Search Unity

  1. Good news ✨ We have more Unite Now videos available for you to watch on-demand! Come check them out and ask our experts any questions!
    Dismiss Notice

Use of multiple video cards running multiple instances of a Unity standalone player on Windows

Discussion in 'Windows' started by PaulVA, Jan 29, 2016.

  1. PaulVA

    PaulVA

    Joined:
    Mar 17, 2015
    Posts:
    7
    I have an unusual use case. In Windows 10, running a Unity standalone application we're building, we are able to run multiple instances of the application simultaneously on the same PC (on the order of a dozen). The application renders stuff and records video (using AVPro Movie Capture), and that currently works. We want to generate these videos as fast as possible. So, we would like to take advantage of multiple video cards on the same machine.

    By default, would Windows/Unity just use one of the installed and enabled video cards, or would it automatically take advantage of other card(s)? (I understand that SLI would make multiple video cards act as one, more powerful, video card...would that actually help when running 12 instances of the application?)

    I've read the docs for the "-adapter N" command line argument, but using that does not seem to make a difference in my tests with two video cards in one machine. (My hope would be, that in launching the 12 instances, I could start 6 of them on one "adapter" and the other 6 on the other "adapter".) Does that make sense? And is "N" zero-based, so that "0" means the first adapter found, and "1" means the second, etc?

    Using Unity 5.0.1f1 currently. Any help would be greatly appreciated.
     
  2. Tautvydas-Zilys

    Tautvydas-Zilys

    Unity Technologies

    Joined:
    Jul 25, 2013
    Posts:
    7,693
    Hi,

    -adapter option actually refers to d3d9 adapters, which are actual "outputs" of the graphics card, for example, monitors. To force a specific graphics card, use the "-gpu" flag. For example, launch one instance with "-gpu 0", and another instance with "-gpu 1". By the way - this will only work if you're using D3D11 or D3D12 as your graphics API in player settings.
     
    jpfranssen and PaulVA like this.
  3. PaulVA

    PaulVA

    Joined:
    Mar 17, 2015
    Posts:
    7
    Thanks! I was not aware of the "-gpu" command line argument. I'm using this now, but it's not clear to me that I'm using it correctly. I'm using TechPowerUp GPU-Z to monitor GPU use (watching the "Memory Used" and "GPU Load" (%) closely. In running my tests, I generally see the first GPU being used even if I pass "-gpu 1". I verified that in File -> Build Settings... -> PC, Mac & Linux Standalone -> Player Settings... that "Use Direct3D 11*" is checked on. (I don't see an option for D3D12...perhaps because I'm still on Unity 5.0.1f1?) Also, I'm generally running in windowed mode, not full-screen...does that make a difference?
     
  4. Tautvydas-Zilys

    Tautvydas-Zilys

    Unity Technologies

    Joined:
    Jul 25, 2013
    Posts:
    7,693
    I'm afraid the "-gpu" flag was only added in Unity 5.2 :(.
     
    PaulVA likes this.
  5. PaulVA

    PaulVA

    Joined:
    Mar 17, 2015
    Posts:
    7
    Ah, thanks
     
  6. jpfranssen

    jpfranssen

    Joined:
    Apr 7, 2014
    Posts:
    12
    Thanks, bit late though for us ;). In 4.x we've managed to get around this using a DX11 wrapper dll. Let's see if we can get rid of this now :).
     
  7. ebadier22

    ebadier22

    Joined:
    Jun 20, 2017
    Posts:
    9
    Hi. Do you know a way to assign a GPU per Camera (or per targetDisplay) in a single Unity instance ? This should be the ultimate solution for multi-display rendering (CAVE system for example) using only one computer. Thanks
     
  8. Tautvydas-Zilys

    Tautvydas-Zilys

    Unity Technologies

    Joined:
    Jul 25, 2013
    Posts:
    7,693
    There no way you can do that in Unity right now.
     
  9. ali-but

    ali-but

    Joined:
    Apr 3, 2018
    Posts:
    19
  10. Tautvydas-Zilys

    Tautvydas-Zilys

    Unity Technologies

    Joined:
    Jul 25, 2013
    Posts:
    7,693
    It will allow you to select which GPU you want the game to run on, but you can't use different GPUs per camera.
     
unityunity