High CPU usage when screen off

[Andryush1]

I have noticed, that sometimes there is high cpu usage when screen is off.
Most of the CPU time goes to kernel activity by process named "kworker"

Also lot of processes run when screen is off. Screenshots are taken just after screen was waked.

 

Is it normal? Maybe this causes high battery drain?

[Johan]

I have been checking this on another Xperia U and I would say that this is normal.