title: OpenCL kernel execution does not start until clFinish or clWaitForEvents is called
body: <p>I am trying to run a kernel on the GPU and do additional computation on the host (CPU). I see this effect:</p>
  <p>only the kernel needs around 2000 ms:</p>
  <blockquote>
  <p>clEnqueueNDRangeKernel ...</p>
  <p>clFinish (or clWaitForEvents, I tried both)</p>
  </blockquote>
  <p>I simulated additional computation on the CPU with sleep(10):</p>
  <blockquote>
  <p>clEnqueueNDRangeKernel ...</p>
  <p>sleep(10);</p>
  <p>clFinish (or clWaitForEvents)</p>
  </blockquote>
  <p>In theory the kernel should run on GPU and after the 10 sec sleep the kernel should be finished. But time measuring said it all needs 12000ms instead of 10000.</p>
  <p>Does clFinish or clWaitForEvents invoke the kernel to start or did I miss something?</p>
  <p>I'm using an AMD Fusion CPU/GPU und Linux.</p>
  <p>Thanks a lot.</p>