從CUDA主機複製陣列到設備

Question

我是CUDA的新手，當我嘗試將陣列從主機複製到設備時出現錯誤。 誤差：無重載的函數 「cudaMalloc」 實例相匹配的參數listargument類型有：（INT（*）[1048576]，無符號​​長整數）

#include <assert.h> 
#include <cuda.h> 
#include <stdio.h> 
#include <stdlib.h> 
#include <stddef.h> 
#include <time.h> 
#include <unistd.h> 
#include <curand.h> 
#include <curand_kernel.h> 



#define N (1024*1024) 
    #define M (1000000) 

/**************************************************/ 
/* this GPU kernel function is used to initialize the random states */ 
__global__ void init(unsigned int seed, curandState_t* states) { 

    /* we have to initialize the state */ 
    curand_init(seed, /* the seed can be the same for each core, here we pass the time in from the CPU */ 
       blockIdx.x, /* the sequence number should be different for each core (unless you want all 
           cores to get the same sequence of numbers for some reason - use thread id! */ 
       0, /* the offset is how much extra we advance in the sequence for each call, can be 0 */ 
       &states[blockIdx.x]); 
} 

/* this GPU kernel takes an array of states, and an array of ints, and puts a random int into each */ 
__global__ void randoms(curandState_t* states, unsigned int* numbers) { 
    /* curand works like rand - except that it takes a state as a parameter */ 
    numbers[blockIdx.x] = curand(&states[blockIdx.x]) %2000; 
}; 

/*******************************************************/ 

    __global__ void cudakernel(int *buf) 
    { 
    int i = threadIdx.x + blockIdx.x * blockDim.x; 
    // buf[i] = rand(); 
    for(int j = 0; j < M; j++) 
     buf[i] = buf[i] * buf[i] - 0.25f; 
    } 

    int main() 

    { 
/*****************************************************/ 
/* CUDA's random number library uses curandState_t to keep track of the seed value 
     we will store a random state for every thread */ 
    curandState_t* states; 

    /* allocate space on the GPU for the random states */ 
    cudaMalloc((void**) &states, N * sizeof(curandState_t)); 

    /* invoke the GPU to initialize all of the random states */ 
    init<<<N, 1>>>(time(0), states); 

    /* allocate an array of unsigned ints on the CPU and GPU */ 
    // unsigned int cpu_nums[N];//getting error in median relared to type of int 
    unsigned int* gpu_nums; 
    int cpu_nums[N]; 
    cudaMalloc((void**) &gpu_nums, N * sizeof(unsigned int)); 

    /* invoke the kernel to get some random numbers */ 
    randoms<<<N, 1>>>(states, gpu_nums); 

    /* copy the random numbers back */ 
    cudaMemcpy(cpu_nums, gpu_nums, N * sizeof(unsigned int), cudaMemcpyDeviceToHost); 

/******************************************************************************/ 

    int data[N];// int count = 0; 

    int cpunums[N],i; 
    for (i=0;i<=N;i++) 

    cpunums[i]=cpu_nums[i]; 


    cudaMalloc(&cpunums, N * sizeof(int)); 
    cudakernel<<<N/256, 256>>>(cpunums); 
    cudaMemcpy(data, cpunums, N * sizeof(int), cudaMemcpyDeviceToHost); 
    cudaFree(cpunums); 

    int sel; 
    printf("Enter an index: "); 
    scanf("%d", &sel); 
    printf("data[%d] = %f\n", sel, data[sel]); 
    } 

我試圖複製cpunums [I]從宿主數組到設備agine affter我genti從設備的隨機數字。

我試圖調用設備的功能，但我有很多errors.so我試過這種方式。

Answer 1

cudaMalloc函數代表在設備的全局內存中分配緩衝區。 你想要做什麼是主機到設備拷貝，所以你將不得不使用cudaMemcpy功能：

host ​cudaError_t cudaMemcpy (void* dst, const void* src, size_t count, cudaMemcpyKind kind)

Copies count bytes from the memory area pointed to by src to the memory area pointed to by dst, where kind specifies the direction of the copy

參見：CUDA Runtime API Documentation : cudaMemcpy

顯然，緩衝區中cudaMemcpy會寫在設備端必須先使用cudaMalloc進行分配。