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In Multi-Gpu scenario, Primary GPU always performs better than secondary GPU

Discussion in 'Videocards - AMD Radeon' started by SunGeo, Sep 20, 2019.

  1. SunGeo

    SunGeo New Member

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    GPU:
    AMD WX5100
    In my software, i have a functionality to playback of images. This playback needs to maintain 30 fps.

    My machine has 2 AMD WX5100 GPUs with 2 monitors connected to each GPU.

    When one of the monitor is made the “Make this my main display” from Control Panel\All Control Panel Items\Display, then this GPU becomes the primary GPU and the other GPU becomes the secondary GPU.

    After this when i playback the images in both the monitors, the monitor connected to the primary GPU gets 30 fps playback, whereas the playback in the monitor connected to the secondary GPU gets only 24 fps.



    Now if the main display setting is reversed, the performance will also be reversed.



    Why is this performance difference based on the primary and secondary GPU. Please help.
     
  2. Fox2232

    Fox2232 Ancient Guru

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    GPU:
    5700XT+AW@240Hz
    Hi, please state OS, Rendering API used, Monitor configuration used. (Are those 2 separate displays or are they in group?)
     
  3. SunGeo

    SunGeo New Member

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    GPU:
    AMD WX5100
    OS: Windows 10
    Rendering API: ID3D11DeviceContext: Draw
    Monitor Configuration : 2 monitors with 1 as "main" display and the other "extended"[As configured in Control Panel\All Control Panel Items\Display\Change Display Settings]
     
  4. Fox2232

    Fox2232 Ancient Guru

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    GPU:
    5700XT+AW@240Hz
    I was afraid you say Windows 10.
    Since one of newer builds ~1.5 years ago, I faced same issue. Primary application gets GPU priority to point that all secondary applications choke. (Even on primary screen.)
    My problem was with OBS and GPU accelerated processing. I went through MSDN to see all registry for scheduling and prioritization of workload. Just to find that since given build, they had no effect.

    In my case, I got "help" through limiting fps enough to have a lot of spare GPU cycles. Which is likely to no help to you.

    What happens in case you run those playback applications on primary screen? Does one still have issue?
    What is GPU load reported by GPUz/Task Manager?
     

  5. SunGeo

    SunGeo New Member

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    GPU:
    AMD WX5100
    Thank for the info.
    When both the playback applications are executed asynchronously through the primary GPU, i get the expected performance.
    But while running them simultaneously, a decrease in performance is noticed.

    GPU load of both the GPUs are 0% during the playback(Both when connected to different gpu and when both connected to 1 gpu)
     

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