On 2014-10-30, Federico Giannici <giann...@neomedia.it> wrote: > Hi. > We noticed that in our firewall (an OpenBSD 5.5-stable amd64, demsg > follows) there are a large number of network livelocks > (kern.netlivelocks). We graphed them and noticed that they arrive even > to 2000 per minute! They are related to the amount of traffic but not in > a linear way. > > We'd like to know if this is expected and "normal" or we have to worry > about them and find what's wrong. > > The PC is a firewall with a large number of queues and up to 500 Mbps of > traffic. > Thanks. > > > > Here is the dmesg. NMFW is GENERIC (no MP) and only change is HZ=1000 > (for queues accuracy). >
This is expected if you increase HZ without changing how livelock detection works. It sets a timer every clock tick, when that timer has triggered it checks how many ticks elapsed, if >1 livelock is detected. This triggers livelock avoidance which will slow down your network traffic so yes you do want to pay attention to them. sys/net/if.c Also note, if you're graphing by calling sysctl(8) that may be locking the kernel for long enough to trigger livelock detection!
