cublas_trsv_example.cu

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#include <cstdio>
#include <cstdlib>
#include <vector>

#include <cublas_v2.h>
#include <cuda_runtime.h>

#include "cublas_utils.h"

using data_type = double;

int main(int argc, char *argv[]) {
    cublasHandle_t cublasH = NULL;
    cudaStream_t stream = NULL;

    const int m = 2;
    const int n = 2;
    const int lda = m;

    /*
     *   A = | 1.0 2.0 |
     *       | 3.0 4.0 |
     *   x = | 5.0 6.0 |
     */

    const std::vector<data_type> A = {1.0, 3.0, 2.0, 4.0};
    std::vector<data_type> x = {5.0, 6.0};
    const int incx = 1;

    data_type *d_A = nullptr;
    data_type *d_x = nullptr;

    cublasFillMode_t uplo = CUBLAS_FILL_MODE_UPPER;
    cublasOperation_t transa = CUBLAS_OP_N;
    cublasDiagType_t diag = CUBLAS_DIAG_NON_UNIT;

    printf("A\n");
    print_matrix(m, n, A.data(), lda);
    printf("=====\n");

    printf("x\n");
    print_vector(x.size(), x.data());
    printf("=====\n");

    /* step 1: create cublas handle, bind a stream */
    CUBLAS_CHECK(cublasCreate(&cublasH));

    CUDA_CHECK(cudaStreamCreateWithFlags(&stream, cudaStreamNonBlocking));
    CUBLAS_CHECK(cublasSetStream(cublasH, stream));

    /* step 2: copy data to device */
    CUDA_CHECK(cudaMalloc(reinterpret_cast<void **>(&d_A), sizeof(data_type) * A.size()));
    CUDA_CHECK(cudaMalloc(reinterpret_cast<void **>(&d_x), sizeof(data_type) * x.size()));

    CUDA_CHECK(cudaMemcpyAsync(d_A, A.data(), sizeof(data_type) * A.size(), cudaMemcpyHostToDevice,
                               stream));
    CUDA_CHECK(cudaMemcpyAsync(d_x, x.data(), sizeof(data_type) * x.size(), cudaMemcpyHostToDevice,
                               stream));

    /* step 3: compute */
    CUBLAS_CHECK(cublasDtrsv(cublasH, uplo, transa, diag, n, d_A, lda, d_x, incx));

    /* step 4: copy data to host */
    CUDA_CHECK(cudaMemcpyAsync(x.data(), d_x, sizeof(data_type) * x.size(), cudaMemcpyDeviceToHost,
                               stream));

    CUDA_CHECK(cudaStreamSynchronize(stream));

    /*
     *   x = | 2.00 1.50 |
     */

    printf("x\n");
    print_vector(x.size(), x.data());
    printf("=====\n");

    /* free resources */
    CUDA_CHECK(cudaFree(d_A));
    CUDA_CHECK(cudaFree(d_x));

    CUBLAS_CHECK(cublasDestroy(cublasH));

    CUDA_CHECK(cudaStreamDestroy(stream));

    CUDA_CHECK(cudaDeviceReset());

    return EXIT_SUCCESS;
}