First Commit
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142
opencl_add_gpu.c
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142
opencl_add_gpu.c
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#include <stdio.h>
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#include <stdlib.h>
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#include <CL/cl.h>
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#include <sys/time.h>
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#define ARRAY_SIZE 15000576 // Tiny array
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#define LOCAL_SIZE 256 // Small work-group size
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const char *kernelSource =
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"__kernel void add(__global const float *a, __global const float *b, __global float *c) { "
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" int i = get_global_id(0); "
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" if (i < 15000576) { "
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" c[i] = a[i] + b[i]; "
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"} "
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"} ";
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double get_time() {
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struct timeval tv;
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gettimeofday(&tv, NULL);
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return tv.tv_sec + tv.tv_usec * 1e-6;
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}
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int main() {
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float *a = (float*)malloc(sizeof(float) * ARRAY_SIZE);
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float *b = (float*)malloc(sizeof(float) * ARRAY_SIZE);
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float *c = (float*)malloc(sizeof(float) * ARRAY_SIZE);
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// Initialize arrays
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for (int i = 0; i < ARRAY_SIZE; i++) {
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a[i] = i;
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b[i] = i * 2;
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}
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// Get GPU platform and device
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cl_platform_id platform;
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cl_device_id gpuDevice;
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cl_uint platformCount, deviceCount;
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clGetPlatformIDs(1, &platform, &platformCount);
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clGetDeviceIDs(platform, CL_DEVICE_TYPE_GPU, 1, &gpuDevice, &deviceCount);
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// Print GPU device info
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char deviceName[128];
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clGetDeviceInfo(gpuDevice, CL_DEVICE_NAME, 128, deviceName, NULL);
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printf("Using GPU device: %s\n", deviceName);
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// Create context and command queue
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cl_context context = clCreateContext(NULL, 1, &gpuDevice, NULL, NULL, NULL);
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cl_command_queue command_queue = clCreateCommandQueue(context, gpuDevice, 0, NULL);
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// Create buffers
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double start = get_time();
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cl_mem a_mem = clCreateBuffer(context, CL_MEM_READ_ONLY | CL_MEM_COPY_HOST_PTR, ARRAY_SIZE * sizeof(float), (void *)a, NULL);
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cl_mem b_mem = clCreateBuffer(context, CL_MEM_READ_ONLY | CL_MEM_COPY_HOST_PTR, ARRAY_SIZE * sizeof(float), (void *)b, NULL);
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cl_mem c_mem = clCreateBuffer(context, CL_MEM_WRITE_ONLY, ARRAY_SIZE * sizeof(float), NULL, NULL);
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double buffer_create_time = get_time() - start;
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// Time data transfer to device (not needed with CL_MEM_COPY_HOST_PTR)
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double transfer_to_device_time = 0.0;
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// Create and build program
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start = get_time();
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cl_program program = clCreateProgramWithSource(context, 1, &kernelSource, NULL, NULL);
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cl_int ret = clBuildProgram(program, 1, &gpuDevice, NULL, NULL, NULL);
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if (ret != CL_SUCCESS) {
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size_t log_size;
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clGetProgramBuildInfo(program, gpuDevice, CL_PROGRAM_BUILD_LOG, 0, NULL, &log_size);
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char *log = (char *)malloc(log_size);
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clGetProgramBuildInfo(program, gpuDevice, CL_PROGRAM_BUILD_LOG, log_size, log, NULL);
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printf("Kernel compilation error:\n%s\n", log);
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free(log);
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return 1;
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}
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double program_build_time = get_time() - start;
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// Create kernel
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start = get_time();
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cl_kernel kernel = clCreateKernel(program, "add", NULL);
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if (!kernel) {
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printf("Error creating kernel\n");
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return 1;
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}
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double kernel_create_time = get_time() - start;
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// Set kernel arguments
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start = get_time();
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ret = clSetKernelArg(kernel, 0, sizeof(cl_mem), (void *)&a_mem);
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ret |= clSetKernelArg(kernel, 1, sizeof(cl_mem), (void *)&b_mem);
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ret |= clSetKernelArg(kernel, 2, sizeof(cl_mem), (void *)&c_mem);
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if (ret != CL_SUCCESS) {
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printf("Error setting kernel arguments: %d\n", ret);
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return 1;
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}
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double kernel_arg_time = get_time() - start;
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// Execute kernel
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start = get_time();
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size_t global_size = ARRAY_SIZE;
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size_t local_size = LOCAL_SIZE;
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ret = clEnqueueNDRangeKernel(command_queue, kernel, 1, NULL, &global_size, &local_size, 0, NULL, NULL);
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if (ret != CL_SUCCESS) {
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printf("Error executing kernel: %d\n", ret);
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return 1;
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}
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clFinish(command_queue);
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double kernel_exec_time = get_time() - start;
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// Read result back
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start = get_time();
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ret = clEnqueueReadBuffer(command_queue, c_mem, CL_TRUE, 0, ARRAY_SIZE * sizeof(float), c, 0, NULL, NULL);
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if (ret != CL_SUCCESS) {
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printf("Error reading from memory buffer: %d\n", ret);
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return 1;
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}
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double transfer_to_host_time = get_time() - start;
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// Print timing results
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printf("Buffer creation time: %.6f ms\n", buffer_create_time * 1000);
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printf("Program build time: %.6f ms\n", program_build_time * 1000);
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printf("Kernel creation time: %.6f ms\n", kernel_create_time * 1000);
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printf("Kernel argument setup time: %.6f ms\n", kernel_arg_time * 1000);
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printf("Kernel execution time: %.6f ms\n", kernel_exec_time * 1000);
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printf("Data transfer to host: %.6f ms\n", transfer_to_host_time * 1000);
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printf("Total time: %.6f ms\n",
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(buffer_create_time + program_build_time + kernel_create_time +
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kernel_arg_time + kernel_exec_time + transfer_to_host_time) * 1000);
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// Print the result
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for (int i = 0; i < 8; i++) {
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printf("c[%d] = %f\n", i, c[i]);
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}
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// Cleanup
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clReleaseMemObject(a_mem);
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clReleaseMemObject(b_mem);
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clReleaseMemObject(c_mem);
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clReleaseKernel(kernel);
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clReleaseProgram(program);
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clReleaseCommandQueue(command_queue);
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clReleaseContext(context);
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return 0;
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}
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