High NIC usage (maybe WDS related?)


I've got a WDS setup with two routers running OpenWrt 18.06. One router is Linksys WRT1900ACS v1, the other is v2.

When I ssh into each router and run "top" I notice that NIC is permanently hovering between 90% to 100% but there isn't much/any real traffic going on between wireless peers. Is this normal or is my WDS setup screwed up?

I've got STP enabled on the LAN interface for both routers.


I think that you may have done two mistakes:

  • nic does not mean the network, but "nice"
  • BusyBox top output can be a bit unclear, so are you sure that it is not 90% "idle" instead. Columns can be mixed easily

I think you're right. I'm seeing:

CPU: 3% usr 3% sys 0% nic 92% idle 0% io 0% irq 0% sirq

I assumed "CPU" was a field but looking again I guess it is not. So you're saying the router is 92% idle? Okay, so a follow-up question: why do I sometimes see a very high load average (e.g. 5.2) but nothing is going on in "top"?

Or put another way: if the load average is high, how do I track it down to the source?


just run top again and watch the %CPU column and see what command/process is responsible for the load.

1 Like

Look at the 'io' percent: That's the number of i/o wait states and even only a few percent can really bump the load for applications that are i/op bound.