DqMmaMultistage Class — pytorch Architecture

Source Code

aten/src/ATen/native/cuda/cutlass_extensions/gemm/threadblock/dq_mma_multistage.h lines 98–240

class DqMmaMultistage: public DqMmaBase<Shape_, Policy_, typename IteratorScale_::Element, Stages> {
public:
    ///< Base class
    using Base = DqMmaBase<Shape_, Policy_, typename IteratorScale_::Element, Stages>;
    ///< Size of the Gemm problem - concept: gemm::GemmShape<>
    using Shape = Shape_;
    ///< Iterates over tiles of A operand in global memory
    using IteratorA = IteratorA_;
    ///< Iterates over tiles of B operand in global memory
    using IteratorB = IteratorB_;
    ///< Data type of accumulator matrix
    using ElementC = ElementC_;
    ///< Layout of accumulator matrix
    using LayoutC = LayoutC_;
    ///< Policy describing tuning details
    using Policy = Policy_;

    using IteratorScale = IteratorScale_;
    using ElementScale  = typename IteratorScale::Element;
    using LayoutScale   = typename IteratorScale::Layout;

    using SmemIteratorA     = SmemIteratorA_;
    using SmemIteratorB     = SmemIteratorB_;
    using SmemIteratorScale = SmemIteratorScale_;

    static cutlass::arch::CacheOperation::Kind const kCacheOpA = CacheOpA;
    static cutlass::arch::CacheOperation::Kind const kCacheOpB = CacheOpB;

    using TransformBAfterLDS = TransformBAfterLDS_;

    //
    // Dependent types
    //

    /// Fragment of operand Scale loaded from global memory;
    using FragmentScale = typename IteratorScale::Fragment;

    /// Fragment of accumulator tile
    using FragmentC = typename Policy::Operator::FragmentC;

    /// Warp-level Mma
    using Operator = typename Policy::Operator;

    /// Minimum architecture is Sm80 to support cp.async
    using ArchTag = arch::Sm80;

    using Dequantizer =
        warp::MmaTensorOpDequantizer<Operator, typename Base::WarpGemm, Operand::kB, ElementScale, LayoutScale, 32>;

    /// Complex transform on A operand
    static ComplexTransform const kTransformA = Operator::kTransformA;

    /// Complex transform on B operand
    static ComplexTransform const kTransformB = Operator::kTransformB;

    /// Internal structure exposed for introspection.
    struct Detail {

        static_assert(Base::kWarpGemmIterations > 1,
                      "The pipelined structure requires at least two warp-level "
                      "GEMM operations.");

        /// Number of cp.async instructions to load one stage of operand A
        static int const AsyncCopyIterationsPerStageA = IteratorA::ThreadMap::Iterations::kCount;

        /// Number of cp.async instructions to load one stage of operand B
        static int const AsyncCopyIterationsPerStageB = IteratorB::ThreadMap::Iterations::kCount;

        /// Number of stages
        static int const kStages = Stages;

        /// Number of cp.async instructions to load on group of operand A
        static int const kAccessesPerGroupA =
            (AsyncCopyIterationsPerStageA + Base::kWarpGemmIterations - 1) / Base::kWarpGemmIterations;

        /// Number of cp.async instructions to load on group of operand B
        static int const kAccessesPerGroupB =
            (AsyncCopyIterationsPerStageB + Base::kWarpGemmIterations - 1) / Base::kWarpGemmIterations;
    };

private:
    using WarpFragmentA = typename Operator::FragmentA;
    using WarpFragmentB = typename Operator::FragmentB;
    Dequantizer warp_dequantizer_;

    using ElementB          = typename IteratorB::Element;
    using LayoutDetailsForB = kernel::LayoutDetailsB<ElementB, ArchTag>;

    static constexpr bool RequiresTileInterleave =
        layout::IsColumnMajorTileInterleave<typename LayoutDetailsForB::Layout>::value;
    static_assert(!RequiresTileInterleave || (RequiresTileInterleave && (Shape::kK == LayoutDetailsForB::ThreadblockK)),
                  "Layout K must match threadblockK");

private:
    //
    // Data members
    //

    /// Iterator to write threadblock-scoped tile of A operand to shared memory
    SmemIteratorA smem_iterator_A_;

    /// Iterator to write threadblock-scoped tile of B operand to shared memory
    SmemIteratorB smem_iterator_B_;

    /// Iterator to write threadblock-scoped tile of scale operand to shared memory
    SmemIteratorScale smem_iterator_scale_;

public:
    /// Construct from tensor references
    CUTLASS_DEVICE
    DqMmaMultistage(
        ///< Shared storage needed for internal use by threadblock-scoped GEMM
        typename Base::SharedStorage& shared_storage,
        ///< ID within the threadblock
        int thread_idx,
        ///< ID of warp
        int warp_idx,
        ///< ID of each thread within a warp
        int lane_idx):
        Base(shared_storage, thread_idx, warp_idx, lane_idx),
        warp_dequantizer_({shared_storage.operand_scale.data(), LayoutScale(Shape::kN)},
                          (warp_idx % (Base::WarpCount::kM * Base::WarpCount::kN)) / Base::WarpCount::kM,
                          lane_idx),
        smem_iterator_A_(shared_storage.operand_A_ref(), thread_idx),
        smem_iterator_B_(shared_storage.operand_B_ref(), thread_idx),
        smem_iterator_scale_(LayoutScale(Shape::kN), shared_storage.operand_scale.data(), {1, Shape::kN}, thread_idx)
    {
        // Compute warp location within threadblock tile by mapping the warp_id to
        // three coordinates:
        //   _m: the warp's position within the threadblock along the M dimension
        //   _n: the warp's position within the threadblock along the N dimension
        //   _k: the warp's position within the threadblock along the K dimension

        int warp_idx_mn = warp_idx % (Base::WarpCount::kM * Base::WarpCount::kN);
        int warp_idx_k  = warp_idx / (Base::WarpCount::kM * Base::WarpCount::kN);

        int warp_idx_m = warp_idx_mn % Base::WarpCount::kM;
        int warp_idx_n = warp_idx_mn / Base::WarpCount::kM;

        // Add per-warp offsets in units of warp-level tiles
        this->warp_tile_iterator_A_.add_tile_offset({warp_idx_m, Base::kWarpGemmIterations * warp_idx_k});
        this->warp_tile_iterator_B_.add_tile_offset({Base::kWarpGemmIterationsForB * warp_idx_k, warp_idx_n});
    }