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CUDA5.5入门1. host和gpu之间的通信
《cuda programming 》 Shane Cook 第5章 第一节
cpu和gpu有各自独立的内存空间,两者不可以直接访问。
每个线程的执行代码是一样的,数据不同。
Thread---->Warp------>Block------>Grid
入门代码是并行加法: 1.cpu端的数组
2.开辟gpu的buffer : cudaMalloc((void**)&dev_a,arraySize*sizeof(int));
3.把host数据传入buffer : cudaMemcpy(dev_a,a,arraySize*sizeof(int),cudaMemcpyHostToDevice);
4.在Kernel中每个Thread进行相应的计算: addKernelArray<<<1,arraySize>>>(dev_c,dev_b,dev_a);
5.把devcudaMemcpy(c,dev_c,arraySize*sizeof(int),cudaMemcpyDeviceToHost);
结果:
2 3 4 5 6
ThreadID:0 Block:0 warp:0 eachBT:0 wrapSize32
ThreadID:1 Block:0 warp:0 eachBT:1 wrapSize32
ThreadID:2 Block:0 warp:0 eachBT:2 wrapSize32
ThreadID:3 Block:0 warp:0 eachBT:3 wrapSize32
ThreadID:4 Block:0 warp:0 eachBT:4 wrapSize32
ThreadID:5 Block:0 warp:0 eachBT:5 wrapSize32
ThreadID:6 Block:0 warp:0 eachBT:6 wrapSize32
ThreadID:7 Block:0 warp:0 eachBT:7 wrapSize32
ThreadID:8 Block:0 warp:0 eachBT:8 wrapSize32
ThreadID:9 Block:0 warp:0 eachBT:9 wrapSize32
ThreadID:10 Block:0 warp:0 eachBT:10 wrapSize32
ThreadID:11 Block:0 warp:0 eachBT:11 wrapSize32
ThreadID:12 Block:0 warp:0 eachBT:12 wrapSize32
ThreadID:13 Block:0 warp:0 eachBT:13 wrapSize32
ThreadID:14 Block:0 warp:0 eachBT:14 wrapSize32
ThreadID:15 Block:0 warp:0 eachBT:15 wrapSize32
ThreadID:16 Block:0 warp:0 eachBT:16 wrapSize32
ThreadID:17 Block:0 warp:0 eachBT:17 wrapSize32
ThreadID:18 Block:0 warp:0 eachBT:18 wrapSize32
ThreadID:19 Block:0 warp:0 eachBT:19 wrapSize32
ThreadID:20 Block:0 warp:0 eachBT:20 wrapSize32
ThreadID:21 Block:0 warp:0 eachBT:21 wrapSize32
ThreadID:22 Block:0 warp:0 eachBT:22 wrapSize32
ThreadID:23 Block:0 warp:0 eachBT:23 wrapSize32
ThreadID:24 Block:0 warp:0 eachBT:24 wrapSize32
ThreadID:25 Block:0 warp:0 eachBT:25 wrapSize32
ThreadID:26 Block:0 warp:0 eachBT:26 wrapSize32
ThreadID:27 Block:0 warp:0 eachBT:27 wrapSize32
ThreadID:28 Block:0 warp:0 eachBT:28 wrapSize32
ThreadID:29 Block:0 warp:0 eachBT:29 wrapSize32
ThreadID:30 Block:0 warp:0 eachBT:30 wrapSize32
ThreadID:31 Block:0 warp:0 eachBT:31 wrapSize32
ThreadID:32 Block:0 warp:1 eachBT:32 wrapSize32
ThreadID:33 Block:0 warp:1 eachBT:33 wrapSize32
ThreadID:34 Block:0 warp:1 eachBT:34 wrapSize32
ThreadID:35 Block:0 warp:1 eachBT:35 wrapSize32
ThreadID:36 Block:0 warp:1 eachBT:36 wrapSize32
ThreadID:37 Block:0 warp:1 eachBT:37 wrapSize32
ThreadID:38 Block:0 warp:1 eachBT:38 wrapSize32
ThreadID:39 Block:0 warp:1 eachBT:39 wrapSize32
ThreadID:40 Block:0 warp:1 eachBT:40 wrapSize32
ThreadID:41 Block:0 warp:1 eachBT:41 wrapSize32........................................
................................................
疑问:现在还没想通:
当test_ThreadNums_BlockNums_WarpNums<<<2,64>>>里参数修改成《2,128》时,输出结果不理解。
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 | #include "cuda_runtime.h" #include "device_launch_parameters.h" #include <stdio.h> #include<iostream> using namespace std; __global__ void addKernelArray( int *c, int * a, int *b) { int i = threadIdx.x; c[i] = a[i]+b[i]; } //calculate NO. __global__ void test_ThreadNums_BlockNums_WarpNums( int * threadNum, int *blockNums, int *WarpNums, int *threadIndex, int *gpu_warpSize) { int i = threadIdx.x + (blockIdx.x*blockDim.x); //thread ID threadNum[i] = threadIdx.x; //each block‘s thread NO. blockNums[i] = blockIdx.x; WarpNums[i] = threadIdx.x/warpSize; threadIndex[i] = i; //thread ID gpu_warpSize[i] = warpSize; } int main() { //BEGIN calculate two arrays add const int arraySize = 5; int a[arraySize] = {1,2,3,4,5}; int b[arraySize] = {1,1,1,1,1}; int c[arraySize] = {0}; int *dev_a=0; int *dev_b=0; int *dev_c=0; //allocate gpu buffer cudaMalloc(( void **)&dev_a,arraySize* sizeof ( int )); cudaMalloc(( void **)&dev_b,arraySize* sizeof ( int )); cudaMalloc(( void **)&dev_c,arraySize* sizeof ( int )); //copy host memory to gpu buffer cudaMemcpy(dev_a,a,arraySize* sizeof ( int ),cudaMemcpyHostToDevice); cudaMemcpy(dev_b,b,arraySize* sizeof ( int ),cudaMemcpyHostToDevice); cudaMemcpy(dev_c,c,arraySize* sizeof ( int ),cudaMemcpyHostToDevice); addKernelArray<<<1,arraySize>>>(dev_c,dev_b,dev_a); //copy gpu buffer to host memory cudaMemcpy(c,dev_c,arraySize* sizeof ( int ),cudaMemcpyDeviceToHost); for ( int i=0;i<arraySize;i++) { std::cout<<c[i]<< " " ; } std::cout<<std::endl; //END calculate two arrays add //BEGIN capture thread,block,warp num const int cudaBlockNums =2; const int cudaAllThreadNums =128; int cpu_ThreadId[cudaAllThreadNums] = {0}; int cpu_BlockNums[cudaAllThreadNums] = {0}; int cpu_WarpNums[cudaAllThreadNums]={0}; int cpu_eachBlockThreadNum[cudaAllThreadNums] = {0}; int cpu_warpSize[cudaAllThreadNums] = {0}; int *gpu_threadId=0; int *gpu_block=0; int *gpu_warp=0; int *gpu_eachBlockThreadNums=0; int *gpu_warpSize=0; //申请gpu buffer cudaMalloc(( void **)&gpu_threadId,cudaAllThreadNums* sizeof ( int )); cudaMalloc(( void **)&gpu_block,cudaAllThreadNums* sizeof ( int )); cudaMalloc(( void **)&gpu_warp,cudaAllThreadNums* sizeof ( int )); cudaMalloc(( void **)&gpu_eachBlockThreadNums,cudaAllThreadNums* sizeof ( int )); cudaMalloc(( void **)&gpu_warpSize,cudaAllThreadNums* sizeof ( int )); //记录数据 test_ThreadNums_BlockNums_WarpNums<<<2,64>>>(gpu_eachBlockThreadNums,gpu_block,gpu_warp,gpu_threadId,gpu_warpSize); //拷贝到cpu里 cudaMemcpy(cpu_ThreadId,gpu_threadId,cudaAllThreadNums* sizeof ( int ),cudaMemcpyDeviceToHost); cudaMemcpy(cpu_BlockNums,gpu_block,cudaAllThreadNums* sizeof ( int ),cudaMemcpyDeviceToHost); cudaMemcpy(cpu_WarpNums,gpu_warp,cudaAllThreadNums* sizeof ( int ),cudaMemcpyDeviceToHost); cudaMemcpy(cpu_eachBlockThreadNum,gpu_eachBlockThreadNums,cudaAllThreadNums* sizeof ( int ),cudaMemcpyDeviceToHost); cudaMemcpy(cpu_warpSize,gpu_warpSize,cudaAllThreadNums* sizeof ( int ),cudaMemcpyDeviceToHost); for ( int i=0;i<cudaAllThreadNums;i++) { std::cout<< "ThreadID:" <<cpu_ThreadId[i]<< " Block:" <<cpu_BlockNums[i]<< " warp:" <<cpu_WarpNums[i]<< " eachBT:" <<cpu_eachBlockThreadNum[i]<< " wrapSize" <<cpu_warpSize[i]<<endl; } //END capture thread,block,warp num return 0; } |