_per_block_quant(
+    default_vllm_config,
+    num_tokens: int,
+    hidden_size: int,
+    has_scale_ub: bool,
+    dtype: torch.dtype,
+    quant_dtype: torch.dtype,
+    group_size: int,
+    is_scale_transposed: bool,
+    seed: int,
+    device: str,
+) -> None:
+    """Test SiLU+Mul+Block Quantization kernel correctness."""
+    torch.random.manual_seed(seed)
+    torch.set_default_device(device)
+
+    if hidden_size % group_size != 0:
+        return
+
+    if has_scale_ub:
+        pytest.skip("Scale upper bound not yet supported")
+
+    scale = 1 / hidden_size
+    x = torch.randn(num_tokens, hidden_size * 2, dtype=dtype, device=device) * scale
+
+    # Reference implementation
+    ref_out, ref_scales = ref_silu_and_mul_per_block_quant(x, quant_dtype, group_size)
+
+    # Fused kernel implementation
+    ops_out, ops_scales = ops.silu_and_mul_per_block_quant(
+        x, group_size, quant_dtype, None, is_scale_transposed
+    )
+
+    # Check for NaN/Inf
+    assert not torch.isnan(ops_out.float()).any(), "Kernel output contains NaN"
+    assert not torch.isinf(ops_out.float()).any(), "Kernel output contains Inf"
+    assert not torch.isnan(ops_scales).any(), "Kernel scales contain NaN"
+    assert not torch.isinf(ops_scales).any(), "Kernel scales contain Inf"
+
+    # Check dtypes
+    assert ref_out.dtype == quant_dtype
+    assert ops_out.dtype == quant_dtype
+
+    # Check scales match
+    torch.testing.assert_close(ref_scales, ops_scales, rtol=1e-5, atol=1e-5)
+
+    # Check output correctness via dequantized values
+    ref_scales_expanded = ref_scales.repeat_interleave(group_size, dim=1)
+    ops_scales_expanded = ops_scales.repeat_interleave(group_size, dim=1)
+    ref_deq = ref_out.to(dtype=torch.float32) * ref_scales_expanded
+    ops_deq = ops_out.to(dtype=torch.float32) * ops_scales_expanded
+    torch.testing.assert_close(ref_deq, ops_deq, atol=5e-2, rtol=5e-2)
+
+    # opcheck
+    output = torch.empty(num_tokens, hidden_size, device=device, dtype=quant_dtype)
+    num_groups = hidden_size // group_size
+    if is_scale_transposed:
+        scales = torch.empty(num_groups, num_tokens, device=device, dtype=torch.float32)
+    else:
+        scales = torch.empty(num_tokens, num_groups, device=device, dtype=torch.float32)
+    opcheck(
+        torch.ops._C.silu_and_mul_per_block_quant,
+        (output, x, scales, group_size, None, is_scale_transposed),
+    )
+
+
+@pytest.mark.parametrize("dtype", [torch.float16])
+@pytest.mark.parametrize("hidden_size", [4096])
+@pytest.mark.parametrize("num_tokens", [128])
+@pytest.mark.parametrize("group_size", [128])
+def test_silu_block_quant_shapes(
+    default_vllm_config,
+    dtype: torch.dtype,
+    hidden_size: int,
+    num_tokens: int,
+    group_size: int,
+):
+    """Test that output shapes are correct."""
+    torch.set_default_device("cuda")
+    x = torch.randn(num_tokens, hidden_size * 2, dtype=dtype, device="cuda")
+
+    # Row-major scales
+    out, scales = ops.silu_and_mul_per_block_quant(
+        x,
+        group_size=group_size,
+        quant_dtype=torch.float8_e4m3fn,
+        is_scale_transposed=False,
+    )
+    assert out.shape == (num_tokens, hidden_size)
+    assert scales.shape == (num_tokens, hidden_size // group_size)
+
+    # Column-major scales (logical shape same after .t() in _custom_ops)
+    out, scales = ops.silu_and_mul_per_block_quant(
+        x,
+        group_size=group_size,
+        quant_dtype=torch.float8_e4m3fn,
+        is_scale_transposed=True,
+    )
+    assert out.shape == (num_tokens, hidden_size)
+    assert scales.shape == (num_tokens, hidden_size // group_size)
+
+
+@pytest.mark.parametrize("dtype", [torch.float16])
+@pytest.mark.parametrize("batch_size", [1, 16, 256])
+@pytest.mark.parametrize("hidden_size", [1024, 5120, 14336])
+def test_silu_block_quant_edge_cases(
+    default_vllm_config, dtype: torch.dtype, batch_size: int, hidden_size: int
+):
+    """Test edge cases: single token, large batch, large hidden size."""
+    torch.set_default_device("cuda")
+    x = torch.randn(batch_size, hidden_size * 2, dtype=dtype, device="cuda")
+
+    out, scales = ops.silu_and_mul_per_block_quant(
+        x,
+        group_size=128,
+        quant_dtype=torch.float8_e4m3fn,
+        is_scale_transposed=False,
+    )
+
+    assert out.shape == (batch_size, hidden_size)
+    assert out.dtype == torch.float8_e4m3fn
+    assert scales.dtype == torch.float32
+    assert not torch.isnan(out.float()).any()
+    assert not torch.isnan(scales).any()
+    assert not torch.isinf(scales).any()

vllm/_custom_ops.py

@@ -579,6 +579,56 @@ def rms_norm_per_block_quant(
     return output, scales
 
 
+# fused silu_and_mul + block quant
+def silu_and_mul_per_block_quant(
+    input: torch.Tensor,
+    group_size: int,  # Changed from list[int]
+    quant_dtype: torch.dtype,
+    scale_ub: torch.Tensor | None = None,
+    is_scale_transposed: bool = False,
+) -> tuple[torch.Tensor, torch.Tensor]:
+    assert input.ndim == 2, f"input must be 2D [batch, hidden*2], got {input.shape}"
+    assert input.shape[-1] % 2 == 0, (
+        f"input last dim must be even (gate||up layout), got {input.shape[-1]}"
+    )
+
+    # Output is half the width of input (after silu_and_mul)
+    num_tokens = input.shape[0]
+    hidden_size = input.shape[-1] // 2  # Divide by 2 because input is [gate || up]
+
+    # Allocate output tensor (FP8 or INT8)
+    output = torch.empty(
+        (num_tokens, hidden_size), device=input.device, dtype=quant_dtype
+    )
+
+    # Allocate scales tensor
+    num_groups = hidden_size // group_size  # Directly use group_size
+    if is_scale_transposed:
+        scales = torch.empty(
+            (num_groups, num_tokens),
+            device=input.device,
+            dtype=torch.float32,
+        ).t()
+    else:
+        scales = torch.empty(
+            (num_tokens, num_groups),
+            device=input.device,
+            dtype=torch.float32,
+        )
+
+    # Call the C++ kernel
+    torch.ops._C.silu_and_mul_per_block_quant(
+        output,
+        input,
+        scales,
+        group_size,  # Pass directly as int
+        scale_ub,
+        is_scale_transposed,
+    )
+
+    return output, scales
+
+
 # quantization ops
 # awq
 def awq_dequantize(

vllm/compilation/passes/fusion/act_quant_fusion.py

@@ -17,6 +17,8 @@ from vllm.config import VllmConfig
 from vllm.logger import init_logger
 from vllm.model_executor.layers.quantization.utils.quant_utils import (
     QuantKey,
+    kFp8Dynamic64Sym,
+    kFp8Dynamic128Sym,
     kFp8StaticTensorSym,
     kNvfp4Dynamic,
 )
@@ -43,6 +45,10 @@ silu_and_mul_nvfp4_quant_supported = current_platform.is_cuda() and hasattr(
 if silu_and_mul_nvfp4_quant_supported:
     FUSED_OPS[kNvfp4Dynamic] = torch.ops._C.silu_and_mul_nvfp4_quant.default  # noqa: E501
 
+if current_platform.is_cuda():
+    FUSED_OPS[kFp8Dynamic128Sym] = torch.ops._C.silu_and_mul_per_block_quant.default
+    FUSED_OPS[kFp8Dynamic64Sym] = torch.ops._C.silu_and_mul_per_block_quant.default
+
 
 class ActivationQuantPattern(ABC):
     """
@@ -174,6 +180,102 @@ class SiluMulNvfp4QuantPattern(ActivationQuantPattern):
         register_replacement(pattern, replacement, self.get_inputs(), fwd_only, pm_pass)
 
 
+class SiluMulBlockQuantPattern(ActivationQuantPattern):
+    """
+    Fusion for SiluMul+BlockQuant (FP8 dynamic per-group) Pattern.
+    Supports group_size 128 and 64 via QuantKey.
+    Parameterized on is_scale_transposed for different scale layouts.
+    """
+
+    def __init__(
+        self,
+        quant_key: QuantKey,
+        is_scale_transposed: bool = False,
+        is_e8m0: bool = False,
+        is_tma_aligned: bool = False,
+    ) -> None:
+        super().__init__(quant_key)
+        self.quant_matcher = MatcherQuantFP8(
+            quant_key,
+            has_col_major_scales=is_scale_transposed,
+            is_e8m0=is_e8m0,
+            is_tma_aligned=is_tma_aligned,
+        )
+        self.group_size = quant_key.scale.group_shape[1]
+        self.is_scale_transposed = is_scale_transposed
+        self.is_e8m0 = is_e8m0
+        self.is_tma_aligned = is_tma_aligned
+
+    def get_inputs(self) -> list[torch.Tensor]:
+        scale = self.quant_matcher.empty_f32(1, 1)
+        return self.silu_and_mul_matcher.inputs() + [scale]
+
+    def register(self, pm_pass: PatternMatcherPass) -> None:
+        is_scale_transposed = self.is_scale_transposed
+
+        def pattern(
+            input: torch.Tensor,
+            scale: torch.Tensor,
+        ) -> tuple[torch.Tensor, torch.Tensor]:
+            silu_out = self.silu_and_mul_matcher(input)
+            result = torch.empty(
+                silu_out.shape,
+                device=silu_out.device,
+                dtype=self.quant_dtype,
+            )
+            assert scale is not None
+            finfo = torch.finfo(self.quant_dtype)
+            _, result, scale = auto_functionalized(
+                self.quant_matcher.QUANT_OP,
+                input=silu_out,
+                output_q=result,
+                output_s=scale,
+                group_size=self.group_size,
+                eps=1e-10,
+                fp8_min=finfo.min,
+                fp8_max=finfo.max,
+                scale_ue8m0=self.is_e8m0,
+                dummy_is_scale_transposed=is_scale_transposed,
+                dummy_is_tma_aligned=self.is_tma_aligned,
+            )
+            return result, scale
+
+        def replacement(
+            input: torch.Tensor,
+            scale: torch.Tensor,
+        ) -> tuple[torch.Tensor, torch.Tensor]:
+            d = input.shape[-1] // 2
+            output_shape = input.shape[:-1] + (d,)
+            result = torch.empty(
+                output_shape, device=input.device, dtype=self.quant_dtype
+            )
+            if is_scale_transposed:
+                scale = torch.empty(
+                    (d // self.group_size, input.shape[0]),
+                    device=input.device,
+                    dtype=torch.float32,
+                ).permute(-1, -2)
+            else:
+                scale = torch.empty(
+                    (input.shape[0], d // self.group_size),
+                    device=input.device,
+                    dtype=torch.float32,
+                )
+            at = auto_functionalized(
+                self.FUSED_OP,
+                out=result,
+                input=input,
+                scales=scale,
+                group_size=self.group_size,
+                scale_ub=None,
+                is_scale_transposed=is_scale_transposed,
+            )
+            return at[1], at[2]
+
+        inps = self.get_inputs()
+        register_replacement(pattern, replacement, inps, fwd_only, pm_pass)
+
+
 class ActivationQuantFusionPass(VllmPatternMatcherPass):
     """
     This pass fuses a pre-defined set of custom ops into fused ops.
@@ -199,6 +301,18 @@ class ActivationQuantFusionPass(VllmPatternMatcherPass):
             pattern_silu_mul_nvfp4 = SiluMulNvfp4QuantPattern()
             pattern_silu_mul_nvfp4.register(self.patterns)
 
+        if current_platform.is_cuda():
+            for quant_key in [kFp8Dynamic128Sym, kFp8Dynamic64Sym]:
+                for is_scale_transposed in [False, True]:
+                    for is_e8m0 in [True, False]:
+                        for is_tma_aligned in [False, True]:
+                            SiluMulBlockQuantPattern(
+                                quant_key,
+                                is_scale_transposed=is_scale_transposed,
+                                is_e8m0=is_e8m0,
+                                is_tma_aligned=is_tma_aligned,
+                            ).register(self.patterns)
+
         self.dump_patterns(config, self.patterns)
 
     @VllmInductorPass.time_and_log
@@ -212,4 +326,5 @@ class ActivationQuantFusionPass(VllmPatternMatcherPass):
             ActivationQuantPattern,
             SiluMulFp8StaticQuantPattern,
             SiluMulNvfp4QuantPattern,
+            SiluMulBlockQuantPattern,
         )