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Dual graphics - laptop

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  • Dual graphics - laptop

    I have an ASUS TUF laptop with AMD integrated and AMD discrete graphics. I want to know if there is a method to fully disable the discrete graphics in the laptop for power saving. or.. Maybe the discrete graphics if there is no graphic workload is almost down and off?
    I am asking because in windows I get 10 hours of battery and in Linux less than a half. I don't know the cause yet, but I don't think the problem is in the CPU..

  • #2
    The dGPU will be powered down automatically when it's not in use by runtime power management. The iGPU will dynamically powergate most blocks on the GPU when they are idle.


    • #3
      I have an asus fx505dy and even though the dgp seems disabled
      0DIS: DynOff: 0000: 01: 00.0
      1: IGD-Audio: DynOff: 0000: 05: 00.1
      2: IGD: +: Pwr: 0000: 05: 00.00 DIS: DynOff: 0000: 01: 00.0
      1: IGD-Audio: DynOff: 0000: 05: 00.1
      2: IGD: +: Pwr: 0000: 05: 00.0

      still consumes energy
      Adapter: PCI adapter
      vddgfx: 1.10 V
      edge: + 42.0 ° C (critical = + 94.0 ° C, hyst = -273.1 ° C)
      power1: 14.11 W (capacity = 48.00 W)

      I can reduce the power consumption a little bit, around 3W, using corecrtl to force use only the lowest states or even a little bit more by filtering the dgpu pci id on boot but never disabling it completely and the consumption is greater than 8-9W.


      • #4
        When you read the power from the device, the device is powered up to query that information.


        • #5
          The data are consistent with that obtained at the battery or wall outlet using a power meter.
          I have also confirmed with glmark2 and with games that the integrated card is being used and the consumption of the dgpu while playing continues to be around 10-14W.
          On windows the idle consumption is much lower so it seems that technically it is possible to deactivate it.
          thank you,


          • #6
            If you are querying the power from the dGPU regularly, it will wake the card every time you read it. It will be powered down when not in use.


            • #7
              It seems that the 5.10 kernel is going to be as good as the 5.8 for this laptop.

              [email protected]:~$ uname -a
              Linux julien 5.9.0-next-20201016 #2 SMP Sat Oct 17 05:50:20 CEST 2020 x86_64 x86_64 x86_64 GNU/Linux
              [email protected]:~$ upower -i /org/freedesktop/UPower/devices/battery_BAT0 | grep energy-rate
              energy-rate: 5,803 W

              and now fans are stopped. Silent on idle and some hour of battery for free.
              Thanks to Lukas Wunner,