Considerations for Multiple GPUs for many outputs in MadMapper
  • Lumenarius
    member
    Posts: 37
    Joined: Tue Oct 24, 2023 11:32 pm

    Considerations for Multiple GPUs for many outputs in MadMapper

    by Lumenarius » Mon Oct 14, 2024 9:23 pm

    Finally getting back to pushing the limits for what is possible with projection mapping for MadMapper and a Windows 10/11 machine.

    In the past we have used a computer with a NVIDIA T1000 GPU and have successfully attached x3 DataPath Fx4 units to achieve a x12 1920 x 1080 output setup where the 1st output is the Main Display.

    However, some projects are starting to require more than x12 HD outputs, sometimes x20, or sometimes x6 4K outputs, etc, and I am looking into ways to achieve this.

    Of course we could buy a few Barco, Christie, or Hippo servers but I think we can achieve nearly the same performance for less than $xxx,xxx per unit. Seriously they are so expensive!

    Right now we are looking at a system that can make use of x2 NVIDIA A4000/A5000 cards while also maxxing out the RAM and CPU.

    If this all works and we can expand x7 of the outputs (keep x1 as main display!) from the cards into x7 Fx4s which will give us a maximum of x28 HD outputs. Sweet!

    With that, what caveats or considerations are necessary for getting another GPU involved to achieve a "Dual GPU" setup with MadMapper? The questions I can think of are as below.

    >> As long as Windows can see the additional outputs will MadMapper be able to make use of them?

    >> Are there any specific cards or card makers that MM does not play well with? I.e. AMD vs NVIDIA?

    >> Am I right to understand that this additional card does not boost performance y sharing the work load but rather will just provide additional outputs?

    >> When it comes to synchronizing the cards to prevent frame tearing or the like does this happen automatically or is there some sort of software sync or physical sync generator like as used when linking multiple Fx4 units together such as the Blackmagic Design CONVMSYNC?

    >> Without actually testing the unit is there anyway to speculate on what the maximum resolution for the media file would be? Could we still make use of 8K+ content with a favorable GPU Codec or do all of these outputs, which may be arbitrary slices with mesh warping, start to eat into the performance?

    Thank you for making killer software! Still miles ahead of everything else and we have tried it all.
  • xrchitect
    junior Member
    Posts: 7
    Joined: Wed Oct 25, 2023 11:34 am

    Re: Considerations for Multiple GPUs for many outputs in MadMapper

    by xrchitect » Mon Oct 21, 2024 4:49 am

    I'm still new to this but I thought nvidia quadros, using nvidia mosaic software would elimate screen tearing and keep everything in sync across gpus. From what I gather, there is a performance cost from syncing, but it may not be noticeable, if there is enough memory in a single GPU to process everything. IIRC only 1 GPU can be used to process everything, and the other GPUs merely receive it, and cannot share in the workload.
    To reduce GPU overhead, also consider cpu codecs like HAP or NotchLC.

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