> > However, I would have expected that VLC would produce a lot
> > GPU/iGPU accesses even without drawing anything, because it would
> > try to use GPU decoder.
For the discrete GPU, the turned off screen requires much smaller bandwidth in 
any benchmark (reduces from 2GB/s to several KB/s). The same seems to be true 
with iGPU. Of course, there might exist some DRAM accesses originating from the 
GPU/iGPU. But the main traffic seems to fade. These assumptions are based on my 
experiments and I could be wrong.
(P.S.: VLC seems to be aware of the screen state. The rendering thread will 
stop when the screen is off (mentioned 
here:https://stackoverflow.com/q/76891645/6661026).)

> > Displaying video is also often done using GL or Xvideo - plain X is> > too 
> > slow for this.
I'm looking for a simpler solution. I'm not familiar with these Xorg-related 
concepts! It seems a bit strange that turning off screen requires so much 
effort! If `xset dpms force off` would not cause screen activation with user 
input or `xrandr --output...` wouldn't cause segfault, everything would be fine.

>edit to add: google suggests another candidate might be something
>called pin-instatPin works at the source code level. It counts source-level 
>accesses which might not reach DRAM (e.g., services by caches).

> > best
> > 
> > Vladimir Dergachev  
  

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