cuBLAS cublasSgemv “分段错误”

Question

当运行 cublasSegmv.My GPU 是 K20Xm.Here 是我的代码时，我遇到了分段错误。

float *a, *x, *y;
int NUM_VEC = 8;
y = (float*)malloc(sizeof(float) * rows * NUM_VEC);
a = (float*)malloc(sizeof(float) * rows * cols);
x = (float*)malloc(sizeof(float) * cols * NUM_VEC);
get_mat_random(a, rows, cols);
get_vec_random(x, cols * NUM_VEC);

float *d_a = 0;
float *d_x = 0;
float *d_y = 0;

cudaMalloc((void **)&d_a, rows * cols * sizeof(float);
cudaMalloc((void **)&d_x, cols * NUM_VEC * sizeof(float);
cudaMalloc((void **)&d_y, rows * NUM_VEC * sizeof(float);
cublasSetVector(rows * cols, sizeof(float), a, 1, d_a, 1);
cublasSetVector(NUM_VEC * cols, sizeof(float), x, 1, d_x, 1);
cublasSetVector(NUM_VEC * rows, sizeof(float), y, 1, d_y, 1);
float alpha = 1.0f;
for (int i = 0; i < NUM_VEC; i++) {
  cublasSgemv(handle, CUBLAS_OP_T, cols, rows, &alpha, d_a, rows, d_x + i * cols, 1,0, d_y + i * rows, 1);
}

Answer 1

在我有限的测试中，错误是因为cublasSgemv的beta参数不能是NULL。您应该在主机或设备上为 beta 变量分配内存。以下是我用来重现和修复错误的代码。

#include <cstdio>
#include <iostream>
#include <cuda_runtime.h>
#include <cublas_v2.h>
#include <cstdlib>

using namespace std;

void get_vec_random(float* a, int count)
{
    for(int i=0; i<count; i++)
        a[i] = rand() / float(RAND_MAX);    
}

void get_mat_random(float* a, int rows, int cols)
{
    get_vec_random(a, rows * cols);
}

int main(int argc, char** argv)
{
    int rows = 10, cols = 10;

    cublasHandle_t handle;
    cublasCreate(&handle);


    float *a, *x, *y;
    int NUM_VEC = 8;
    y = (float*)malloc(sizeof(float) * rows * NUM_VEC);
    a = (float*)malloc(sizeof(float) * rows * cols);
    x = (float*)malloc(sizeof(float) * cols * NUM_VEC);
    get_mat_random(a, rows, cols);
    get_vec_random(x, cols * NUM_VEC);

    float *d_a = 0;
    float *d_x = 0;
    float *d_y = 0;

    cudaMalloc((void **)&d_a, rows * cols * sizeof(float));
    cudaMalloc((void **)&d_x, cols * NUM_VEC * sizeof(float));
    cudaMalloc((void **)&d_y, rows * NUM_VEC * sizeof(float));


    cublasSetVector(rows * cols, sizeof(float), a, 1, d_a, 1);
    cublasSetVector(NUM_VEC * cols, sizeof(float), x, 1, d_x, 1);
    cublasSetVector(NUM_VEC * rows, sizeof(float), y, 1, d_y, 1);

    float alpha = 1.0f, beta = 1.0f;

    cublasSetPointerMode(handle, CUBLAS_POINTER_MODE_HOST);
    for (int i = 0; i < NUM_VEC; i++) 
    {
        cublasSgemv(handle, 
                    CUBLAS_OP_T, 
                    cols, 
                    rows, 
                    &alpha, 
                    d_a, 
                    rows, 
                    d_x + i * cols, 
                    1, 
                    &beta, 
                    d_y + i * rows, 
                    1);
    }
    return 0;
}

希望这能解决问题。

cuBLAS cublasSgemv “分段错误”

cuBLAS cublasSgemv “Segmentation fault"

c++

cuda

gpu

cublas