Hi all, So I was trying to log all traffics in the FORWARD chain with the LOG target in iptables (while I say all, it's just some VPN server/client that is used by only me, and the tests were just opening some website). I notice that the logging causes high CPU usage (so it goes up only when there are traffics). In (h)top, the usage shows up as openvpn's if the forwarding involves their tuns. Say I am forwarding from one tun to another, each of the openvpn instance will max out one core on my raspberry pi 3 b+. (And that actually slows the whole system down, like ssh/bash responsiveness, and stalls the traffic flow.) If I do not log, or log with the NFLOG target instead, their CPU usage will be less than 1%. Interestingly, the problem seems to be way less obvious if I am using it on higher end devices (like my Haswell PC, or even a raspberry pi 4). There are still "spikes" as well, but it won't make me "notice" the problem, at least not when I am just doing some trivial web browsing. Let me know how I can further help debugging, if any of you are interested in fixing this. Regards, Tom
