What happens to CPU frequency when Android downloads a large file with screen off? For example, I start downloading system update file and hit the power button to dim my screen.

What happens to CPU? Does it lowers its frequency or change its governor to powersave? Or does CPU frequency stay the same when I had screen on?
Some cases:


If it's downloading 1 file from 1 site - barely works: it's offloaded to modem.
If it's downloading via torrent - might work harder; decrypting, hashing, etc.


Basically, downloading takes little CPU.

I assume the reason you're asking this is because "Why does downloading eat my battery so hard?"

If that is the case, then think of your Cell (3G, 4G, etc) and WiFi as giant flashlights that you can't see (technically, sort of what a transmitter is). Network connections at high speed need:


High power
High frequencies
Many other math'thy thingers I shall spare you