BookGPU/Chapters/chapter2/ex2.cu

   1 #include <stdlib.h>
   2 #include <stdio.h>
   3 #include <string.h>
   4 #include <math.h>
   5 #include <assert.h>
   6 #include "cutil_inline.h"
   7 #include <cublas_v2.h>
   8
   9
  10 const int nbThreadsPerBloc=256;
  11
  12 __global__
  13 void addition(int size, double *d_C, double *d_A, double *d_B) {
  14         int tid = blockIdx.x * blockDim.x + threadIdx.x;
  15         if(tid<size) {
  16                 d_C[tid]=d_A[tid]+d_B[tid];
  17         }
  18 }
  19
  20 __global__
  21 void inverse(int size, double *d_x) {
  22         int tid = blockIdx.x * blockDim.x + threadIdx.x;
  23         if(tid<size) {
  24                 d_x[tid]=1./d_x[tid];
  25         }
  26 }
  27
  28
  29 int main( int argc, char** argv)
  30 {
  31
  32         if(argc!=2) {
  33                 printf("usage: ex2 nb_components\n");
  34                 exit(0);
  35         }
  36
  37         int size=atoi(argv[1]);
  38
  39         cublasStatus_t stat;
  40         cublasHandle_t handle;
  41         stat=cublasCreate(&handle);
  42
  43
  44         int i;
  45         double *h_arrayA=(double*)malloc(size*sizeof(double));
  46         double *h_arrayB=(double*)malloc(size*sizeof(double));
  47         double *h_arrayC=(double*)malloc(size*sizeof(double));
  48         double *h_arrayCgpu=(double*)malloc(size*sizeof(double));
  49         double *d_arrayA, *d_arrayB, *d_arrayC;
  50
  51
  52         cudaMalloc((void**)&d_arrayA,size*sizeof(double));
  53         cudaMalloc((void**)&d_arrayB,size*sizeof(double));
  54         cudaMalloc((void**)&d_arrayC,size*sizeof(double));
  55
  56         for(i=0;i<size;i++) {
  57                 h_arrayA[i]=i+1;
  58                 h_arrayB[i]=2*(i+1);
  59         }
  60
  61
  62         unsigned int timer_cpu = 0;
  63         cutilCheckError(cutCreateTimer(&timer_cpu));
  64   cutilCheckError(cutStartTimer(timer_cpu));
  65         double dot=0;
  66         for(i=0;i<size;i++) {
  67                 h_arrayC[i]=h_arrayA[i]+h_arrayB[i];
  68                 dot+=(1./h_arrayC[i])*(1./h_arrayA[i]);
  69         }
  70         cutilCheckError(cutStopTimer(timer_cpu));
  71         printf("CPU processing time : %f (ms) \n", cutGetTimerValue(timer_cpu));
  72         cutDeleteTimer(timer_cpu);
  73
  74
  75         unsigned int timer_gpu = 0;
  76         cutilCheckError(cutCreateTimer(&timer_gpu));
  77   cutilCheckError(cutStartTimer(timer_gpu));
  78         stat = cublasSetVector(size,sizeof(double),h_arrayA,1,d_arrayA,1);
  79         stat = cublasSetVector(size,sizeof(double),h_arrayB,1,d_arrayB,1);
  80         int nbBlocs=(size+nbThreadsPerBloc-1)/nbThreadsPerBloc;
  81
  82         addition<<<nbBlocs,nbThreadsPerBloc>>>(size,d_arrayC,d_arrayA,d_arrayB);
  83         inverse<<<nbBlocs,nbThreadsPerBloc>>>(size,d_arrayC);
  84         inverse<<<nbBlocs,nbThreadsPerBloc>>>(size,d_arrayA);
  85         double dot_gpu=0;
  86         stat = cublasDdot(handle,size,d_arrayC,1,d_arrayA,1,&dot_gpu);
  87
  88
  89         cutilCheckError(cutStopTimer(timer_gpu));
  90         printf("GPU processing time : %f (ms) \n", cutGetTimerValue(timer_gpu));
  91         cutDeleteTimer(timer_gpu);
  92         printf("cpu dot %e --- gpu dot %e\n",dot,dot_gpu);
  93
  94         cudaFree(d_arrayA);
  95         cudaFree(d_arrayB);
  96         cudaFree(d_arrayC);
  97         free(h_arrayA);
  98         free(h_arrayB);
  99         free(h_arrayC);
 100         free(h_arrayCgpu);
 101
 102         cublasDestroy(handle);
 103         return 0;
 104
 105 }