1 Reply Latest reply on Mar 7, 2013 10:37 PM by himanshu.gautam

    Kernel on AMD "dies" after being idle 100ms

    tgreen

      I am doing the following test

       

      0 : compile kernel for GPU

      1 : start timing

      2 : Launch kernel solving a problem returning a result

      3 : stop timing

      4 : Sleep(100ms)

      5 : show timing

      6 : goto 1

       

      I have experienced that using a NVidia card the time measured is in my case always 25ms with or without the sleep in line 4.

      Using an AMD card I see the time as 32ms when sleeping and 16 ms when not sleeping.

      If I change the sleep to some value less than 100ms, then it does not affect the gpu kernel time.

       

      For both NVidia and AMD I see the first launch as taking longer and for both the following  times are lower.

       

      Is there a well described flushing/pausing/something of the kernel on AMD devices which I should know about?

       

      Amd timing with Sleep inbetween calls

      GPU:55

      GPU:35

      GPU:35

      GPU:35

      GPU:35

      GPU:32

      GPU:32

      GPU:32

      GPU:32

      GPU:32

       

      Amd timing without sleep between calls

      GPU:49

      GPU:16

      GPU:15

      GPU:15

      GPU:16

      GPU:16

      GPU:16

      GPU:16

      GPU:15

      GPU:16

        • Re: Kernel on AMD "dies" after being idle 100ms
          himanshu.gautam

          Hi Thomas,

          Nice problem. Lets get to the bottom of it.

          But just to remind everyone, a thread can be solved by many people, so better give full details on every new thread.

          CPU, GPU(s), Driver Versions, SDK Version, OS , Bitness (32 or 64).

           

          It will also help to resolve the issue quickly if you can attach a zip file, for easy reproduction. If required use the kernel launch testcase i attached in your previous thread, or use other SDK Samples.