on our dual Xeon server when it reachs serveral milion pps we get very high xt_misc cpu usage on all Cores.

any idea what xt_misc is? and how to lower the usage?
thanks

"several million PPS" is quite a lot. For example: CCR 2216 (which is more or less MT's flagship device) hits its perfromance ceiling at around 2.9Mpps (when routing and firewalling with CPU ... not when L3HW offload is effective). See official test results ... see row "Routing -> 25 ip filter rules"

So I'd say you're hitting performance limit of your x86 router.

i think there is more juice if I am able to optimize it.
ethernet+routing+firewall+ice is about 25% and xt_misc alone is 30%

something not good going on.

I have the same issue; my CCR 2216 device experienced high CPU usage across almost all cores. Then, the process with high usage was xt_misc.

What is the xt_misc process? What causes it to have high CPU usage?

xt_<blah> are typically Linux netfilter modules.

xt_misc doesn't seem to appear in Linux mainline releases, but the source code for it is included in MikroTik GPL sources. It's not commented much, but as far as I can tell from a quick glance it adds some of the uniquely-MikroTik firewall/NAT/mangle matchers that are possible on RouterOS.

Are those of you seeing high xt_misc usage doing anything on your x86 routers that actually requires connection tracking? If not, I would try simply turning connection tracking off. I bet that either eliminates the xt_misc process you are seeing, or reduces its CPU consumption considerably.