kworker eats 45% from first cpu

[deloptes <deloptes@gmail.com>]

Hi community,
I moved my system to an SSD two days ago. I applied recommendation to
use "discard" when I noticed that one kworker is using exactly 45% of the
first cpu.
I tried to find out some solution in google already, but nothing alike my
issue. It seems it is tricky to find out what exactly is using the queue
and causing the higher load.

Has someone of you dealt with this problem, or have some useful idea how to
debug it?

The kernel is (i just build and installed) 4.9.1 with jessie. I also tried
using systemv init, but it is still there.

thanks in advance