if you are using PPPoE you may want to look at receive packet steering. It does not save a slow cpu, but it helps, if all cores were not used. In my testing atom C2758 with PPPoE on a gigabit connection went from 200mbit to about 600mbit including IPS.
you can check with:
“cat /sys/class/net/ppp0/queues/rx-0/rps_cpus”
response on 8 thread cpu will be something like:
0f
this is a bitmask for cpu threads, on 8 thread cpu you want to set it to ff with:
“echo ff > /sys/class/net/ppp0/queues/rx-0/rps_cpus”
now the bad thing, this has to be done everytime after the PPPoE connects/reconnects, i was too lazy to find out how to make this permanent.