__kernel void vector_add(__global float *A, __global float *B, __global float *C) {
// Get the index of the current element
int i = get_global_id(0);
// Do the operation
C[i] = sqrt(A[i]) * sqrt(B[i]);
}
#include <cstdlib>
#include <iostream>
#include <chrono>
#include <math.h>
#ifdef __APPLE__
#include "OpenCL/opencl.h"
#else
#include "CL/cl.h"
#endif
#define MAX_SOURCE_SIZE (0x100000)
using namespace std;
void cpu(const int size)
{
// Create the two input vectors
int i;
float *A = (float*)malloc(sizeof(int)*size);
float *B = (float*)malloc(sizeof(int)*size);
for(i = 0; i < size; i++) {
A[i] = i;
B[i] = size - i;
}
// Calculate C on CPU
float *C = (float*)malloc(sizeof(int)*size);
for(i = 0; i < size; i++) {
C[i] = sqrt(A[i]) * sqrt(B[i]);
}
// Display the result to the screen
for(i = 0; i < size; i++) {
//printf("sqrt(%f) * sqrt(%f) = %f\n", A[i], B[i], C[i]);
}
free(A);
free(B);
free(C);
}
void gpu(const int size)
{
// Create the two input vectors
int i;
float *A = (float*)malloc(sizeof(int)*size);
float *B = (float*)malloc(sizeof(int)*size);
for(i = 0; i < size; i++) {
A[i] = i;
B[i] = size - i;
}
// Load the kernel source code into the array source_str
FILE *fp;
char *source_str;
size_t source_size;
fp = fopen("vector_add_kernel.cl", "r");
if (!fp) {
fprintf(stderr, "Failed to load kernel.\n");
exit(1);
}
source_str = (char*)malloc(MAX_SOURCE_SIZE);
source_size = fread( source_str, 1, MAX_SOURCE_SIZE, fp);
fclose( fp );
// Get platform and device information
cl_platform_id platform_id = NULL;
cl_device_id device_id = NULL;
cl_uint ret_num_devices;
cl_uint ret_num_platforms;
cl_int ret = clGetPlatformIDs(1, &platform_id, &ret_num_platforms);
ret = clGetDeviceIDs( platform_id, CL_DEVICE_TYPE_ALL, 1,
&device_id, &ret_num_devices);
// Create an OpenCL context
cl_context context = clCreateContext( NULL, 1, &device_id, NULL, NULL, &ret);
// Create a command queue
cl_command_queue command_queue = clCreateCommandQueue(context, device_id, 0, &ret);
// Create memory buffers on the device for each vector
cl_mem a_mem_obj = clCreateBuffer(context, CL_MEM_READ_ONLY,
size * sizeof(int), NULL, &ret);
cl_mem b_mem_obj = clCreateBuffer(context, CL_MEM_READ_ONLY,
size * sizeof(int), NULL, &ret);
cl_mem c_mem_obj = clCreateBuffer(context, CL_MEM_WRITE_ONLY,
size * sizeof(int), NULL, &ret);
// Copy the lists A and B to their respective memory buffers
ret = clEnqueueWriteBuffer(command_queue, a_mem_obj, CL_TRUE, 0,
size * sizeof(int), A, 0, NULL, NULL);
ret = clEnqueueWriteBuffer(command_queue, b_mem_obj, CL_TRUE, 0,
size * sizeof(int), B, 0, NULL, NULL);
// Create a program from the kernel source
cl_program program = clCreateProgramWithSource(context, 1,
(const char **)&source_str, (const size_t *)&source_size, &ret);
// Build the program
ret = clBuildProgram(program, 1, &device_id, NULL, NULL, NULL);
// Create the OpenCL kernel
cl_kernel kernel = clCreateKernel(program, "vector_add", &ret);
// Set the arguments of the kernel
ret = clSetKernelArg(kernel, 0, sizeof(cl_mem), (void *)&a_mem_obj);
ret = clSetKernelArg(kernel, 1, sizeof(cl_mem), (void *)&b_mem_obj);
ret = clSetKernelArg(kernel, 2, sizeof(cl_mem), (void *)&c_mem_obj);
// Execute the OpenCL kernel on the list
size_t global_item_size = size; // Process the entire lists
size_t local_item_size = 64; // Process in groups of 64
ret = clEnqueueNDRangeKernel(command_queue, kernel, 1, NULL,
&global_item_size, &local_item_size, 0, NULL, NULL);
// Read the memory buffer C on the device to the local variable C
float *C = (float*)malloc(sizeof(int)*size);
ret = clEnqueueReadBuffer(command_queue, c_mem_obj, CL_TRUE, 0,
size * sizeof(int), C, 0, NULL, NULL);
// Display the result to the screen
for(i = 0; i < size; i++) {
//printf("sqrt(%f) * sqrt(%f) = %f\n", A[i], B[i], C[i]);
}
// Clean up
ret = clFlush(command_queue);
ret = clFinish(command_queue);
ret = clReleaseKernel(kernel);
ret = clReleaseProgram(program);
ret = clReleaseMemObject(a_mem_obj);
ret = clReleaseMemObject(b_mem_obj);
ret = clReleaseMemObject(c_mem_obj);
ret = clReleaseCommandQueue(command_queue);
ret = clReleaseContext(context);
free(A);
free(B);
free(C);
}
int main(void)
{
typedef std::chrono::high_resolution_clock Time;
typedef std::chrono::milliseconds ms;
typedef std::chrono::duration<float> fsec;
int size = 1024 * 1024 * 1024;
auto cpu_start = Time::now();
cpu(size);
auto cpu_finish = Time::now();
ms cpu_diff = std::chrono::duration_cast<ms>(cpu_finish - cpu_start);
auto gpu_start = Time::now();
gpu(size);
auto gpu_finish = Time::now();
ms gpu_diff = std::chrono::duration_cast<ms>(gpu_finish - gpu_start);
printf("CPU: %ld ms, GPU: %ld ms\n", cpu_diff, gpu_diff);
return 0;
}
I can't tell what's wrong as I'm new to parallel programming, so I was hoping you could take a look.