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→Assignment 2
=== Assignment 2 ===
<pre>
#include <iostream>
#include <cstdlib>
#include <cuda_runtime.h>
using namespace std;
/* Initializes the matrix to any random number between 0 and 1 */
void initializeMatrix(float* a, int size){
float f = 1.0 / RAND_MAX;
for(int i = 0; i < size * size; i++)
a[i] = rand() * f;
}
/* Displays the matrix */
void matrixDisplay(char matrix, float* a, int size){
int i = 0;
cout << matrix <<" is: " << endl;
while(i < size*size){
for(int j = 0; j < size; j++, i++)
cout << a[i] << " ";
cout << endl;
}
}
/* Creates the Summed area table */
__global__ void SummedAreaTable(float* A, float* B, int size){
int idx = blockIdx.x * blockDim.x + threadIdx.x;
float sum = 0;
int rest;
if(idx < (size*size)){
if(idx < size)
rest = idx;
else{
rest = idx - size;
while(rest >= size)
rest = rest - size;
}
for(int i = (size*size) - size + rest; i >= idx - rest; i -= size)
for(int j = i, k = rest; k >= 0; j--, k--)
sum += A[j];
B[idx] = sum;
}
}
int main(int argc, char* argv[]){
if(argc == 2){ // only one argument (program name + one argument) allowed
int size = atoi(argv[1]);
int tSize = size * size;
int d;
int nThreads;
int mThreads;
int Blocks;
int Threads;
float *a = new float[tSize];
float *A;
float *b = new float[tSize];
float *B;
cudaError_t error; // error handler
/* Gets the maximum number of threads and blocks */
cudaDeviceProp prop;
cudaGetDevice(&d);
cudaGetDeviceProperties(&prop, d);
nThreads = prop.maxThreadsDim[0];
mThreads = nThreads * prop.maxGridSize[0];
/* Checks if the size of the matrix is less than the maximum number of threads */
if((tSize) < nThreads){
Blocks = 1;
Threads = tSize;
}
/* Checks if the size of the matrix is greater than the maximum number of threads */
else if((tSize) > nThreads){
Blocks = (tSize + nThreads - 1) / nThreads;
Threads = nThreads;
}
/* Checks if the size of the matrix is less than the maximum number of threads multipled by the maximum number of blocks */
else if((tSize) > mThreads){
tSize = mThreads;
Blocks = (tSize + nThreads - 1) / nThreads;
Threads = nThreads;
}
dim3 dGrid(Blocks, Blocks, 1); // sets the grids
dim3 dBlock(Threads, Threads, 1); // sets the blocks
initializeMatrix(a,size); // initializes the matrix a
error = cudaMalloc((void**)&A, tSize * sizeof(float)); // allocates memory on the device for matrix A;
if (error != cudaSuccess) {
cout << cudaGetErrorString(error) << endl;
}
error = cudaMalloc((void**)&B, tSize * sizeof(float)); // allocates memory on the device for matrix B;
if (error != cudaSuccess) {
cout << cudaGetErrorString(error) << endl;
}
error = cudaMemcpy(A, a, tSize * sizeof(float), cudaMemcpyHostToDevice); // copies the host matrix a into the device matrix A
if (error != cudaSuccess) {
cout << cudaGetErrorString(error) << endl;
}
/* Performs the SAT on the device on A and stores it on B */
SummedAreaTable<<<Blocks,Threads>>>(A,B,size); // Does the SAT on a and stores it on b
cudaDeviceSynchronize(); // synchronizes the host and the device
error = cudaGetLastError();
if (error != cudaSuccess) {
cout << cudaGetErrorString(error) << endl;
cudaFree(a);
cudaFree(b);
delete [] a;
delete [] b;
return 3;
}
/* copies device matrix B into host matrix b */
error = cudaMemcpy(b, B, tSize * sizeof(float), cudaMemcpyDeviceToHost);
if (error != cudaSuccess) {
cout << cudaGetErrorString(error) << endl;
}
//matrixDisplay('a', a, size); //uncomment/comment to display/not display the matrix a
//matrixDisplay('b', b, size); //uncomment/comment to display/not display the matrix b
/* deallocates space in both host memory and device memory */
cudaFree(A);
cudaFree(B);
delete [] a;
delete [] b;
cudaDeviceReset();
cout << "Finished" << endl;
return 0;
}
else if(argc < 2){
cout << "Please provide a size" << endl; // when no arguments are supplied
return 0;
}
else{
cout << "Only one size is allowed" << endl; // when more than one argument(the program name + one or more arguments) is supplied
return 0;
}
}
Size
A1 (CPU)
A2 (GPU)
100
0.03
0.0034
200
0.61
0.0445
300
3.08
0.2124
400
9.66
0.6549
500
24.17
1.58
600
54.4
3.268
700
113.17
5.976
</pre>
