cutlass/include/cutlass/gemm/kernel/gemm.h
Vijay Thakkar 277bd6e537
CUTLASS 3.0.0 (#786)
* CUTLASS 3.0.0
2023-01-23 20:55:28 -05:00

381 lines
13 KiB
C++

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/*! \file
\brief Template for a pipelined GEMM kernel. Does not compute batching or support split-K.
*/
#pragma once
#include "cutlass/cutlass.h"
#include "cutlass/gemm/gemm.h"
#include "cutlass/matrix_coord.h"
#include "cutlass/semaphore.h"
#include "cutlass/arch/arch.h"
/////////////////////////////////////////////////////////////////////////////////////////////////
namespace cutlass {
namespace gemm {
namespace kernel {
/////////////////////////////////////////////////////////////////////////////////////////////////
template <
typename Mma_, ///! Threadblock-scoped matrix multiply-accumulate
typename Epilogue_, ///! Epilogue
typename ThreadblockSwizzle_, ///! Threadblock swizzling function
bool SplitKSerial ///! If true, code supporting split-K via serial reduction is enabled.
>
struct Gemm {
using Mma = Mma_;
using Epilogue = Epilogue_;
using OutputOp = typename Epilogue::OutputOp;
using ThreadblockSwizzle = ThreadblockSwizzle_;
static bool const kSplitKSerial = SplitKSerial;
/// Warp count (concept: GemmShape)
using WarpCount = typename Mma::WarpCount;
static int const kThreadCount = 32 * WarpCount::kCount;
/// Parameters structure
struct Params {
cutlass::gemm::GemmCoord problem_size;
cutlass::gemm::GemmCoord grid_tiled_shape;
int swizzle_log_tile;
typename Mma::IteratorA::Params params_A;
typename Mma::IteratorA::TensorRef ref_A;
typename Mma::IteratorB::Params params_B;
typename Mma::IteratorB::TensorRef ref_B;
typename Epilogue::OutputTileIterator::Params params_C;
typename Epilogue::OutputTileIterator::TensorRef ref_C;
typename Epilogue::OutputTileIterator::Params params_D;
typename Epilogue::OutputTileIterator::TensorRef ref_D;
typename OutputOp::Params output_op;
int *semaphore;
int gemm_k_size;
// For gather+scatter operations
int const *gather_A_indices;
int const *gather_B_indices;
int const *scatter_D_indices;
//
// Methods
//
CUTLASS_HOST_DEVICE
Params(): swizzle_log_tile(0), semaphore(0), gemm_k_size(0) { }
CUTLASS_HOST_DEVICE
Params(
cutlass::gemm::GemmCoord const & problem_size,
cutlass::gemm::GemmCoord const & grid_tiled_shape,
typename Mma::IteratorA::TensorRef ref_A,
typename Mma::IteratorB::TensorRef ref_B,
typename Epilogue::OutputTileIterator::TensorRef ref_C,
typename Epilogue::OutputTileIterator::TensorRef ref_D,
typename OutputOp::Params output_op = typename OutputOp::Params(),
int *workspace = nullptr,
int const *gather_A_indices = nullptr,
int const *gather_B_indices = nullptr,
int const *scatter_D_indices = nullptr
):
problem_size(problem_size),
grid_tiled_shape(grid_tiled_shape),
swizzle_log_tile(ThreadblockSwizzle().get_log_tile(grid_tiled_shape)),
params_A(ref_A.layout()),
ref_A(ref_A),
params_B(ref_B.layout()),
ref_B(ref_B),
params_C(ref_C.layout()),
ref_C(ref_C),
params_D(ref_D.layout()),
ref_D(ref_D),
output_op(output_op),
gather_A_indices(gather_A_indices),
gather_B_indices(gather_B_indices),
scatter_D_indices(scatter_D_indices) {
int total_gemm_k_iterations = (problem_size.k() + Mma::Shape::kK - 1) / Mma::Shape::kK;
int gemm_k_iterations = (total_gemm_k_iterations + grid_tiled_shape.k() - 1) / grid_tiled_shape.k();
gemm_k_size = gemm_k_iterations * Mma::Shape::kK;
semaphore = workspace;
}
};
/// Shared memory storage structure
union SharedStorage {
typename Mma::SharedStorage main_loop;
typename Epilogue::SharedStorage epilogue;
};
//
// Methods
//
CUTLASS_HOST_DEVICE
Gemm() { }
/// Determines whether kernel satisfies alignment
CUTLASS_HOST_DEVICE
static Status can_implement(
cutlass::gemm::GemmCoord const & problem_size,
typename Mma::IteratorA::TensorRef ref_A,
typename Mma::IteratorB::TensorRef ref_B,
typename Epilogue::OutputTileIterator::TensorRef ref_C,
typename Epilogue::OutputTileIterator::TensorRef ref_D) {
static int const kAlignmentA = (platform::is_same<typename Mma::IteratorA::Layout,
layout::ColumnMajorInterleaved<32>>::value)
? 32
: (platform::is_same<typename Mma::IteratorA::Layout,
layout::ColumnMajorInterleaved<64>>::value)
? 64
: Mma::IteratorA::AccessType::kElements;
static int const kAlignmentB = (platform::is_same<typename Mma::IteratorB::Layout,
layout::RowMajorInterleaved<32>>::value)
? 32
: (platform::is_same<typename Mma::IteratorB::Layout,
layout::RowMajorInterleaved<64>>::value)
? 64
: Mma::IteratorB::AccessType::kElements;
static int const kAlignmentC = (platform::is_same<typename Epilogue::OutputTileIterator::Layout,
layout::ColumnMajorInterleaved<32>>::value)
? 32
: (platform::is_same<typename Epilogue::OutputTileIterator::Layout,
layout::ColumnMajorInterleaved<64>>::value)
? 64
: Epilogue::OutputTileIterator::kElementsPerAccess;
if (!TensorRef_aligned(ref_A, kAlignmentA)) {
return Status::kErrorMisalignedOperand;
}
if (!TensorRef_aligned(ref_B, kAlignmentB)) {
return Status::kErrorMisalignedOperand;
}
if (!TensorRef_aligned(ref_C, kAlignmentC)) {
return Status::kErrorMisalignedOperand;
}
if (!TensorRef_aligned(ref_D, kAlignmentC)) {
return Status::kErrorMisalignedOperand;
}
return Status::kSuccess;
}
/// Executes one GEMM
CUTLASS_DEVICE
void operator()(Params const &params, SharedStorage &shared_storage) {
// Compute threadblock location
ThreadblockSwizzle threadblock_swizzle;
cutlass::gemm::GemmCoord threadblock_tile_offset =
threadblock_swizzle.get_tile_offset(params.swizzle_log_tile);
// Early exit if CTA is out of range
if (params.grid_tiled_shape.m() <= threadblock_tile_offset.m() ||
params.grid_tiled_shape.n() <= threadblock_tile_offset.n()) {
return;
}
// Compute initial location in logical coordinates
cutlass::MatrixCoord tb_offset_A{
threadblock_tile_offset.m() * Mma::Shape::kM,
threadblock_tile_offset.k() * params.gemm_k_size,
};
cutlass::MatrixCoord tb_offset_B{
threadblock_tile_offset.k() * params.gemm_k_size,
threadblock_tile_offset.n() * Mma::Shape::kN
};
// Problem size is a function of threadblock index in the K dimension
int problem_size_k = min(
params.problem_size.k(),
(threadblock_tile_offset.k() + 1) * params.gemm_k_size);
// Compute threadblock-scoped matrix multiply-add
int gemm_k_iterations = (problem_size_k - tb_offset_A.column() + Mma::Shape::kK - 1) / Mma::Shape::kK;
// Compute position within threadblock
int thread_idx = threadIdx.x;
// Construct iterators to A and B operands
typename Mma::IteratorA iterator_A(
params.params_A,
params.ref_A.data(),
{params.problem_size.m(), problem_size_k},
thread_idx,
tb_offset_A,
params.gather_A_indices);
typename Mma::IteratorB iterator_B(
params.params_B,
params.ref_B.data(),
{problem_size_k, params.problem_size.n()},
thread_idx,
tb_offset_B,
params.gather_B_indices);
// Broadcast the warp_id computed by lane 0 to ensure dependent code
// is compiled as warp-uniform.
int warp_idx = canonical_warp_idx();
int lane_idx = threadIdx.x % 32;
//
// Main loop
//
// Construct thread-scoped matrix multiply
Mma mma(shared_storage.main_loop, thread_idx, warp_idx, lane_idx);
typename Mma::FragmentC accumulators;
accumulators.clear();
if (!kSplitKSerial || gemm_k_iterations > 0) {
// Compute threadblock-scoped matrix multiply-add
mma(gemm_k_iterations, accumulators, iterator_A, iterator_B, accumulators);
}
//
// Epilogue
//
OutputOp output_op(params.output_op);
//
// Masked tile iterators constructed from members
//
threadblock_tile_offset =
threadblock_swizzle.get_tile_offset(params.swizzle_log_tile);
//assume identity swizzle
MatrixCoord threadblock_offset(
threadblock_tile_offset.m() * Mma::Shape::kM,
threadblock_tile_offset.n() * Mma::Shape::kN
);
int block_idx = threadblock_tile_offset.m() + threadblock_tile_offset.n() * params.grid_tiled_shape.m();
// Construct the semaphore.
Semaphore semaphore(params.semaphore + block_idx, thread_idx);
// If performing a reduction via split-K, fetch the initial synchronization
if (kSplitKSerial && params.grid_tiled_shape.k() > 1) {
// Fetch the synchronization lock initially but do not block.
semaphore.fetch();
// Indicate which position in a serial reduction the output operator is currently updating
output_op.set_k_partition(threadblock_tile_offset.k(), params.grid_tiled_shape.k());
}
// Tile iterator loading from source tensor.
typename Epilogue::OutputTileIterator iterator_C(
params.params_C,
params.ref_C.data(),
params.problem_size.mn(),
thread_idx,
threadblock_offset,
params.scatter_D_indices
);
// Tile iterator writing to destination tensor.
typename Epilogue::OutputTileIterator iterator_D(
params.params_D,
params.ref_D.data(),
params.problem_size.mn(),
thread_idx,
threadblock_offset,
params.scatter_D_indices
);
Epilogue epilogue(
shared_storage.epilogue,
thread_idx,
warp_idx,
lane_idx);
// Wait on the semaphore - this latency may have been covered by iterator construction
if (kSplitKSerial && params.grid_tiled_shape.k() > 1) {
// For subsequent threadblocks, the source matrix is held in the 'D' tensor.
if (threadblock_tile_offset.k()) {
iterator_C = iterator_D;
}
semaphore.wait(threadblock_tile_offset.k());
}
// Execute the epilogue operator to update the destination tensor.
epilogue(output_op, iterator_D, accumulators, iterator_C);
//
// Release the semaphore
//
if (kSplitKSerial && params.grid_tiled_shape.k() > 1) {
int lock = 0;
if (params.grid_tiled_shape.k() == threadblock_tile_offset.k() + 1) {
// The final threadblock resets the semaphore for subsequent grids.
lock = 0;
}
else {
// Otherwise, the semaphore is incremented
lock = threadblock_tile_offset.k() + 1;
}
semaphore.release(lock);
}
}
};
/////////////////////////////////////////////////////////////////////////////////////////////////
} // namespace kernel
} // namespace gemm
} // namespace cutlass