I develop app that requires data to be transferred back to host almost after each kernel call (some flag returned).
Usuall I do processing in such way:
So, queue synched on blocking read. This works OK on AND GPUs/APUs with few % CPU load, but on Intel GPU this leads to constant 100% CPU usage (app fully use 1 CPU core constantly).
When I tried such sequence:
CPU load was dropped considerably. So, looks like synching on clFinish() and on blocking buffer read works quite different for Intel OpenCL runtime. Why so? Does this in agreement with OpenCL standart ?