7 Replies Latest reply on May 4, 2015 5:35 AM by pinform Branched to a new discussion.

    Out of order queues

    boxerab

      I've turned on out of order queues on my project running on HD 7700.

      This significantly improves performance, I highly recommend it!

      Only caveat is that you have to manage kernel sequence yourself, using events.

       

      My question: which AMD cards support out of order queues?  Also, is this feature purely on

      the driver side, or is there silicon required to support it? 

       

      Thanks!

        • Re: Out of order queues
          thesmith

          Out of order queues device-side queues is part of the OpenCL standard since 1.0. Every GPU should support it AFAIK. For host-side it depends on the implementation. I know of one device that does not! Altera clearly states in its programming guide that its runtime does not support such queues.

            • Re: Out of order queues
              dipak

              As per OpenCL spec, supporting out-of-order queue is not a mandatory feature. So, I guess, if you pass the out-of-order flag during command queue creation, the implementation may ignore this flag if out-of-order is not supported by the platform.

              1 of 1 people found this helpful
            • Re: Out of order queues
              dipak

              AFAIK, out-of-order host-side queues are not currently supported on AMD platform, but out-of-order device-side queues are supported. However, certain devices have hardware support which can simultaneously handle multiple commands from multiple queues. Hence, they can provide a significant performance boost if many independent tasks are enqueued concurrently to the device via multiple opencl queues.

              Anyway, as you mentioned, you can see a performance improvement if you turns on the out-of-order mode. Its really interesting. Could you please be more explicit about the commands you enqueued and how? Meanwhile I'll check with some experienced folks for more details.

               

              Regards,