[Kernel] Basic tuned configs for NVFP4 CUTLASS dense GEMM (#20646)

Signed-off-by: mgoin <mgoin64@gmail.com>

csrc/quantization/fp4/nvfp4_scaled_mm_kernels.cu

@@ -30,35 +30,40 @@
 
 #include "cutlass/util/packed_stride.hpp"
 
+#include "core/math.hpp"
+
 using namespace cute;
 
 #if defined(CUTLASS_ARCH_MMA_SM100_SUPPORTED)
-// Kernel Perf config
-template <typename T>
-struct KernelTraits;
 
-template <>
-struct KernelTraits<float> {
-  using MmaTileShape = Shape<_128, _128, _256>;
-  using ClusterShape = Shape<_1, _1, _1>;
-  using PerSmTileShape_MNK = Shape<_128, _128, _256>;
+// Configuration for M in (256, inf)
+struct sm100_fp4_config_default {
+  using KernelSchedule = cutlass::gemm::collective::KernelScheduleAuto;
+  using EpilogueSchedule = cutlass::epilogue::collective::EpilogueScheduleAuto;
+  using TileShape = Shape<_256, _256, _256>;
+  using ClusterShape = Shape<_2, _1, _1>;
+  using PerSmTileShape_MNK = Shape<_128, _256, _256>;
 };
 
-template <>
-struct KernelTraits<cutlass::half_t> {
-  using MmaTileShape = Shape<_256, _256, _256>;
-  using ClusterShape = Shape<_4, _4, _1>;
-  using PerSmTileShape_MNK = Shape<_128, _256, _256>;
+// Configuration for M in (16, 256]
+struct sm100_fp4_config_M256 {
+  using KernelSchedule = cutlass::gemm::collective::KernelScheduleAuto;
+  using EpilogueSchedule = cutlass::epilogue::collective::EpilogueScheduleAuto;
+  using TileShape = Shape<_256, _128, _256>;
+  using ClusterShape = Shape<_2, _1, _1>;
+  using PerSmTileShape_MNK = Shape<_128, _128, _256>;
 };
 
-template <>
-struct KernelTraits<cutlass::bfloat16_t> {
-  using MmaTileShape = Shape<_256, _256, _256>;
-  using ClusterShape = Shape<_4, _4, _1>;
-  using PerSmTileShape_MNK = Shape<_128, _256, _256>;
+// Configuration for M in [1, 16]
+struct sm100_fp4_config_M16 {
+  using KernelSchedule = cutlass::gemm::collective::KernelScheduleAuto;
+  using EpilogueSchedule = cutlass::epilogue::collective::EpilogueScheduleAuto;
+  using TileShape = Shape<_128, _128, _256>;
+  using ClusterShape = Shape<_1, _1, _1>;
+  using PerSmTileShape_MNK = Shape<_128, _128, _256>;
 };
 
-template <typename T>
+template <typename Config, typename OutType>
 struct Fp4GemmSm100 {
   // A matrix configuration
   using ElementA = cutlass::nv_float4_t<cutlass::float_e2m1_t>;
@@ -71,21 +76,22 @@ struct Fp4GemmSm100 {
   static constexpr int AlignmentB = 32;
 
   // C/D matrix configuration
-  using ElementD = T;
-  using ElementC = T;
+  using ElementD = OutType;
+  using ElementC = OutType;
   using LayoutCTag = cutlass::layout::RowMajor;
   using LayoutDTag = cutlass::layout::RowMajor;
   static constexpr int AlignmentD = 128 / cutlass::sizeof_bits<ElementD>::value;
   static constexpr int AlignmentC = 128 / cutlass::sizeof_bits<ElementC>::value;
+
   // Kernel functional config
   using ElementAccumulator = float;
   using ArchTag = cutlass::arch::Sm100;
   using OperatorClass = cutlass::arch::OpClassBlockScaledTensorOp;
 
-  // Kernel Perf config
-  using MmaTileShape = typename KernelTraits<T>::MmaTileShape;
-  using ClusterShape = typename KernelTraits<T>::ClusterShape;
-  using PerSmTileShape_MNK = typename KernelTraits<T>::PerSmTileShape_MNK;
+  // Use config's tile shapes
+  using MmaTileShape = typename Config::TileShape;
+  using ClusterShape = typename Config::ClusterShape;
+  using PerSmTileShape_MNK = typename Config::PerSmTileShape_MNK;
 
   using CollectiveEpilogue =
       typename cutlass::epilogue::collective::CollectiveBuilder<
@@ -119,22 +125,22 @@ struct Fp4GemmSm100 {
   using LayoutD = decltype(cute::make_layout(make_shape(0, 0, 0), StrideD{}));
 };
 
-template <typename T>
-typename T::Gemm::Arguments args_from_options(
+template <typename Config>
+typename Config::Gemm::Arguments args_from_options(
     at::Tensor& D, at::Tensor const& A, at::Tensor const& B,
     at::Tensor const& A_sf, at::Tensor const& B_sf, at::Tensor const& alpha,
     int64_t M, int64_t N, int64_t K) {
-  using ElementA = typename T::Gemm::ElementA;
-  using ElementB = typename T::Gemm::ElementB;
+  using ElementA = typename Config::Gemm::ElementA;
+  using ElementB = typename Config::Gemm::ElementB;
   using ElementSFA = cutlass::float_ue4m3_t;
   using ElementSFB = cutlass::float_ue4m3_t;
-  using ElementD = typename T::Gemm::ElementD;
+  using ElementD = typename Config::Gemm::ElementD;
   using ElementCompute = float;
-  using StrideA = typename T::StrideA;
-  using StrideB = typename T::StrideB;
-  using StrideD = typename T::StrideD;
-  using Sm100BlkScaledConfig =
-      typename T::Gemm::GemmKernel::CollectiveMainloop::Sm1xxBlkScaledConfig;
+  using StrideA = typename Config::StrideA;
+  using StrideB = typename Config::StrideB;
+  using StrideD = typename Config::StrideD;
+  using Sm100BlkScaledConfig = typename Config::Gemm::GemmKernel::
+      CollectiveMainloop::Sm1xxBlkScaledConfig;
 
   int m = static_cast<int>(M);
   int n = static_cast<int>(N);
@@ -148,7 +154,7 @@ typename T::Gemm::Arguments args_from_options(
   auto layout_SFB = Sm100BlkScaledConfig::tile_atom_to_shape_SFB(
       cute::make_shape(m, n, k, 1));
 
-  typename T::Gemm::Arguments arguments{
+  typename Config::Gemm::Arguments arguments{
       cutlass::gemm::GemmUniversalMode::kGemm,
       {m, n, k, 1},
       {// Mainloop arguments
@@ -167,17 +173,17 @@ typename T::Gemm::Arguments args_from_options(
   return arguments;
 }
 
-template <typename T>
+template <typename Config>
 void runGemm(at::Tensor& D, at::Tensor const& A, at::Tensor const& B,
              at::Tensor const& A_sf, at::Tensor const& B_sf,
              at::Tensor const& alpha, int64_t m, int64_t n, int64_t k,
              cudaStream_t stream) {
-  typename Fp4GemmSm100<T>::Gemm gemm;
+  typename Config::Gemm gemm;
 
   auto arguments =
-      args_from_options<Fp4GemmSm100<T>>(D, A, B, A_sf, B_sf, alpha, m, n, k);
+      args_from_options<Config>(D, A, B, A_sf, B_sf, alpha, m, n, k);
 
-  size_t workspace_size = Fp4GemmSm100<T>::Gemm::get_workspace_size(arguments);
+  size_t workspace_size = Config::Gemm::get_workspace_size(arguments);
   auto const workspace_options =
       torch::TensorOptions().dtype(torch::kUInt8).device(A.device());
   auto workspace = torch::empty(workspace_size, workspace_options);
@@ -188,12 +194,40 @@ void runGemm(at::Tensor& D, at::Tensor const& A, at::Tensor const& B,
 
   CUTLASS_CHECK(gemm.run(arguments, workspace.data_ptr(), stream));
 }
+
+// Dispatch function to select appropriate config based on M
+template <typename OutType>
+void cutlass_fp4_gemm_dispatch(torch::Tensor& D, torch::Tensor const& A,
+                               torch::Tensor const& B,
+                               torch::Tensor const& A_sf,
+                               torch::Tensor const& B_sf,
+                               torch::Tensor const& alpha, int64_t m, int64_t n,
+                               int64_t k, cudaStream_t stream) {
+  uint32_t const mp2 = std::max(static_cast<uint32_t>(16), next_pow_2(m));
+
+  if (mp2 <= 16) {
+    // m in [1, 16]
+    runGemm<Fp4GemmSm100<sm100_fp4_config_M16, OutType>>(
+        D, A, B, A_sf, B_sf, alpha, m, n, k, stream);
+  } else if (mp2 <= 256) {
+    // m in (16, 256]
+    runGemm<Fp4GemmSm100<sm100_fp4_config_M256, OutType>>(
+        D, A, B, A_sf, B_sf, alpha, m, n, k, stream);
+  } else {
+    // m in (256, inf)
+    runGemm<Fp4GemmSm100<sm100_fp4_config_default, OutType>>(
+        D, A, B, A_sf, B_sf, alpha, m, n, k, stream);
+  }
+}
+
 #else
-template <typename T>
-void runGemm(at::Tensor& D, at::Tensor const& A, at::Tensor const& B,
-             at::Tensor const& A_sf, at::Tensor const& B_sf,
-             at::Tensor const& alpha, int64_t m, int64_t n, int64_t k,
-             cudaStream_t stream) {
+template <typename OutType>
+void cutlass_fp4_gemm_dispatch(torch::Tensor& D, torch::Tensor const& A,
+                               torch::Tensor const& B,
+                               torch::Tensor const& A_sf,
+                               torch::Tensor const& B_sf,
+                               torch::Tensor const& alpha, int64_t m, int64_t n,
+                               int64_t k, cudaStream_t stream) {
   TORCH_CHECK(false,
               "Unsupported CUTLASS version. Set VLLM_CUTLASS_SRC_DIR to "
               "a CUTLASS 3.8 source directory to enable support.");
@@ -271,12 +305,13 @@ void cutlass_scaled_fp4_mm_sm100a(torch::Tensor& D, torch::Tensor const& A,
   const cudaStream_t stream = at::cuda::getCurrentCUDAStream(A.get_device());
 
   if (out_dtype == at::ScalarType::Half) {
-    runGemm<cutlass::half_t>(D, A, B, A_sf, B_sf, alpha, m, n, k, stream);
+    cutlass_fp4_gemm_dispatch<cutlass::half_t>(D, A, B, A_sf, B_sf, alpha, m, n,
+                                               k, stream);
   } else if (out_dtype == at::ScalarType::BFloat16) {
-    runGemm<cutlass::bfloat16_t>(D, A, B, A_sf, B_sf, alpha, m, n, k, stream);
-  } else if (out_dtype == at::ScalarType::Float) {
-    runGemm<float>(D, A, B, A_sf, B_sf, alpha, m, n, k, stream);
+    cutlass_fp4_gemm_dispatch<cutlass::bfloat16_t>(D, A, B, A_sf, B_sf, alpha,
+                                                   m, n, k, stream);
   } else {
-    TORCH_CHECK(false, "Unsupported output data type of nvfp4 mm");
+    TORCH_CHECK(false, "Unsupported output data type of nvfp4 mm (", out_dtype,
+                ")");
   }
 }