2 Replies Latest reply on Aug 14, 2010 11:03 AM by Sheeep


      Run two queues parallel


      I tried to use gpu and cpu parallel.

      I created two differente queues in two contexts:

      queueCPU = cl::CommandQueue(Context, deviceCPU[0]);

      queueGPU = cl::CommandQueue(Context, deviceGPU[0]);


      I want to execute both queues parallel. 

      so I do:

      queueCPU.enqueueNDRangeKernel(this->Kernel[n], cl::NullRange, globalWorkSizeCPU, localWorkSizeCPU, NULL, NULL);


      queueGPU.enqueueNDRangeKernel(this->Kernel[n], cl::NullRange, globalWorkSizeGPU, localWorkSizeGPU, NULL, NULL);


      and after enqueueing I want to read the data back to host:

      queueCPU.enqueueReadBuffer(this->qBuffer[n].ioBuffer, true, 0,size, hostpointer);

      queueGPU.enqueueReadBuffer(this->qBuffer[n].ioBuffer, true, 0,size, hostpointer);


      If I do it that way, the queues don't run parallel. I think one queue is blocked, so the other can't enqueue, right?


      and if I do this (non blocking):


      queueCPU.enqueueReadBuffer(this->qBuffer[n].ioBuffer, false, 0,size, hostpointer);

      queueGPU.enqueueReadBuffer(this->qBuffer[n].ioBuffer, false, 0,size, hostpointer);

      they run parallel, but I don't get the right result.



      How can I block the memory, and execute the queues parallel?




      P.S. sorry for not posting complete code, but is in different classes, so I thinks it's to much. If needed I can make an simple example...

        • Multiqueue

          Take a look at SimpleMultiDevice sample where all combinations explained.

            • Multiqueue

              Thank you for your answer, 

              I'm not familar with the sdk-environment, but if i am right, i have to create some threads with an multithreading framework. like openmp?


              I will try to use sdk-environment instead of khronos opencl binding.



              I tried with openmp, works wonderfull (if i don't need any synchronization).

              is there a multithreading extension in opencl for the host?