The following code snippet measures kernel execution using the OpenCL™ profiling events (error handling is omitted):
g_cmd_queue = clCreateCommandQueue(…CL_QUEUE_PROFILING_ENABLE, NULL); clEnqueueNDRangeKernel(g_cmd_queue,…, &perf_event); clWaitForEvents(1, &perf_event); cl_ulong start = 0, end = 0; clGetEventProfilingInfo(perf_event, CL_PROFILING_COMMAND_START, sizeof(cl_ulong), &start, NULL); clGetEventProfilingInfo(perf_event, CL_PROFILING_COMMAND_END, sizeof(cl_ulong), &end, NULL); //END-START gives you hints on kind of “pure HW execution time” //the resolution of the events is 1e-09 sec g_NDRangePureExecTimeMs = (cl_double)(end - start)*(cl_double)(1e-06);
Also consider the following:
CL_QUEUE_PROFILING_ENABLE
property in creation time.clFinish()
or clWaitForEvents
because device time counters for the
profiled command are associated with the specified event.Using the profiling operations, you can profile operations on both memory objects and kernels. Refer to section 5.12 of the OpenCL 1.2 Specification for the detailed description of profiling events.
NOTE: The host-side wall-clock time might return different results. For the CPU device, the difference is typically minor.