4 Replies Latest reply on Jan 3, 2012 2:22 PM by MicahVillmow

    Catalyst 12.1 preview decreased performance

    antzrhere

      I know I mentioned something similar when upgrading to Catalyst 11.11, which turned out to be a bug in my code :-/, but there definately seems to be a significant drop in performance using these drivers (-18%).

      Apparently others are experiencing a similar drop in performance:

      https://bitcointalk.org/index.php?topic=54693.40

      I realise these are preview drivers only, but it is strange and concerning given the degree of performance impact...Unfortunately I'm going to have to wait for the final release before I can restore performance as re-installing 11.12 doesn't revert the problem (obviously the uninstall didn't remove everything).

      Has anyone else experienced these same performance drop using Catalyst 12.1 preview drivers (Win 7 64bit)

        • Catalyst 12.1 preview decreased performance
          bubu

          New drivers usually favour new cards. If they optimize them for old cards then their new products won't be as amazing as they should be :D

          Nothing new, really :p

            • Catalyst 12.1 preview decreased performance
              Meteorhead

              I doubt this would be behind the performance degradation. New architecture sounds very powerful, but even if we suppose it does not meet expectations (as did bulldozer), degrading legacy cards that do perform well is equal to an own-goal for AMD. Software support for older generations is not... well... not the best, to put it nice. If they shift the quality of support in a negative direction intentionally, they will lose their scarce number of present customers.

              NV does have the luxury of being able to do this, but that is because they have HEAPS of customers already set on CUDA. They can let themselves fall OpenCL behind when it comes to their own SW support. However, AMD cannot.

                • Catalyst 12.1 preview decreased performance
                  antzrhere

                  Interestingly, on my project increasing the workgroup size from 64 upto 128 reclaims alot of the lost performance - only 3% down from Catalyst 11.12 now.

                  - The interesting part about it is that increasing the workgroup size to 128 had absolutely no performance gain from Catalyst 11.2-11.12..

                  The code has a lot of conditional code (its a raytracer), so there is alot of potential latencies to hide, but it never made any difference before.

                  ...curious.

                   

                   

              • Catalyst 12.1 preview decreased performance
                MicahVillmow
                AMD does not intentionally decrease performance except in the case to fix bugs. This might be a case where we had an optimization enabled that was being overly aggressive and was generating good code, but in a corner case it failed so we had to decrease the aggressiveness of the optimization.