GPU: Add library dispatch module (DeviceMatrix, cuBLAS, cuSOLVER)

Add Eigen/GPU module: A standalone GPU library dispatch layer where
DeviceMatrix<Scalar> operations map 1:1 to cuBLAS/cuSOLVER calls.
CPU and GPU solvers coexist in the same binary with compatible syntax.

Core infrastructure:
- DeviceMatrix<Scalar>: RAII dense column-major GPU memory wrapper with
  async host transfer (fromHost/toHost) and CUDA event-based cross-stream
  synchronization.
- GpuContext: Unified execution context owning a CUDA stream + cuBLAS
  handle + cuSOLVER handle. Thread-local default with explicit override
  via setThreadLocal(). Stream-borrowing constructor for integration.
- DeviceBuffer: Typed RAII device allocation with move semantics.

cuBLAS dispatch (expression syntax):
- GEMM: d_C = d_A.adjoint() * d_B (cublasXgemm)
- TRSM: d_X = d_A.triangularView<Lower>().solve(d_B) (cublasXtrsm)
- SYMM/HEMM: d_C = d_A.selfadjointView<Lower>() * d_B (cublasXsymm)
- SYRK/HERK: d_C = d_A * d_A.adjoint() (cublasXsyrk)

cuSOLVER dispatch:
- GpuLLT: Cached Cholesky factorization (cusolverDnXpotrf + Xpotrs)
- GpuLU: Cached LU factorization (cusolverDnXgetrf + Xgetrs)
- Solver chaining: auto x = d_A.llt().solve(d_B)
- Solver expressions with .device(ctx) for explicit stream control.

CI: Bump CUDA container to Ubuntu 22.04 (CMake 3.22), GCC 10->11,
Clang 12->14. Bump cmake_minimum_required to 3.17 for FindCUDAToolkit.

Tests: gpu_cublas.cpp, gpu_cusolver_llt.cpp, gpu_cusolver_lu.cpp,
gpu_device_matrix.cpp, gpu_library_example.cu
Benchmarks: bench_gpu_solvers.cpp, bench_gpu_chaining.cpp,
bench_gpu_batching.cpp
This commit is contained in:
Rasmus Munk Larsen
2026-04-09 16:15:39 -07:00
parent 6a9405bf7a
commit 58c44ef36d
30 changed files with 5680 additions and 24 deletions

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@@ -43,3 +43,10 @@ add_subdirectory(Householder)
add_subdirectory(Solvers)
add_subdirectory(Tuning)
add_subdirectory(BLAS)
# GPU benchmarks have their own CMake project (needs CUDAToolkit).
# They can also be built standalone: cmake -B build -S benchmarks/GPU
find_package(CUDAToolkit QUIET)
if(CUDAToolkit_FOUND)
add_subdirectory(GPU)
endif()

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@@ -0,0 +1,53 @@
# GPU benchmarks require CUDA runtime + cuSOLVER.
# Build separately from the main benchmark tree since they need CUDA toolchain.
#
# Usage:
# cmake -G Ninja -B build-bench-gpu -S benchmarks/GPU \
# -DCMAKE_CUDA_ARCHITECTURES=89
# cmake --build build-bench-gpu
#
# Profiling:
# nsys profile --trace=cuda ./build-bench-gpu/bench_gpu_solvers
# ncu --set full -o profile ./build-bench-gpu/bench_gpu_solvers --benchmark_filter=BM_GpuLLT_Compute/4096
cmake_minimum_required(VERSION 3.18)
project(EigenGpuBenchmarks CXX)
find_package(benchmark REQUIRED)
find_package(CUDAToolkit REQUIRED)
set(EIGEN_SOURCE_DIR "${CMAKE_CURRENT_SOURCE_DIR}/../..")
function(eigen_add_gpu_benchmark name source)
cmake_parse_arguments(BENCH "" "" "LIBRARIES;DEFINITIONS" ${ARGN})
if(NOT IS_ABSOLUTE "${source}")
set(source "${CMAKE_CURRENT_SOURCE_DIR}/${source}")
endif()
add_executable(${name} ${source})
target_include_directories(${name} PRIVATE
${EIGEN_SOURCE_DIR}
${CUDAToolkit_INCLUDE_DIRS})
target_link_libraries(${name} PRIVATE
benchmark::benchmark benchmark::benchmark_main
CUDA::cudart CUDA::cusolver CUDA::cublas)
if(BENCH_LIBRARIES)
target_link_libraries(${name} PRIVATE ${BENCH_LIBRARIES})
endif()
target_compile_options(${name} PRIVATE -O3 -DNDEBUG)
target_compile_definitions(${name} PRIVATE EIGEN_USE_GPU)
if(BENCH_DEFINITIONS)
target_compile_definitions(${name} PRIVATE ${BENCH_DEFINITIONS})
endif()
endfunction()
# Solver benchmarks: LLT/LU compute + solve, host vs device paths, CPU baselines.
eigen_add_gpu_benchmark(bench_gpu_solvers bench_gpu_solvers.cpp)
eigen_add_gpu_benchmark(bench_gpu_solvers_float bench_gpu_solvers.cpp DEFINITIONS SCALAR=float)
# Chaining benchmarks: async pipeline efficiency, host-roundtrip vs device chain.
eigen_add_gpu_benchmark(bench_gpu_chaining bench_gpu_chaining.cpp)
eigen_add_gpu_benchmark(bench_gpu_chaining_float bench_gpu_chaining.cpp DEFINITIONS SCALAR=float)
# Batching benchmarks: multi-stream concurrency for many small systems.
eigen_add_gpu_benchmark(bench_gpu_batching bench_gpu_batching.cpp)
eigen_add_gpu_benchmark(bench_gpu_batching_float bench_gpu_batching.cpp DEFINITIONS SCALAR=float)

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@@ -0,0 +1,268 @@
// GPU batching benchmarks: multi-stream concurrency for many small solves.
//
// Each GpuLLT/GpuLU owns its own CUDA stream. This benchmark measures how
// well multiple solver instances overlap on the GPU, which is critical for
// workloads like robotics (many small systems) and SLAM (batched poses).
//
// Compares:
// 1. Sequential: one solver handles all systems one by one
// 2. Batched: N solvers on N streams, all launched before any sync
// 3. CPU baseline: Eigen LLT on host
//
// For Nsight Systems: batched mode should show overlapping kernels on
// different streams in the timeline view.
//
// nsys profile --trace=cuda ./bench_gpu_batching
#include <benchmark/benchmark.h>
#include <Eigen/Cholesky>
#include <Eigen/GPU>
#include <memory>
#include <vector>
using namespace Eigen;
#ifndef SCALAR
#define SCALAR double
#endif
using Scalar = SCALAR;
using Mat = Matrix<Scalar, Dynamic, Dynamic>;
static Mat make_spd(Index n) {
Mat M = Mat::Random(n, n);
return M.adjoint() * M + Mat::Identity(n, n) * static_cast<Scalar>(n);
}
static void cuda_warmup() {
static bool done = false;
if (!done) {
void* p;
cudaMalloc(&p, 1);
cudaFree(p);
done = true;
}
}
// --------------------------------------------------------------------------
// Sequential: one solver, N systems solved one after another
// --------------------------------------------------------------------------
static void BM_Batch_Sequential(benchmark::State& state) {
cuda_warmup();
const Index n = state.range(0);
const int batch_size = static_cast<int>(state.range(1));
// Pre-generate all SPD matrices and RHS vectors.
std::vector<Mat> As(batch_size);
std::vector<Mat> Bs(batch_size);
for (int i = 0; i < batch_size; ++i) {
As[i] = make_spd(n);
Bs[i] = Mat::Random(n, 1);
}
GpuLLT<Scalar> llt;
for (auto _ : state) {
std::vector<Mat> results(batch_size);
for (int i = 0; i < batch_size; ++i) {
llt.compute(As[i]);
results[i] = llt.solve(Bs[i]);
}
benchmark::DoNotOptimize(results.back().data());
}
state.counters["n"] = n;
state.counters["batch"] = batch_size;
state.counters["total_solves"] = batch_size;
}
// --------------------------------------------------------------------------
// Sequential with DeviceMatrix (avoid re-upload of A each iteration)
// --------------------------------------------------------------------------
static void BM_Batch_Sequential_Device(benchmark::State& state) {
cuda_warmup();
const Index n = state.range(0);
const int batch_size = static_cast<int>(state.range(1));
std::vector<Mat> As(batch_size);
std::vector<Mat> Bs(batch_size);
std::vector<DeviceMatrix<Scalar>> d_As(batch_size);
std::vector<DeviceMatrix<Scalar>> d_Bs(batch_size);
for (int i = 0; i < batch_size; ++i) {
As[i] = make_spd(n);
Bs[i] = Mat::Random(n, 1);
d_As[i] = DeviceMatrix<Scalar>::fromHost(As[i]);
d_Bs[i] = DeviceMatrix<Scalar>::fromHost(Bs[i]);
}
GpuLLT<Scalar> llt;
for (auto _ : state) {
std::vector<Mat> results(batch_size);
for (int i = 0; i < batch_size; ++i) {
llt.compute(d_As[i]);
DeviceMatrix<Scalar> d_X = llt.solve(d_Bs[i]);
results[i] = d_X.toHost();
}
benchmark::DoNotOptimize(results.back().data());
}
state.counters["n"] = n;
state.counters["batch"] = batch_size;
state.counters["total_solves"] = batch_size;
}
// --------------------------------------------------------------------------
// Batched: N solvers on N streams, overlapping execution
// --------------------------------------------------------------------------
static void BM_Batch_MultiStream(benchmark::State& state) {
cuda_warmup();
const Index n = state.range(0);
const int batch_size = static_cast<int>(state.range(1));
std::vector<Mat> As(batch_size);
std::vector<Mat> Bs(batch_size);
std::vector<DeviceMatrix<Scalar>> d_As(batch_size);
std::vector<DeviceMatrix<Scalar>> d_Bs(batch_size);
for (int i = 0; i < batch_size; ++i) {
As[i] = make_spd(n);
Bs[i] = Mat::Random(n, 1);
d_As[i] = DeviceMatrix<Scalar>::fromHost(As[i]);
d_Bs[i] = DeviceMatrix<Scalar>::fromHost(Bs[i]);
}
// N solvers = N independent CUDA streams.
std::vector<std::unique_ptr<GpuLLT<Scalar>>> solvers(batch_size);
for (int i = 0; i < batch_size; ++i) {
solvers[i] = std::make_unique<GpuLLT<Scalar>>();
}
for (auto _ : state) {
// Phase 1: launch all factorizations (async, different streams).
for (int i = 0; i < batch_size; ++i) {
solvers[i]->compute(d_As[i]);
}
// Phase 2: launch all solves (async, different streams).
std::vector<DeviceMatrix<Scalar>> d_Xs(batch_size);
for (int i = 0; i < batch_size; ++i) {
d_Xs[i] = solvers[i]->solve(d_Bs[i]);
}
// Phase 3: download all results.
std::vector<Mat> results(batch_size);
for (int i = 0; i < batch_size; ++i) {
results[i] = d_Xs[i].toHost();
}
benchmark::DoNotOptimize(results.back().data());
}
state.counters["n"] = n;
state.counters["batch"] = batch_size;
state.counters["streams"] = batch_size;
state.counters["total_solves"] = batch_size;
}
// --------------------------------------------------------------------------
// Batched with async download (overlap D2H with computation)
// --------------------------------------------------------------------------
static void BM_Batch_MultiStream_AsyncDownload(benchmark::State& state) {
cuda_warmup();
const Index n = state.range(0);
const int batch_size = static_cast<int>(state.range(1));
std::vector<Mat> As(batch_size);
std::vector<Mat> Bs(batch_size);
std::vector<DeviceMatrix<Scalar>> d_As(batch_size);
std::vector<DeviceMatrix<Scalar>> d_Bs(batch_size);
for (int i = 0; i < batch_size; ++i) {
As[i] = make_spd(n);
Bs[i] = Mat::Random(n, 1);
d_As[i] = DeviceMatrix<Scalar>::fromHost(As[i]);
d_Bs[i] = DeviceMatrix<Scalar>::fromHost(Bs[i]);
}
std::vector<std::unique_ptr<GpuLLT<Scalar>>> solvers(batch_size);
for (int i = 0; i < batch_size; ++i) {
solvers[i] = std::make_unique<GpuLLT<Scalar>>();
}
for (auto _ : state) {
// Launch all compute + solve.
std::vector<DeviceMatrix<Scalar>> d_Xs(batch_size);
for (int i = 0; i < batch_size; ++i) {
solvers[i]->compute(d_As[i]);
d_Xs[i] = solvers[i]->solve(d_Bs[i]);
}
// Enqueue all async downloads.
std::vector<HostTransfer<Scalar>> transfers;
transfers.reserve(batch_size);
for (int i = 0; i < batch_size; ++i) {
transfers.push_back(d_Xs[i].toHostAsync());
}
// Collect all results.
for (int i = 0; i < batch_size; ++i) {
benchmark::DoNotOptimize(transfers[i].get().data());
}
}
state.counters["n"] = n;
state.counters["batch"] = batch_size;
state.counters["streams"] = batch_size;
state.counters["total_solves"] = batch_size;
}
// --------------------------------------------------------------------------
// CPU baseline: Eigen LLT on host, sequential
// --------------------------------------------------------------------------
static void BM_Batch_CPU(benchmark::State& state) {
const Index n = state.range(0);
const int batch_size = static_cast<int>(state.range(1));
std::vector<Mat> As(batch_size);
std::vector<Mat> Bs(batch_size);
for (int i = 0; i < batch_size; ++i) {
As[i] = make_spd(n);
Bs[i] = Mat::Random(n, 1);
}
for (auto _ : state) {
std::vector<Mat> results(batch_size);
for (int i = 0; i < batch_size; ++i) {
LLT<Mat> llt(As[i]);
results[i] = llt.solve(Bs[i]);
}
benchmark::DoNotOptimize(results.back().data());
}
state.counters["n"] = n;
state.counters["batch"] = batch_size;
state.counters["total_solves"] = batch_size;
}
// --------------------------------------------------------------------------
// Registration
// --------------------------------------------------------------------------
// clang-format off
// Args: {matrix_size, batch_size}
// Small matrices with large batches are the interesting case for multi-stream.
BENCHMARK(BM_Batch_Sequential)->ArgsProduct({{16, 32, 64, 128, 256, 512}, {1, 4, 16, 64}})->Unit(benchmark::kMicrosecond);
BENCHMARK(BM_Batch_Sequential_Device)->ArgsProduct({{16, 32, 64, 128, 256, 512}, {1, 4, 16, 64}})->Unit(benchmark::kMicrosecond);
BENCHMARK(BM_Batch_MultiStream)->ArgsProduct({{16, 32, 64, 128, 256, 512}, {1, 4, 16, 64}})->Unit(benchmark::kMicrosecond);
BENCHMARK(BM_Batch_MultiStream_AsyncDownload)->ArgsProduct({{16, 32, 64, 128, 256, 512}, {1, 4, 16, 64}})->Unit(benchmark::kMicrosecond);
BENCHMARK(BM_Batch_CPU)->ArgsProduct({{16, 32, 64, 128, 256, 512}, {1, 4, 16, 64}})->Unit(benchmark::kMicrosecond);
// Also run larger sizes with moderate batching.
BENCHMARK(BM_Batch_MultiStream)->ArgsProduct({{512, 1024, 2048}, {1, 4, 8}})->Unit(benchmark::kMicrosecond);
BENCHMARK(BM_Batch_MultiStream_AsyncDownload)->ArgsProduct({{512, 1024, 2048}, {1, 4, 8}})->Unit(benchmark::kMicrosecond);
// clang-format on

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@@ -0,0 +1,216 @@
// GPU chaining benchmarks: measure async pipeline efficiency.
//
// Compares:
// 1. Host round-trip per solve (baseline)
// 2. DeviceMatrix chaining (no host round-trip between solves)
// 3. Varying chain lengths (1, 2, 4, 8 consecutive solves)
//
// For Nsight Systems: look for gaps between kernel launches in the timeline.
// Host round-trip creates visible idle gaps; chaining should show back-to-back kernels.
//
// nsys profile --trace=cuda,nvtx ./bench_gpu_chaining
#include <benchmark/benchmark.h>
#include <Eigen/Cholesky>
#include <Eigen/GPU>
using namespace Eigen;
#ifndef SCALAR
#define SCALAR double
#endif
using Scalar = SCALAR;
using Mat = Matrix<Scalar, Dynamic, Dynamic>;
static Mat make_spd(Index n) {
Mat M = Mat::Random(n, n);
return M.adjoint() * M + Mat::Identity(n, n) * static_cast<Scalar>(n);
}
static void cuda_warmup() {
static bool done = false;
if (!done) {
void* p;
cudaMalloc(&p, 1);
cudaFree(p);
done = true;
}
}
// --------------------------------------------------------------------------
// Baseline: host round-trip between every solve
// --------------------------------------------------------------------------
static void BM_Chain_HostRoundtrip(benchmark::State& state) {
cuda_warmup();
const Index n = state.range(0);
const int chain_len = static_cast<int>(state.range(1));
Mat A = make_spd(n);
Mat B = Mat::Random(n, 1);
GpuLLT<Scalar> llt(A);
for (auto _ : state) {
Mat X = B;
for (int i = 0; i < chain_len; ++i) {
X = llt.solve(X); // host → device → host each time
}
benchmark::DoNotOptimize(X.data());
}
state.counters["n"] = n;
state.counters["chain"] = chain_len;
state.counters["solves/iter"] = chain_len;
}
// --------------------------------------------------------------------------
// DeviceMatrix chaining: no host round-trip between solves
// --------------------------------------------------------------------------
static void BM_Chain_Device(benchmark::State& state) {
cuda_warmup();
const Index n = state.range(0);
const int chain_len = static_cast<int>(state.range(1));
Mat A = make_spd(n);
Mat B = Mat::Random(n, 1);
GpuLLT<Scalar> llt(A);
auto d_B = DeviceMatrix<Scalar>::fromHost(B);
for (auto _ : state) {
DeviceMatrix<Scalar> d_X = llt.solve(d_B);
for (int i = 1; i < chain_len; ++i) {
d_X = llt.solve(d_X); // device → device, fully async
}
Mat X = d_X.toHost(); // single sync at end
benchmark::DoNotOptimize(X.data());
}
state.counters["n"] = n;
state.counters["chain"] = chain_len;
state.counters["solves/iter"] = chain_len;
}
// --------------------------------------------------------------------------
// DeviceMatrix chaining with async download (overlap D2H with next iteration)
// --------------------------------------------------------------------------
static void BM_Chain_DeviceAsync(benchmark::State& state) {
cuda_warmup();
const Index n = state.range(0);
const int chain_len = static_cast<int>(state.range(1));
Mat A = make_spd(n);
Mat B = Mat::Random(n, 1);
GpuLLT<Scalar> llt(A);
auto d_B = DeviceMatrix<Scalar>::fromHost(B);
for (auto _ : state) {
DeviceMatrix<Scalar> d_X = llt.solve(d_B);
for (int i = 1; i < chain_len; ++i) {
d_X = llt.solve(d_X);
}
auto transfer = d_X.toHostAsync();
Mat X = transfer.get();
benchmark::DoNotOptimize(X.data());
}
state.counters["n"] = n;
state.counters["chain"] = chain_len;
state.counters["solves/iter"] = chain_len;
}
// --------------------------------------------------------------------------
// Pure GPU chain (no download — measures kernel-only throughput)
// --------------------------------------------------------------------------
static void BM_Chain_DeviceNoDownload(benchmark::State& state) {
cuda_warmup();
const Index n = state.range(0);
const int chain_len = static_cast<int>(state.range(1));
Mat A = make_spd(n);
Mat B = Mat::Random(n, 1);
GpuLLT<Scalar> llt(A);
auto d_B = DeviceMatrix<Scalar>::fromHost(B);
for (auto _ : state) {
DeviceMatrix<Scalar> d_X = llt.solve(d_B);
for (int i = 1; i < chain_len; ++i) {
d_X = llt.solve(d_X);
}
cudaStreamSynchronize(llt.stream());
benchmark::DoNotOptimize(d_X.data());
}
state.counters["n"] = n;
state.counters["chain"] = chain_len;
state.counters["solves/iter"] = chain_len;
}
// --------------------------------------------------------------------------
// Compute + solve chain (full pipeline: factorize, then chain solves)
// --------------------------------------------------------------------------
static void BM_FullPipeline_Host(benchmark::State& state) {
cuda_warmup();
const Index n = state.range(0);
const int chain_len = static_cast<int>(state.range(1));
Mat A = make_spd(n);
Mat B = Mat::Random(n, 1);
for (auto _ : state) {
GpuLLT<Scalar> llt(A);
Mat X = B;
for (int i = 0; i < chain_len; ++i) {
X = llt.solve(X);
}
benchmark::DoNotOptimize(X.data());
}
state.counters["n"] = n;
state.counters["chain"] = chain_len;
}
static void BM_FullPipeline_Device(benchmark::State& state) {
cuda_warmup();
const Index n = state.range(0);
const int chain_len = static_cast<int>(state.range(1));
Mat A = make_spd(n);
Mat B = Mat::Random(n, 1);
for (auto _ : state) {
auto d_A = DeviceMatrix<Scalar>::fromHost(A);
auto d_B = DeviceMatrix<Scalar>::fromHost(B);
GpuLLT<Scalar> llt;
llt.compute(d_A);
DeviceMatrix<Scalar> d_X = llt.solve(d_B);
for (int i = 1; i < chain_len; ++i) {
d_X = llt.solve(d_X);
}
Mat X = d_X.toHost();
benchmark::DoNotOptimize(X.data());
}
state.counters["n"] = n;
state.counters["chain"] = chain_len;
}
// --------------------------------------------------------------------------
// Registration
// --------------------------------------------------------------------------
// clang-format off
// Args: {matrix_size, chain_length}
BENCHMARK(BM_Chain_HostRoundtrip)->ArgsProduct({{64, 256, 1024, 4096}, {1, 2, 4, 8}})->Unit(benchmark::kMicrosecond);
BENCHMARK(BM_Chain_Device)->ArgsProduct({{64, 256, 1024, 4096}, {1, 2, 4, 8}})->Unit(benchmark::kMicrosecond);
BENCHMARK(BM_Chain_DeviceAsync)->ArgsProduct({{64, 256, 1024, 4096}, {1, 2, 4, 8}})->Unit(benchmark::kMicrosecond);
BENCHMARK(BM_Chain_DeviceNoDownload)->ArgsProduct({{64, 256, 1024, 4096}, {1, 2, 4, 8}})->Unit(benchmark::kMicrosecond);
BENCHMARK(BM_FullPipeline_Host)->ArgsProduct({{256, 1024, 4096}, {1, 4}})->Unit(benchmark::kMicrosecond);
BENCHMARK(BM_FullPipeline_Device)->ArgsProduct({{256, 1024, 4096}, {1, 4}})->Unit(benchmark::kMicrosecond);
// clang-format on

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@@ -0,0 +1,296 @@
// GPU solver benchmarks: GpuLLT and GpuLU compute + solve throughput.
//
// Measures factorization and solve performance for the host-matrix and
// DeviceMatrix code paths across a range of matrix sizes.
//
// For Nsight Systems profiling:
// nsys profile --trace=cuda,nvtx ./bench_gpu_solvers
//
// For Nsight Compute kernel analysis:
// ncu --set full -o profile ./bench_gpu_solvers --benchmark_filter=BM_GpuLLT_Compute/4096
#include <benchmark/benchmark.h>
#include <Eigen/Cholesky>
#include <Eigen/GPU>
#include <Eigen/LU>
using namespace Eigen;
#ifndef SCALAR
#define SCALAR double
#endif
using Scalar = SCALAR;
using Mat = Matrix<Scalar, Dynamic, Dynamic>;
// --------------------------------------------------------------------------
// Helpers
// --------------------------------------------------------------------------
static Mat make_spd(Index n) {
Mat M = Mat::Random(n, n);
return M.adjoint() * M + Mat::Identity(n, n) * static_cast<Scalar>(n);
}
// CUDA warm-up: ensure the GPU is initialized before timing.
static void cuda_warmup() {
static bool done = false;
if (!done) {
void* p;
cudaMalloc(&p, 1);
cudaFree(p);
done = true;
}
}
// --------------------------------------------------------------------------
// GpuLLT benchmarks
// --------------------------------------------------------------------------
// Factorize from host matrix (includes H2D upload).
static void BM_GpuLLT_Compute_Host(benchmark::State& state) {
cuda_warmup();
const Index n = state.range(0);
Mat A = make_spd(n);
GpuLLT<Scalar> llt;
for (auto _ : state) {
llt.compute(A);
if (llt.info() != Success) state.SkipWithError("factorization failed");
}
double flops = static_cast<double>(n) * static_cast<double>(n) * static_cast<double>(n) / 3.0;
state.counters["GFLOPS"] =
benchmark::Counter(flops, benchmark::Counter::kIsIterationInvariantRate, benchmark::Counter::kIs1000);
state.counters["n"] = n;
}
// Factorize from DeviceMatrix (D2D copy path).
static void BM_GpuLLT_Compute_Device(benchmark::State& state) {
cuda_warmup();
const Index n = state.range(0);
Mat A = make_spd(n);
auto d_A = DeviceMatrix<Scalar>::fromHost(A);
GpuLLT<Scalar> llt;
for (auto _ : state) {
llt.compute(d_A);
if (llt.info() != Success) state.SkipWithError("factorization failed");
}
double flops = static_cast<double>(n) * static_cast<double>(n) * static_cast<double>(n) / 3.0;
state.counters["GFLOPS"] =
benchmark::Counter(flops, benchmark::Counter::kIsIterationInvariantRate, benchmark::Counter::kIs1000);
state.counters["n"] = n;
}
// Factorize from DeviceMatrix (move path, no copy).
static void BM_GpuLLT_Compute_DeviceMove(benchmark::State& state) {
cuda_warmup();
const Index n = state.range(0);
Mat A = make_spd(n);
GpuLLT<Scalar> llt;
for (auto _ : state) {
auto d_A = DeviceMatrix<Scalar>::fromHost(A);
llt.compute(std::move(d_A));
if (llt.info() != Success) state.SkipWithError("factorization failed");
}
double flops = static_cast<double>(n) * static_cast<double>(n) * static_cast<double>(n) / 3.0;
state.counters["GFLOPS"] =
benchmark::Counter(flops, benchmark::Counter::kIsIterationInvariantRate, benchmark::Counter::kIs1000);
state.counters["n"] = n;
}
// Solve from host matrix (H2D + potrs + D2H).
static void BM_GpuLLT_Solve_Host(benchmark::State& state) {
cuda_warmup();
const Index n = state.range(0);
const Index nrhs = state.range(1);
Mat A = make_spd(n);
Mat B = Mat::Random(n, nrhs);
GpuLLT<Scalar> llt(A);
for (auto _ : state) {
Mat X = llt.solve(B);
benchmark::DoNotOptimize(X.data());
}
state.counters["n"] = n;
state.counters["nrhs"] = nrhs;
}
// Solve from DeviceMatrix (D2D + potrs, async, toHost at end).
static void BM_GpuLLT_Solve_Device(benchmark::State& state) {
cuda_warmup();
const Index n = state.range(0);
const Index nrhs = state.range(1);
Mat A = make_spd(n);
Mat B = Mat::Random(n, nrhs);
GpuLLT<Scalar> llt(A);
auto d_B = DeviceMatrix<Scalar>::fromHost(B);
for (auto _ : state) {
DeviceMatrix<Scalar> d_X = llt.solve(d_B);
Mat X = d_X.toHost();
benchmark::DoNotOptimize(X.data());
}
state.counters["n"] = n;
state.counters["nrhs"] = nrhs;
}
// Solve staying entirely on device (no toHost — measures pure GPU time).
static void BM_GpuLLT_Solve_DeviceOnly(benchmark::State& state) {
cuda_warmup();
const Index n = state.range(0);
const Index nrhs = state.range(1);
Mat A = make_spd(n);
Mat B = Mat::Random(n, nrhs);
GpuLLT<Scalar> llt(A);
auto d_B = DeviceMatrix<Scalar>::fromHost(B);
for (auto _ : state) {
DeviceMatrix<Scalar> d_X = llt.solve(d_B);
// Force completion without D2H transfer.
cudaStreamSynchronize(llt.stream());
benchmark::DoNotOptimize(d_X.data());
}
state.counters["n"] = n;
state.counters["nrhs"] = nrhs;
}
// --------------------------------------------------------------------------
// GpuLU benchmarks
// --------------------------------------------------------------------------
static void BM_GpuLU_Compute_Host(benchmark::State& state) {
cuda_warmup();
const Index n = state.range(0);
Mat A = Mat::Random(n, n);
GpuLU<Scalar> lu;
for (auto _ : state) {
lu.compute(A);
if (lu.info() != Success) state.SkipWithError("factorization failed");
}
double flops = 2.0 / 3.0 * static_cast<double>(n) * static_cast<double>(n) * static_cast<double>(n);
state.counters["GFLOPS"] =
benchmark::Counter(flops, benchmark::Counter::kIsIterationInvariantRate, benchmark::Counter::kIs1000);
state.counters["n"] = n;
}
static void BM_GpuLU_Compute_Device(benchmark::State& state) {
cuda_warmup();
const Index n = state.range(0);
Mat A = Mat::Random(n, n);
auto d_A = DeviceMatrix<Scalar>::fromHost(A);
GpuLU<Scalar> lu;
for (auto _ : state) {
lu.compute(d_A);
if (lu.info() != Success) state.SkipWithError("factorization failed");
}
double flops = 2.0 / 3.0 * static_cast<double>(n) * static_cast<double>(n) * static_cast<double>(n);
state.counters["GFLOPS"] =
benchmark::Counter(flops, benchmark::Counter::kIsIterationInvariantRate, benchmark::Counter::kIs1000);
state.counters["n"] = n;
}
static void BM_GpuLU_Solve_Host(benchmark::State& state) {
cuda_warmup();
const Index n = state.range(0);
const Index nrhs = state.range(1);
Mat A = Mat::Random(n, n);
Mat B = Mat::Random(n, nrhs);
GpuLU<Scalar> lu(A);
for (auto _ : state) {
Mat X = lu.solve(B);
benchmark::DoNotOptimize(X.data());
}
state.counters["n"] = n;
state.counters["nrhs"] = nrhs;
}
static void BM_GpuLU_Solve_Device(benchmark::State& state) {
cuda_warmup();
const Index n = state.range(0);
const Index nrhs = state.range(1);
Mat A = Mat::Random(n, n);
Mat B = Mat::Random(n, nrhs);
GpuLU<Scalar> lu(A);
auto d_B = DeviceMatrix<Scalar>::fromHost(B);
for (auto _ : state) {
DeviceMatrix<Scalar> d_X = lu.solve(d_B);
Mat X = d_X.toHost();
benchmark::DoNotOptimize(X.data());
}
state.counters["n"] = n;
state.counters["nrhs"] = nrhs;
}
// --------------------------------------------------------------------------
// CPU baselines for comparison
// --------------------------------------------------------------------------
static void BM_CpuLLT_Compute(benchmark::State& state) {
const Index n = state.range(0);
Mat A = make_spd(n);
LLT<Mat> llt;
for (auto _ : state) {
llt.compute(A);
benchmark::DoNotOptimize(llt.matrixLLT().data());
}
double flops = static_cast<double>(n) * static_cast<double>(n) * static_cast<double>(n) / 3.0;
state.counters["GFLOPS"] =
benchmark::Counter(flops, benchmark::Counter::kIsIterationInvariantRate, benchmark::Counter::kIs1000);
state.counters["n"] = n;
}
static void BM_CpuLU_Compute(benchmark::State& state) {
const Index n = state.range(0);
Mat A = Mat::Random(n, n);
PartialPivLU<Mat> lu;
for (auto _ : state) {
lu.compute(A);
benchmark::DoNotOptimize(lu.matrixLU().data());
}
double flops = 2.0 / 3.0 * static_cast<double>(n) * static_cast<double>(n) * static_cast<double>(n);
state.counters["GFLOPS"] =
benchmark::Counter(flops, benchmark::Counter::kIsIterationInvariantRate, benchmark::Counter::kIs1000);
state.counters["n"] = n;
}
// --------------------------------------------------------------------------
// Registration
// --------------------------------------------------------------------------
// clang-format off
BENCHMARK(BM_GpuLLT_Compute_Host)->ArgsProduct({{64, 128, 256, 512, 1024, 2048, 4096}})->Unit(benchmark::kMicrosecond);
BENCHMARK(BM_GpuLLT_Compute_Device)->ArgsProduct({{64, 128, 256, 512, 1024, 2048, 4096}})->Unit(benchmark::kMicrosecond);
BENCHMARK(BM_GpuLLT_Compute_DeviceMove)->ArgsProduct({{64, 128, 256, 512, 1024, 2048, 4096}})->Unit(benchmark::kMicrosecond);
BENCHMARK(BM_GpuLLT_Solve_Host)->ArgsProduct({{64, 256, 1024, 4096}, {1, 16}})->Unit(benchmark::kMicrosecond);
BENCHMARK(BM_GpuLLT_Solve_Device)->ArgsProduct({{64, 256, 1024, 4096}, {1, 16}})->Unit(benchmark::kMicrosecond);
BENCHMARK(BM_GpuLLT_Solve_DeviceOnly)->ArgsProduct({{64, 256, 1024, 4096}, {1, 16}})->Unit(benchmark::kMicrosecond);
BENCHMARK(BM_GpuLU_Compute_Host)->ArgsProduct({{64, 128, 256, 512, 1024, 2048, 4096}})->Unit(benchmark::kMicrosecond);
BENCHMARK(BM_GpuLU_Compute_Device)->ArgsProduct({{64, 128, 256, 512, 1024, 2048, 4096}})->Unit(benchmark::kMicrosecond);
BENCHMARK(BM_GpuLU_Solve_Host)->ArgsProduct({{64, 256, 1024, 4096}, {1, 16}})->Unit(benchmark::kMicrosecond);
BENCHMARK(BM_GpuLU_Solve_Device)->ArgsProduct({{64, 256, 1024, 4096}, {1, 16}})->Unit(benchmark::kMicrosecond);
BENCHMARK(BM_CpuLLT_Compute)->ArgsProduct({{64, 128, 256, 512, 1024, 2048, 4096}})->Unit(benchmark::kMicrosecond);
BENCHMARK(BM_CpuLU_Compute)->ArgsProduct({{64, 128, 256, 512, 1024, 2048, 4096}})->Unit(benchmark::kMicrosecond);
// clang-format on