Frametime graph oddities

Discussion in 'Rivatuner Statistics Server (RTSS) Forum' started by oneoulker, Jun 1, 2024.

  1. oneoulker

    oneoulker Master Guru

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    Hello, I've a specific question I wanted to ask based on an observation. From what I gather, async framelimiter is supposed to have flat frametimes at frame start and jittery frametimes at frame presentation calculation point and for front edge sync, it should be vice versa.

    Now I'm trying a couple of games and I'm noticing that I get this behaviour with async indeed but not with front edge sync.

    For example in hogwarts legacy and miles morales, I get flat frametimes both at frame start and frame presentation with front edge sync. I'm trying to understanding why is that the case.
     
  2. BlindBison

    BlindBison Ancient Guru

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    I'm curious about this kind of thing too -- it's probably the case I'm misunderstanding something crucial, but I wondered for awhile now if it would be possible to have a limiter mode that puts a wait both at the start of the frame and at the end before frame delivery occurs so that the graph would perfectly flat as measured on either side (frame start or present). I expect input lag would be noticeably worse if you put a wait on both sides, just seems like then you'd have the holy grail of perfect frame times across the board.

    I've noticed in Cyberpunk Nvidia's driver limiter was very flat on both frame start and present but that's just a one off. I'll repeat the disclaimer that there's probably a good reason it doesn't work like that though as I don't fully understand the background logistics for how exactly the frame limiting works.
     
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  3. oneoulker

    oneoulker Master Guru

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    Yeah, I don't know really know when and where and what has changed but I cannot get smooth VRR framerate cap without front edge sync anymore. I remember a time when I'd just use regular old Async and games would look smooth. I now try ac mirage, at medium settings, with only 4.5 GB VRAM usage (8 gb vram card), GPU resources plenty, CPU resources plenty. I still get massive stutters on my screen physically, whereas "frame start" graph tells me it is perfect. And when I look at frametimes with frame presentation, they actually reflect what I observe on my screen with VRR.

    With front edge sync, somehow, both frame starts and presentations get flat frametime graphs, and visuals are noticably smooth without stutters.

    Problem with async and nvidia limiter in this game in particular is that it CONSTANTLY stutters and frame skips. I wonder if my monitor or GPU or cable broke and I cannot get stable presentation. I know it is supposed to be jittery but I'm failing to understand why it is... stuttery. Jittery shouldn't necessarily mean stutter but I'm literally getting large frametime spikes that result as stutters.

    Front edge sync do solve the problem kinda, but input lag is noticably increased as well. I do remember times where async + 60 FPS cap just used to work. I don't know what has changed between now and then..

    async
    https://imgsli.com/MjcyOTAz

    https://imgsli.com/MjcyOTAz/2/3
     
  4. Unwinder

    Unwinder Ancient Guru Staff Member

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    Start from reading and understanding what is rendering pipeline, without it you're just shooting in the sky. Ideal start-to-start timings alone NEVER promise you smooth animation. The same apply to ideal present-to-present timings. Perfectly flat start-to-start frametime is promising you just one thing: that CPU starts rendering each new frame at proper moment of time. CPU rendering time IS still variable. Presentation time IS still variable. GPU rendering time IS still variable. Display time IS still variable.
    Please use search, it was already explained in details.
     

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