title: SIMD-8,SIMD-16 or SIMD-32 in opencl on gpgpu
body: <p>I read couple of questions on SO for this topic(SIMD Mode), but still slight clarification/confirmation of how things work is required.</p>
  
  <p><a href="https://stackoverflow.com/questions/25630209/why-use-simd-if-we-have-gpgpu">Why use SIMD if we have GPGPU?</a></p>
  
  <p><a href="https://stackoverflow.com/questions/14959065/simd-intrinsics-are-they-usable-on-gpus">SIMD intrinsics - are they usable on gpus?</a></p>
  
  <p><a href="https://stackoverflow.com/questions/27333815/cpu-simd-vs-gpu-simd">CPU SIMD vs GPU SIMD?</a></p>
  
  <p>Are following points correct,if I compile the code in SIMD-8 mode ?
  1) it means 8 instructions of different work items are getting executing in parallel.</p>
  
  <p>2) Does it mean All work items are executing the same instruction only?</p>
  
  <p>3) if each wrok item code contains vload16 load then float16 operations and then vstore16 operations only. SIMD-8 mode will still work. I mean to say is it true GPU is till executing the same instruction (either vload16/ float16 / vstore16) for all 8 work items?</p>
  
  <p>How should I understand this concept?</p>