Keeping the Screen Turned off While Getting Inputs

[Dave Howorth]

On Sat, 26 Aug 2023 20:46:35 +0100, Dave Howorth wrote:

> On Sat, 26 Aug 2023 13:43:21 -0400 (EDT), Vladimir Dergachev wrote:
> 
> > On Sat, 26 Aug 2023, Ahmad Nouralizadeh wrote:
> >   
> > > >> Those accesses might not stop with just the display off - some
> > > >> applications may keep redrawing.    
> > > Will these accesses cause iGPU or dedicated GPU accesses to the
> > > DRAM? I think that those redrawings originate from the
> > > processor.   
> > > >I'm not sure a graphical benchmark will run without a graphical
> > > >system running?    
> > > Yes, VLC is one of the benchmarks and will not run without
> > > GUI.    
> > 
> > You can start system with plain X and twm for window manager - this
> > would produce minimal load on the GPU.
> > 
> > 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.
> > 
> > Displaying video is also often done using GL or Xvideo - plain X is
> > too slow for this.
> >   
> > >     
> > > >Maybe do the reverse of what I suggested. Run the benchmark but
> > > >send the output to a remote display.    
> > > Will it avoid screen activation in the local machine?    
> > 
> > There should be a rather drastic difference in speed between VLC 
> > displaying locally and in a remote X using network.  
> 
> Indeed but speed doesn't seem to matter. Some count of particular RAM
> accesses is what seems to be important. I'm not clear exactly what RAM
> accesses nor why the count is important, nor what disturbance to the
> normal operation is permitted. Maybe instrumenting a gdb trace of the
> benchmarks would be more accurate?

edit to add: google suggests another candidate might be something
called pin-instat

> > best
> > 
> > Vladimir Dergachev