Does using dGPU free up system memory?

Discussion in 'MacBook Pro' started by johngwheeler, Nov 19, 2014.

  1. johngwheeler macrumors 6502

    Joined:
    Dec 30, 2010
    Location:
    I come from a land down-under...
    #1
    I understand that the integrated Iris Pro GPU uses system RAM (up to 1.5GB, I think). If you force the machine to use the dGPU (via software, using an external monitor or running Windows in Bootcamp), does this then free-up the RAM that would have been used by the Iris Pro?

    Or does this video RAM stay in some "reserved" space irrespective of dGPU use?
     
  2. leman macrumors 604

    Joined:
    Oct 14, 2008
    #2
    The video drivers would usually hold a copy of the textures and other data in the system RAM, so I doubt that there are significant space savings. If course, it depends on the driver and the way the OS interacts with it.
     
  3. poiihy macrumors 68020

    poiihy

    Joined:
    Aug 22, 2014
    #3
    I don't think it would put it away, otherwise it would take a bit longer to switch to integrated.
     
  4. Freyqq macrumors 68040

    Joined:
    Dec 13, 2004
    #4
    In OSX, it is designed to be able to switch back and forth immediately. So, I wouldn't be surprised if a full copy of everything in the dGPU vram is also in the system ram. It would be neat if the iGPU could work with the dGPU's vram, but I don't think that is the case. However, bootcamp disables the iGPU completely. Windows doesn't even know it exists. So, it wouldn't use any system ram at all.
     

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