Why are opencl enqueue commands so time consuming? - performance

Question

I am trying to do live audio processing using the Intel HD Graphics GPU. I theory they should be perfect for this. But I am surprised at cost of the enqueuing commands. This looks to be a prohibiting factor, and by far the most time-consuming step.
In short calling the enqueueXXXXX commands take a long time. Actually doing the data copying and executing the kernel is sufficiently fast. Is this just an inherent problem with the OpenCL implementation, or am I doing something wrong?
Data copying + kernel execution takes about 10us
Calling the enqueue commands takes about 300us - 500us
The code is available at https://github.com/tblum/opencl_enqueue/blob/master/main.cpp
for (int i = 0; i < 10; ++i) {
cl::Event copyToEvent;
cl::Event copyFromEvent;
cl::Event kernelEvent;
auto t1 = Clock::now();
commandQueue.enqueueWriteBuffer(clIn, CL_FALSE, 0, 10 * 48 * sizeof(float), frameBufferIn, nullptr, &copyToEvent);
OCLdownMix.setArg(0,clIn);
OCLdownMix.setArg(1,clOut);
OCLdownMix.setArg(2,(unsigned int)480);
commandQueue.enqueueNDRangeKernel(OCLdownMix, cl::NullRange, cl::NDRange(480), cl::NDRange(48), nullptr, &kernelEvent);
commandQueue.enqueueReadBuffer(clOut, CL_FALSE, 0, 10 * 48 * sizeof(float), clResult, nullptr, &copyFromEvent);
auto t2 = Clock::now();
commandQueue.finish();
auto t3 = Clock::now();
cl_ulong copyToTime = copyToEvent.getProfilingInfo<CL_PROFILING_COMMAND_END>() -
copyToEvent.getProfilingInfo<CL_PROFILING_COMMAND_START>();
cl_ulong kernelTime = kernelEvent.getProfilingInfo<CL_PROFILING_COMMAND_END>() -
kernelEvent.getProfilingInfo<CL_PROFILING_COMMAND_START>();
cl_ulong copyFromTime = copyFromEvent.getProfilingInfo<CL_PROFILING_COMMAND_END>() -
copyFromEvent.getProfilingInfo<CL_PROFILING_COMMAND_START>();
std::cout << "Enqueue: " << t2 - t1 << ", Total: " << t3 - t1 << ", GPU: " << (copyToTime+kernelTime+copyFromTime) / 1000.0 << "us"<< std::endl;
}
Output:
Enqueue: 1804us, Total: 4322us, GPU: 10.832us
Enqueue: 485us, Total: 668us, GPU: 10.666us
Enqueue: 237us, Total: 419us, GPU: 10.499us
Enqueue: 282us, Total: 474us, GPU: 10.832us
Enqueue: 345us, Total: 531us, GPU: 10.082us
Enqueue: 359us, Total: 555us, GPU: 10.915us
Enqueue: 345us, Total: 524us, GPU: 10.082us
Enqueue: 327us, Total: 504us, GPU: 10.416us
Enqueue: 363us, Total: 540us, GPU: 10.333us
Enqueue: 442us, Total: 595us, GPU: 10.916us
I found this related question: How to reduce OpenCL enqueue time/any other ideas?
But no useful answers for my situation.
Any help or ideas would be appreciated.
Thanks
BR Troels