Can someone more experienced than me explain if CONFIG_HZ (set during kernel config) should be higher than the default 250Hz when running as an x86_64 router with Cake SQM?
I've read that higher Hz setting is for lower latency at the expense of throughput. I've also read that Hz setting only affects userland process responsiveness but doesn't affect kernel processes?
You're likely to see very little not no difference, there was much discussion to even bump it to the default 250Hz instead of the hardset 100Hz for the majority of platforms that was enforced way back. That said, no one has ever done measurements on OpenWrt regarding it.
I tested voluntary preempt with 1000Hz config_HZ on RPi4. Default is no preempt and 100Hz. Didn't see any difference in FPS games, boot time and loading of web pages under heavy load. If there's any 10ms change then it ain't worth.