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Feature Request Make HDRP more scalable on laptops

Discussion in 'High Definition Render Pipeline' started by bitinn, Apr 3, 2021.

  1. bitinn

    bitinn

    Joined:
    Aug 20, 2016
    Posts:
    961
    Hi all,


    After 1.5 years with HDRP I thought I would comment a bit about my experience using it across different hardwares. On mid-high end PC, with popular baseline graphics cards like 960 or 1060, HDRP proved to be very scalable, and scene complexity doesn't create too much problem for us, which we like a lot.

    The downside of HDRP's predictability, is when it comes to laptops, say a MBP 2020, we start off with a sub 60fps performance.

    While there are many options in HDRP Asset and its Frame settings. We found most of them doesn't do much when you are on laptops. Except for Dynamic Resolution, which unsurprisingly, reliably improve performance. (Turning off volumetric and space-screen effects also helps, but not by a lot.)

    So we know where laptop hardware bottlenecks are, and we know HDRP can target these platforms, is there something we could do to make HDRP more usable?

    Thx, love to hear from Unity team and HDRP game devs!


    (Surely someone is going to suggest URP, and I had worked with URP before: the problem with URP is it doesn't scale well over scene complexity, partly due to its simple lighting pipeline.)

    (An alternative would be custom SRP, which I also written a few on my own time, BUT in actual project, we just don't have the manpower to manage this complexity.)
     
  2. Remy_Unity

    Remy_Unity

    Unity Technologies

    Joined:
    Oct 3, 2017
    Posts:
    685
    Does your comparison take in consideration the very high pixel density of a MBP ?
    If you're comparing fps from a 1080p fullscreen render to the 2880x1800 resolution of a MBP without dedicated GPU, I'm not surprised that the performance greatly drops.
     
  3. bitinn

    bitinn

    Joined:
    Aug 20, 2016
    Posts:
    961

    So first of all, yeah, I am aware that Retina screen + 60 fps is difficult for a laptop. Even if it had good GPU (good fillrate), heat throttling would have capped its performance eventually.

    However, I am interested in creating a faster HDRP baseline setting for MBP.

    So far, even if I turned off literally every feature HDRP offers (in Asset and in Frame settings, and of course overwriting the default post processing volumes), just by running in full Retina resolution, I can barely maintain a stable 30 fps.

    Knowing that the rendering is fillrate bound, I can reduce the resolution to about 60%, then I can get around 50~60 fps.

    So what I am saying is: there is no other way for dev to make HDRP scalable on laptops, except for dynamic resolution. I hope unity team can provide more insights or solutions.
     
  4. bitinn

    bitinn

    Joined:
    Aug 20, 2016
    Posts:
    961
    Or to put it in another way:

    HDRP's GBuffer layout appears to be fixed, we are not actually saving that much performance by disabling features (It mostly just render less). It would be great to have some ballpark estimate on how much memory is needed (like the built-in deferred path) and hence estimate whether it is possible to make HDRP run on laptops.

    (Other than running in 1280x720 :))
     
  5. BattleAngelAlita

    BattleAngelAlita

    Joined:
    Nov 20, 2016
    Posts:
    400
    Maybee forward? HDRP Gbufer are huge, and get bigger with every release.
     
    Ruchir likes this.