The "Rollover timer fired at an unexpected time" message is a warning message from the ExaNIC driver code that extends the 32 bit time provided by the ExaNIC to 64 bits, which works by setting a timer to fire when the time counter is expected to wrap around.
- If you only see this message once, then it is most likely caused by another process like NTP or PTP that has to adjust the clock by a large amount in particular, at startup.
- If you see these messages are occurring sporadically and take a bit to recover it might be another process is adjusting the clock or high system load is causing timers to get delayed.
- If you see these messages continuously and the rollover timeout is off by almost exactly the same amount every time this suggests a clock is running either too fast or too slow. Note that some Linux kernels (4.9.0, fixed in 4.14.15) used an incorrect TSC rate for Intel Skylake Xeon CPUs - if you're running one of these CPUs, you should check your kernel version. For CentOS/RHEL kernels, this was fixed in 3.10.0-862.2.3.