了解了深度学习的崛起，引起了目前OpenCL的需求，大致了解一下。
相关内容：http://blog.csdn.net/leonwei/article/details/8880012
本身OpenCL可以用C／C++编程，所以，我们底层人员又可以浪了。
// // File: hello.c // // Abstract: A simple "Hello World" compute example showing basic usage of OpenCL which // calculates the mathematical square (X[i] = pow(X[i],2)) for a buffer of // floating point values. // // // Version: <1.0> // // Disclaimer: IMPORTANT: This Apple software is supplied to you by Apple Inc. ("Apple") // in consideration of your agreement to the following terms, and your use, // installation, modification or redistribution of this Apple software // constitutes acceptance of these terms. If you do not agree with these // terms, please do not use, install, modify or redistribute this Apple // software. // // In consideration of your agreement to abide by the following terms, and // subject to these terms, Apple grants you a personal, non - exclusive // license, under Apple's copyrights in this original Apple software ( the // "Apple Software" ), to use, reproduce, modify and redistribute the Apple // Software, with or without modifications, in source and / or binary forms; // provided that if you redistribute the Apple Software in its entirety and // without modifications, you must retain this notice and the following text // and disclaimers in all such redistributions of the Apple Software. Neither // the name, trademarks, service marks or logos of Apple Inc. may be used to // endorse or promote products derived from the Apple Software without specific // prior written permission from Apple. Except as expressly stated in this // notice, no other rights or licenses, express or implied, are granted by // Apple herein, including but not limited to any patent rights that may be // infringed by your derivative works or by other works in which the Apple // Software may be incorporated. // // The Apple Software is provided by Apple on an "AS IS" basis. APPLE MAKES NO // WARRANTIES, EXPRESS OR IMPLIED, INCLUDING WITHOUT LIMITATION THE IMPLIED // WARRANTIES OF NON - INFRINGEMENT, MERCHANTABILITY AND FITNESS FOR A // PARTICULAR PURPOSE, REGARDING THE APPLE SOFTWARE OR ITS USE AND OPERATION // ALONE OR IN COMBINATION WITH YOUR PRODUCTS. // // IN NO EVENT SHALL APPLE BE LIABLE FOR ANY SPECIAL, INDIRECT, INCIDENTAL OR // CONSEQUENTIAL DAMAGES ( INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF // SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS // INTERRUPTION ) ARISING IN ANY WAY OUT OF THE USE, REPRODUCTION, MODIFICATION // AND / OR DISTRIBUTION OF THE APPLE SOFTWARE, HOWEVER CAUSED AND WHETHER // UNDER THEORY OF CONTRACT, TORT ( INCLUDING NEGLIGENCE ), STRICT LIABILITY OR // OTHERWISE, EVEN IF APPLE HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. // // Copyright ( C ) 2008 Apple Inc. All Rights Reserved. // //////////////////////////////////////////////////////////////////////////////// #include <fcntl.h> #include <stdio.h> #include <stdlib.h> #include <string.h> #include <math.h> #include <unistd.h> #include <sys/types.h> #include <sys/stat.h> #include <OpenCL/opencl.h> //////////////////////////////////////////////////////////////////////////////// // Use a static data size for simplicity // #define DATA_SIZE (1024) //////////////////////////////////////////////////////////////////////////////// // Simple compute kernel which computes the square of an input array // const char *KernelSource = " " "__kernel void square( " " __global float* input, " " __global float* output, " " const unsigned int count) " "{ " " int i = get_global_id(0); " " if(i < count) " " output[i] = input[i] * input[i]; " "} " " "; //////////////////////////////////////////////////////////////////////////////// int main(int argc, char** argv) { int err; // error code returned from api calls float data[DATA_SIZE]; // original data set given to device float results[DATA_SIZE]; // results returned from device unsigned int correct; // number of correct results returned size_t global; // global domain size for our calculation size_t local; // local domain size for our calculation cl_device_id device_id; // compute device id cl_context context; // compute context cl_command_queue commands; // compute command queue cl_program program; // compute program cl_kernel kernel; // compute kernel cl_mem input; // device memory used for the input array cl_mem output; // device memory used for the output array // Fill our data set with random float values // int i = 0; unsigned int count = DATA_SIZE; for(i = 0; i < count; i++) data[i] = rand() / (float)RAND_MAX; // Connect to a compute device // int gpu = 1; err = clGetDeviceIDs(NULL, gpu ? CL_DEVICE_TYPE_GPU : CL_DEVICE_TYPE_CPU, 1, &device_id, NULL); if (err != CL_SUCCESS) { printf("Error: Failed to create a device group! "); return EXIT_FAILURE; } // Create a compute context // context = clCreateContext(0, 1, &device_id, NULL, NULL, &err); if (!context) { printf("Error: Failed to create a compute context! "); return EXIT_FAILURE; } // Create a command commands // commands = clCreateCommandQueue(context, device_id, 0, &err); if (!commands) { printf("Error: Failed to create a command commands! "); return EXIT_FAILURE; } // Create the compute program from the source buffer // program = clCreateProgramWithSource(context, 1, (const char **) & KernelSource, NULL, &err); if (!program) { printf("Error: Failed to create compute program! "); return EXIT_FAILURE; } // Build the program executable // err = clBuildProgram(program, 0, NULL, NULL, NULL, NULL); if (err != CL_SUCCESS) { size_t len; char buffer[2048]; printf("Error: Failed to build program executable! "); clGetProgramBuildInfo(program, device_id, CL_PROGRAM_BUILD_LOG, sizeof(buffer), buffer, &len); printf("%s ", buffer); exit(1); } // Create the compute kernel in the program we wish to run // kernel = clCreateKernel(program, "square", &err); if (!kernel || err != CL_SUCCESS) { printf("Error: Failed to create compute kernel! "); exit(1); } // Create the input and output arrays in device memory for our calculation // input = clCreateBuffer(context, CL_MEM_READ_ONLY, sizeof(float) * count, NULL, NULL); output = clCreateBuffer(context, CL_MEM_WRITE_ONLY, sizeof(float) * count, NULL, NULL); if (!input || !output) { printf("Error: Failed to allocate device memory! "); exit(1); } // Write our data set into the input array in device memory // err = clEnqueueWriteBuffer(commands, input, CL_TRUE, 0, sizeof(float) * count, data, 0, NULL, NULL); if (err != CL_SUCCESS) { printf("Error: Failed to write to source array! "); exit(1); } // Set the arguments to our compute kernel // err = 0; err = clSetKernelArg(kernel, 0, sizeof(cl_mem), &input); err |= clSetKernelArg(kernel, 1, sizeof(cl_mem), &output); err |= clSetKernelArg(kernel, 2, sizeof(unsigned int), &count); if (err != CL_SUCCESS) { printf("Error: Failed to set kernel arguments! %d ", err); exit(1); } // Get the maximum work group size for executing the kernel on the device // err = clGetKernelWorkGroupInfo(kernel, device_id, CL_KERNEL_WORK_GROUP_SIZE, sizeof(local), &local, NULL); if (err != CL_SUCCESS) { printf("Error: Failed to retrieve kernel work group info! %d ", err); exit(1); } // Execute the kernel over the entire range of our 1d input data set // using the maximum number of work group items for this device // global = count; err = clEnqueueNDRangeKernel(commands, kernel, 1, NULL, &global, &local, 0, NULL, NULL); if (err) { printf("Error: Failed to execute kernel! "); return EXIT_FAILURE; } // Wait for the command commands to get serviced before reading back results // clFinish(commands); // Read back the results from the device to verify the output // err = clEnqueueReadBuffer( commands, output, CL_TRUE, 0, sizeof(float) * count, results, 0, NULL, NULL ); if (err != CL_SUCCESS) { printf("Error: Failed to read output array! %d ", err); exit(1); } // Validate our results // correct = 0; for(i = 0; i < count; i++) { if(results[i] == data[i] * data[i]) correct++; } // Print a brief summary detailing the results // printf("Computed '%d/%d' correct values! ", correct, count); // Shutdown and cleanup // clReleaseMemObject(input); clReleaseMemObject(output); clReleaseProgram(program); clReleaseKernel(kernel); clReleaseCommandQueue(commands); clReleaseContext(context); return 0; }
运行结果：
Computed '1024/1024' correct values!
Program ended with exit code: 0