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/*
* A cuda implementation of the Matrix-Vector multiplication
*
* Author: Petros Anastasiadis(panastas@cslab.ece.ntua.gr)
*
* The device code for the GPU implemntations can be found in the 'dmv_gpu.cu' file
*
* For more info about coalesced memmory access and shmem, see https://cvw.cac.cornell.edu/gpu/coalesced
*/
#include <errno.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <cuda_runtime.h>
#include <cublas_v2.h>
#include <cusparse_v2.h>
#include "dmv_gpu.h"
/* Need to include External_Functions for these */
#include "matrix_op.h"
#include "util.h"
#include "input.h"
#include "gpu_util.h"
#define block_size 256 /* Number of GPU threads per block. Modifying this value might lead to performance issues */
int main(int argc, char **argv)
{
/* Initializations */
int i, j, n, m;
if (argc < 3) error("Usage: ./Program N M");
else if ( argc == 3) { /*./Program N M */
n = atoi(argv[1]);
m = atoi(argv[2]);
}
else error("Too many Arguments");
int grid_size = (n-1)/block_size + 1;
size_t shmem_size = 0;
dim3 gpu_block(block_size, 1);
dim3 gpu_grid(grid_size, 1);
/* Allocate space */
double *x = (double *) malloc(m * sizeof(*x));
double *y = (double *) malloc(n * sizeof(*y));
double *M = (double *) malloc(n * m * sizeof(*M));
if( !y || !x || !M ) error("memory allocation failed");
/* Initialize matrices */
ser_matrix_init_rand(M, n, m, 1.0); /* Normal matrices generated randomly */
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/* Initialize vectors */
vec_init_rand(x, m, 1.0);
vec_init(y, n, 0.0);
/* Initialize cuda variables */
int device_num=0;
cudaGetDeviceCount(&device_num);
if (!device_num) printf("No available Cuda Devices");
else {
cudaSetDevice(0);
printf("Single GPU CUDA Version(N=%d, M=%d): ", n, m);
double *A, * y, *x_c;
/* Initialize Unified memmory visible and accesible from both CPU and GPU */
cudaMallocManaged(&A, m*n * sizeof(double));
cudaMallocManaged(&y, n * sizeof(double));
cudaMallocManaged(&x_c, m * sizeof(double));
cudaDeviceSynchronize();
cudaCheckErrors("Unified Alloc failed");
if ( !A || !y || !x_c) error("unified alloc failed");
for (i = 0; i < m; i++) x_c[i] = x[i];
/* First naive kernel */
for ( i = 0; i < n*m; i++) A[i] = M[i] ;
timer=csecond();
for (j = 0; j < NR_ITER; ++j) {
dmv_gpu_naive<<<gpu_grid,gpu_block,shmem_size>>>(A, x_c, y, m);
cudaDeviceSynchronize();
}
timer = csecond() - timer;
cudaCheckErrors("naive kernel failed");
report_results(timer);
/* Second kernel, using coalesced memmory accesses in the GPU by transposing the matrix. */
printf("Single GPU CUDA Coalesced Version(N=%d, M=%d): ", n, m);
matrix_col_major(M, A, n, m); /* We transpose the matrix to better match the GPU coalesced memmory access logic */
timer=csecond();
for (j = 0; j < NR_ITER; ++j) {
dmv_gpu_coalesced<<<gpu_grid,gpu_block,shmem_size>>>(A, x_c, y, m);
cudaDeviceSynchronize();
}
timer = csecond() - timer;
cudaCheckErrors("coalesced kernel failed");
report_results(timer);
/* Third and final kernel further improves memmory access speed by using block exclusive shmem */
printf("Single GPU CUDA shmem Version(N=%d, M=%d): ", n, m);
shmem_size= block_size*sizeof(float);
timer=csecond();
for (j = 0; j < NR_ITER; ++j) {
dmv_gpu_shmem<<<gpu_grid,gpu_block,shmem_size>>>(A, x_c, y, m);
cudaDeviceSynchronize();
}
timer = csecond() - timer;
cudaCheckErrors("shmem kernel failed");
#ifdef _DEBUG_
/* Output y vector to a file for debugging */
FILE * fp;
char filename[] = "CUDA.debug" ; /* Common directory for all implementations, change if needed */
if(( fp = fopen( filename, "w")) == NULL) error("Output file creation failed\n");
for (i = 0; i < n; ++i) fprintf(fp, "%lf ", y[i]) ;
fclose(fp) ;
#endif
report_results(timer);
}
return 0;
}