Triple buffering question

Discussion in 'Videocards - NVIDIA GeForce Drivers Section' started by tsunami231, May 16, 2014.

  1. tsunami231

    tsunami231 Ancient Guru

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    If TB=on with 60hz I will see fps between 30 and 60fps ie 40,45,50 etc yes?

    If TB= off and double buffering is used If pc cant keep 60 fps it will drop to 30 and there will be no fps between 30 and 60?

    Am i correct am I understanding it or is that wrong?
     
  2. mbk1969

    mbk1969 Ancient Guru

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  3. tsunami231

    tsunami231 Ancient Guru

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    no i talking about triple buffer that works WITH vsync I not talking about the vsync function I talking about the TB function it self

    Nor does what you link help with my question
     
  4. Guy.J.

    Guy.J. Active Member

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    Yes, but only when you are severely GPU limited.
     

  5. tsunami231

    tsunami231 Ancient Guru

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    thanks
     
  6. mbk1969

    mbk1969 Ancient Guru

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    Please, can you elaborate? I want to understand...
     
  7. Guy.J.

    Guy.J. Active Member

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    How much? :)

    Double buffering:
    Frame A is on screen. Frame B is being rendered. If B is not completed before the next screen redraw (1/60th of a second) the GPU will have to wait for the next screen redraw (another 1/60th of a second) before flipping the buffers. The GPU cannot start rendering the next frame until this happens because there is no empty buffer to render to. If this happens consistently (because the GPU is incapable of rendering the current scene in less than 1/60th of a second) then you are locked at 30fps - two screen refreshes per buffer flip, even if your card could be doing 50fps with vsync off.

    [Note that if you are CPU limited and not GPU limited then frame rate is limited only by how quickly the CPU can supply the GPU with frames, so you can get say ~45fps even double buffered].

    FIFO triple buffering (sometimes called "GPU render ahead" by people who insist that TB is only TB if it uses LIFO queuing rather than the far more common FIFO) solves the problem by having an extra frame buffer in-between A and B, which means when the game is GPU limited there is always a buffer ready to be rendered to (no need to wait for screen refresh before starting the next frame).
     
    Last edited: May 17, 2014
  8. Cyberdyne

    Cyberdyne Ancient Guru

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    I think we understand how double and triple buffering works, but being GPU limited doesn't play a direct roll in either case. Anything that puts your FPS below 60 with double buffering will pull you to 30 fps on a 60hz monitor. Or at least that has been my understanding for a long time.
     
    Last edited: May 17, 2014
  9. Guy.J.

    Guy.J. Active Member

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    I thought it an odd question, but he did ask.

    No, because with vsync enabled the CPU queues frames (CPU render ahead minumum 1 frame ever since 3xx drivers). So you basically get "CPU triple buffering" if you will (or quadruple or quintuple depending on render ahead setting).
     
  10. Cyberdyne

    Cyberdyne Ancient Guru

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    The only time I've seen that happen is when I artificially limit the frame rate slightly below 60 with vsync+double buffering. Every other time the FPS dips below 60 (settings to high or what-have-you) I would drop to 30. Am I to assume that every time I go below 60 fps it's because I'm GPU limited?

    You know what, nevermind. My brain hurts now.
     

  11. tsunami231

    tsunami231 Ancient Guru

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    My understanding is render ahead option and actual TB are to diffrent ways of actaul doing the same thing, other then one method can drop old frames and the other will render the old frames.

    Im just trying to fiqure out if Swtor actual use TB or not. which almost impossible seeing how bad the engine is, I honestly never seen any game atlest ones I have that 60fps ever drop to 30 if i cant keep 60 fps and I always have vsync on.

    And know my gpu isnt the issue it does 60fps fine hell its does 111 fps the game is actaul capped at. and it general will do with this only 70% gpu usage.

    And soon as fps tanks to 20's gpu usage drop like brick to like 20% if that. mean while according to task manager my cpu usage never really goes past 30% at any time in the game. which bring me back to the game engine which is used that is ****

    Thank for the info either way
     
    Last edited: May 17, 2014
  12. Guy.J.

    Guy.J. Active Member

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    SWTOR is old, probably not multithreaded so only one CPU core in use?
     
  13. Guy.J.

    Guy.J. Active Member

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    From PC Gaming Wiki:
    http://pcgamingwiki.com/wiki/Star_Wars:_Knights_of_the_Old_Republic

    Might help you.
     
  14. RealNC

    RealNC Maha Guru

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    Games have so many buffers these days, it's hard to tell. It seems every new game that comes out adds some more buffers. At least that's how it feels like input-lag-wise. Must be because of multi-threading and keeping the CPUs fed. With 4 CPUs preparing frames, you're gonna end up with 4 frames on a buffer... If this continues, FPS games are going to feel like driving a boat very soon now.

    Also, it's been a long while since I saw a game drop to 30FPS when it can't make 60 with V-Sync on.

    Buffer bloat everywhere these days.
     
  15. Cyberdyne

    Cyberdyne Ancient Guru

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    I feel like I can ignore most of this if I just ignorantly use adaptive vsync. I feel that is the way to go if you can't keep a game at 100% fps refresh rate and really want vsync.
     

  16. RealNC

    RealNC Maha Guru

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    G-Sync will hopefully come to the rescue soon. Then we can end this madness once and for all.
     
  17. tsunami231

    tsunami231 Ancient Guru

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    the mmo Starwars the old republic= Swtor

    Kotor is Kotor

    Both Kotor and Kotor II run perfectly
     
  18. Guy.J.

    Guy.J. Active Member

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    Ooop :bonk:
     
  19. yasamoka

    yasamoka Ancient Guru

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    Who said that the CPU is limited to serial, single-core operations when preparing a single frame?

    But yes I agree, many games just feel too bloaty and not as snappy as, say, CS:GO.
     
  20. RealNC

    RealNC Maha Guru

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    CS:GO feels laggy if you played older games. Compare for example Half-Life 2 input lag with V-Sync vs CS:GO. Or go even further back to Quake 3 and Half-Life 1. Compared to that, CS:GO feels like the laggiest game ever.
     

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