cudaMemcpyToSymbol使用

 

学到了cudaMemcpyToSymbol竟然还有将数据从host拷贝到global的功能，以前只用过这个函数拷贝到constant memory。拷贝方式的不同是由目的内存申请的方式决定的。

申请的是device内存，cudaMemcpyToSymbol拷贝就是从host拷贝到global memory。

申请的是constant内存，cudaMemcpyToSymbol拷贝就是从host拷贝到constant memory。

__device__ float g_damp_x[MAX_DIM];
__constant__ float c_damp_y[MAX_DIM];

 

main.cu

#include "error.cuh"
#include <stdio.h>
__device__ int d_x = 1;
__device__ int d_y[2];

void __global__ my_kernel(void)
{
    d_y[0] += d_x;
    d_y[1] += d_x;
    printf("d_x = %d, d_y[0] = %d, d_y[1] = %d.\n", d_x, d_y[0], d_y[1]);
}

int main(void)
{
    int h_y[2] = {10, 20};
    CHECK(cudaMemcpyToSymbol(d_y, h_y, sizeof(int) * 2));
    
    my_kernel<<<1, 1>>>();
    CHECK(cudaDeviceSynchronize());
    
    CHECK(cudaMemcpyFromSymbol(h_y, d_y, sizeof(int) * 2));
    printf("h_y[0] = %d, h_y[1] = %d.\n", h_y[0], h_y[1]);
    
    return 0;
}

 

#pragma once
#include <stdio.h>

#define CHECK(call)                                   \
do                                                    \
{                                                     \
    const cudaError_t error_code = call;              \
    if (error_code != cudaSuccess)                    \
    {                                                 \
        printf("CUDA Error:\n");                      \
        printf("    File:       %s\n", __FILE__);     \
        printf("    Line:       %d\n", __LINE__);     \
        printf("    Error code: %d\n", error_code);   \
        printf("    Error text: %s\n",                \
            cudaGetErrorString(error_code));          \
        exit(1);                                      \
    }                                                 \
} while (0)

参考：

https://blog.youkuaiyun.com/u014800094/article/details/53994933?utm_source=blogxgwz5