Phone performance

[Daniel van Vugt]

Hi all,

In testing performance optimisations on various phones, I keep running 
into an annoying hurdle.

Although you can optimise your Mir server/clients in such a way that 
they're smoother more often, there's an additional variable outside of 
Mir and Unity that gets in the way. That seems to be frequency scaling 
done by the kernel. Sometimes on desktops too, but I'm mostly concerned 
about phones here.

I find it suspicious that on some devices you can turn stuttering into 
smoothness just but touching the screen a lot. But the smoothness soon 
goes away when you're not touching the screen. In the extreme case, if 
you're logged into the phone remotely you will also notice the system 
can become unusably slow when the screen has turned off. That's useful 
for a real phone's battery life, but it serves to illustrate that the 
kernel is doing a lot behind the scenes. I'm more concerned about how 
can we keep phone graphics performing as well as they do during touches, 
even when we're not touching them?

- Daniel