Ah,that never came across my mind.You're probably right.And it may also explain why the performance of shadowsocks did not increase.Thanks.
Yes it doesn't work, i should have updated this thread.
I also switched over to kernel 4.19.
(cause i wanted all the mvneta fixes, without messing around backporting them )
The cpu clk driver is a bit driver, but not much.
So the cpu clk driver isn't setting the actual cpu clock,
it is only used to map the actual hardware clock to software freq table?
The question is, is it even possible to modify the cpu freq through software?
Or is a hardware mod needed? Or must the cpu freq set during boot? (u-boot)
Without a TTL-USB cable around,I wouldn't mess with u-boot.
And speak of hardware mod,did you add a fan on the router?
I haven't messed around with the overclock/u-boot/fanmod.
I spend time some on getting kernel 4.19 and dsa to work.
Yes without ttl cable im not gonna touch u-boot 
I also haven't found a config that is guaranteed to be working, so a ttl cable is a must.
Good luck with that.
For now, I just add a fan into the chassis and call it a day.