turn off unused GPU on the laptop

By | January 2, 2018

Lots of us have dual graphics cards in the laptops these days, but almost everyone I know tends to use one or the other, hardly ever switching on the fly, since typical usage patterns tend to stick for periods of time.

One thing that almost no one seems to do however is turn off the unusued gpu – when on the move, this can have a significant impact on your battery life.

On CentOS Linux 7, the way to do this would be something like this :

echo ‘OFF’ > /sys/kernel/debug/vgaswitcheroo/switch

And thats it, lterally send it the OFF and the unused gpu is powered down.

You can also querry the interface as follows:

# cat /sys/kernel/debug/vgaswitcheroo/switch

On my Thinkpad T460p it looks like this :

0:IGD:+:Pwr:0000:00:02.0
1:DIS: :DynOff:0000:02:00.0

For more info on the vgaswitcheroo, take a look at your kernel document eg https://www.kernel.org/doc/html/v4.10/gpu/vga-switcheroo.html

Enjoy!

2 thoughts on “turn off unused GPU on the laptop

  1. Thorsten Leemhuis

    Does “OFF” save more power than the default “DynOff” (which iirc switched the Chip off until you use it with something like “DRI_PRIME=1 glxgears”? Or IOW: Why fiddle with this?

    1. Karanbir Singh Post author

      Hi Thorsten, I get the DynOff state after sending it an OFF. By default, I dont see the interface in that mode, it seems to remain in Pwr state.

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