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MSAA increases input lag?

Discussion in 'Videocards - NVIDIA GeForce Drivers Section' started by dezo, Feb 20, 2018.

  1. dezo

    dezo Member

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    Recently I tried some alternative methods to minimize input lag in games @60Hz using VSync without external frame limiter. There are two key settings in NVInspector:
    - Maximum pre-renderer frames -> affects D3D API
    - Maximum frames allowed -> affects OpenGL/Vulkan API
    Setting appropriate parameter to 1 per game reduces input lag by rendering less frames ahead (even in Doom 2016 on Vulkan). In some games this introduces stuttering (ie. Cod MW1/2/3, Metro redux), at least on my end with GTX1080/388.31, so it's best to set it per game, not globally. But there is some strange thing I didn't knew about - in some older games, like RTCW, Prey, all Quakes and some others, mostly OpenGL titles, any kind of Multisample Antialiasing adds more frames to the queue, so MSAA in these games actually increases input lag when using VSync. Is that caused by MSAA implementation in the engine? I mean are more frames needed to process AA? I thought geometry based AA like MSAA doesn't need more frames to process...
     
  2. khanmein

    khanmein Ancient Guru

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    No such thing. MSAA can caused other issue, but not input lag.
     
  3. AsiJu

    AsiJu Ancient Guru

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    I doubt MSAA or any AA method would increase amount of drawn frames sent to back buffers hence increasing lag but I'm no expert on the matter.

    Besides if you set prerender limit to 1 shouldn't matter anyway.
     
  4. dr_rus

    dr_rus Ancient Guru

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    MSAA lower your fps and this results in input lag increase. That's all.
     
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  5. dezo

    dezo Member

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    Thanks for responses. This must be a thing in older games then. Like I said, I am seeing this mostly in ancient OpenGL titles, where FPS are well above 300 all the time with all settings maxed. So with VSync @60 Hz it never drops under 60 FPS - I pretty much doubt it has to do something with performance. Maybe some IDtech 3 feature.
     
  6. -Tj-

    -Tj- Ancient Guru

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    It adds more driver overhead, so yes it adds more lag.

    Same by FEAR1 msaa & transparency AA by older opengl games. E.g. Prey, Doom3.
     
  7. dr_rus

    dr_rus Ancient Guru

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    No it doesn't.

    Driver overhead don't add any lag.

    Particular MSAA implementations may add whatever due to how they reconfigure the rendering pipeline to add MSAA. But this is app specific.
     
  8. -Tj-

    -Tj- Ancient Guru

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    It adds higher latency - higher driver overhead.
     
  9. dr_rus

    dr_rus Ancient Guru

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    Driver runs on CPU and has no effect on the input lag unless you mean that it impacts performance resulting in lower fps.

    But in any case, MSAA doesn't affect any driver overhead.
     
  10. dezo

    dezo Member

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  11. Agonist

    Agonist Ancient Guru

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    Except FEAR 1 was DX9.....
     
  12. -Tj-

    -Tj- Ancient Guru

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    By FEAR - MSAA
    By ID4 engine - TrAA
     
  13. MrBonk

    MrBonk Ancient Guru

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    FEAR and other games running on the engine from within a few years use FSAA.

    Also, until someone does concrete testing with actual numbers. Anyone claiming otherwise is full of it.

    I welcome someone to test a game without and with AA running at the same framerate with no performance drops to actually definitively test this. (Preferably whoever did the latency tests on BlurBusters)
    I doubt MSAA or any kind of AA adds any kind of significant latency.
     
  14. RealNC

    RealNC Ancient Guru

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    Just get a g-sync display for your 1080 and forget about the vsync input lag nonsense. It's quite liberating to not give a f about increased input lag with higher graphics settings and vsync :p
     
    Last edited: Feb 21, 2018
  15. dr_rus

    dr_rus Ancient Guru

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    If MSAA actually adds input lag then it will add it on all displays, it will add it even without vsync. Which is why I highly doubt that it does.
     
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  16. dezo

    dezo Member

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    @RealNC: Soon :) My 32" 1440p from BenQ developed some ugly stains in backlight, so it's about time to get a new one.
    I was just in the mood for some retro gaming and tweaking. Tested the AA thing some more and it affects only old OpenGL engines with VSync active - at least on my end. Using brute force with 4x DSR instead of MSAA looks comparable and doesn't add any additional lag. Weird.
     
  17. -Tj-

    -Tj- Ancient Guru

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    If you're questioning my remark, it is true. I've played over 2000hrs Fear multiplayer, think I will know when it lagged or not @ each setting..

    Even now with faster gpu, DSR 4k + 4xmsaa adds noticeable input lag vs just 2x.
     
  18. dr_rus

    dr_rus Ancient Guru

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    He's saying that FEAR doesn't use MSAA.
     
  19. -Tj-

    -Tj- Ancient Guru

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    And you give it a rest, no one asked you, thanks.
     
  20. dr_rus

    dr_rus Ancient Guru

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    I will say whatever I want whenever I want and you won't be able to tell me when to do what, thanks or not.
     
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