2 Replies Latest reply on Sep 18, 2018 11:36 AM by dave_g

    Doom Vulkan - Enhanced Sync Stuttering with RX560

    dave_g

      I've tried several variants of Adrenaline drivers in order to get a decent Doom experience on a RX560 on Vulkan, up to the latest optional release. The problem with the game's built-in vsync is that it will vary wildly whenever it goes below 60, bounce from 30-60 and significant stuttering. No-vsync is an option of course, but I also hate tearing. So Enhanced Sync would seem to be ideal. However, in practice...

       

      The problem is that whenever it's enabled, I get massive stuttering above 60fps, and while the drops below are far smaller than with vsync according to Doom's frame rate statistics, it certainly never feels like a smooth experience regardless of the FPS. Also, I never notice any tearing - which according to the explanation of Enhanced Vsync, I should see when it dips below 60. I just get a constant stutter. Note this is not unique to Doom with Enhanced Sync (I find it stutters frequently in other games too, Doom is just where I need it most), it's just never lived up to its promise for me.


      Frame Rate Target Control (FRTC): If I force this to 60 along with turning on ES, then the stuttering above 60 is gone - for a bit. The problem is that the CPU spikes above 16.7 ms are frequent, with just Enhanced Sync and FRTC not enabled my CPU (Pentium G4560, low-end I know but not a bottleneck for Doom) usually stays under 10ms according to Doom's graphs. With FRTC enabled though, I see constant GPU spikes of 60ms+ every few seconds, every few seconds you get a momentary frame-rate "skip" where it seems to jump several frames at once regardless of the activity on-screen.

       

      The only way to get a reliable 60fps without stuttering is to just leave vsync off and use FRTC to lock to 60, but that means even at a perfect 60 I still get this slow-moving tear line across the screen as I pan around. It's the best option so far, but really Enhanced Sync should not be behaving as it is as is my understanding of it.

       

      Anyone else?

        • Re: Doom Vulkan - Enhanced Sync Stuttering with RX560
          kahless_uk

          The only way I get expected performance from Doom with an RX480 is to turn power efficiency off before playing then it stays at 60fps consistently with vsync, if I leave power efficiency on as I do with most games it really struggles with vsync frequently dipping to the low 40s and stuttering when it is at 60.

           

          I'm not entirely sure if the RX500 series cards have a power efficiency toggle in the drivers (my eldest's 570 doesn't) but you could try increasing the power limit in wattman

            • Re: Doom Vulkan - Enhanced Sync Stuttering with RX560
              dave_g

              Thanks, but it doesn't seem to really an issue of the card not delivering to expectations in my case, it's performance is right where it should be when I look at other Doom benchmarks for this particular card on the web. It's getting very close to a mostly-constant 60 at 1080 on medium with some extra features enabled.

               

              The issue is basically Doom's wonky frame pacing with vsync enabled (which seems to be strictly double-buffered which is actually rare in games these days) and in situations this is where enhanced sync would be ideal for, but it just introduces even more stuttering, as it does in many games in my experience - D3D or Vulkan. This has been apparently been an issue for a subset of users since its intro.

               

              However, I did find a workaround - RivaTuner Statistics Server. Basically I used this to limit the frame rate to 60, and kept Doom's in-game vsync on, and surprisingly this fixes the huge drops to 30-40fps it had before when the framerate would go under 60. It's still noticeable when it does, but it behaves as you would expect - slight stuttering as opposed to falling through the floor without it. AMD's own frame rate control does nothing for smoothness with Doom's vsync and only helps with vsync off, but then I still get some constant tearing. This seems to be the best compromise.