openSUSE Touts Improved Multi-GPU Switching Support

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  • ahrs
    Senior Member
    • Apr 2021
    • 583

    #11
    Originally posted by pWe00Iri3e7Z9lHOX2Qx View Post

    But most people don't want to reboot at all to select which GPU to use. The system should be smart enough to use the dGPU by default for things you are likely to want to run on the beefier GPU (e.g. Vulkan games). And give them the ability to override / manually set as necessary.
    We could have solved this problem ages ago with metadata in .desktop files using PrefersNonDefaultGPU​, except in typical Linux fashion apparently this was generalised to the point of uselessness where nobody knows what it's supposed to mean. Taken literally (which is its actual meaning apparently) it means to run on whichever GPU is the non-default GPU which could very well be the systems iGPU but could also be some other discrete card, there's no way of knowing:

    counter-part to #7089 PrefersNonDefaultGPU is broken by design, intended to mean "Use the Discrete GPU if possible" but instead generalized to mean "Use anything that we aren't using by default" wh...

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    • pWe00Iri3e7Z9lHOX2Qx
      Senior Member
      • Jul 2020
      • 1589

      #12
      Originally posted by the-burrito-triangle View Post
      Weird. The multiplexer should be able to switch inputs in real time... WTF are the laptop vendors / OS people doing wrong here? Maybe it's a BIOS problem, where the low level settings aren't accessible to the OS due to "security" reasons?
      To a large degree this already works out of the box on all AMD (as in multu-gpu) systems, and I assume all Intel systems (and probably Intel + AMD and AMD + Intel if anyone builds those). With an AMD iGPU + AMD dGPU, it will automatically run Vulkan workloads on the dGPU. For OpenGL, you have to force it yourself (or through .desktop entry metadata). It's the same experience as using a Zen 4 / Zen 5 desktop with the displays wired up to the motherboard iGPU ports but having a dGPU installed.

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      • Alexmitter
        Senior Member
        • Mar 2019
        • 1134

        #13
        Originally posted by the-burrito-triangle View Post
        Now that I think about this, shouldn't the mux be accessible via i2c (or i3c)?
        i3c WHAT? the 2 in i2c stands for it containing 2xi. Inter-Integrated Circuit​.

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        • Quackdoc
          Senior Member
          • Oct 2020
          • 5071

          #14
          Originally posted by the-burrito-triangle View Post
          Weird. The multiplexer should be able to switch inputs in real time... WTF are the laptop vendors / OS people doing wrong here? Maybe it's a BIOS problem, where the low level settings aren't accessible to the OS due to "security" reasons?

          Anyways, on a desktop machine with multiple GPUs, I have no problem using the dGPUs headless (without a display attached) and outputting all video through the iGPU. The multiplexer approach is much more performant since the PCIe bus isn't being used to send data from one GPU to the other, but clearly it is still a shit show because no one understands how to configure the BIOS setting from the OS and maybe do a rescan of the PCIe bus if the dGPU was powered off and then on with the mux state change. This honestly shouldn't be that hard to do...
          as far as I know, this is more of a compositor problem.

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