CPU#0: NMI watchdog performance counter calibration - 1184->1204 in /var/log/messages

Issue

• We see messages similar to the following in /var/log/messages:

  $ grep NMI /var/log/messages
  Nov 27 00:53:27 server kernel: : ACPI: LAPIC_NMI (acpi_id[0xff] high edge lint[0x1])
  Nov 27 00:53:27 server kernel: : CPU#0: NMI watchdog performance counter calibration - 1184->1204
  Nov 27 00:53:27 server kernel: : CPU#1: NMI watchdog performance counter calibration - 62->82
  Nov 27 00:53:27 server kernel: : CPU#2: NMI watchdog performance counter calibration - 62->82
  Nov 27 00:53:27 server kernel: : CPU#3: NMI watchdog performance counter calibration - 61->81
  Nov 27 00:53:27 server kernel: : CPU#4: NMI watchdog performance counter calibration - 61->81
  Nov 27 00:53:27 server kernel: : CPU#5: NMI watchdog performance counter calibration - 61->81
  Nov 27 00:53:27 server kernel: : CPU#6: NMI watchdog performance counter calibration - 61->81
  Nov 27 00:53:27 server kernel: : CPU#7: NMI watchdog performance counter calibration - 61->81
  Nov 27 00:53:27 server kernel: : CPU#8: NMI watchdog performance counter calibration - 61->81
  Nov 27 00:53:27 server kernel: : CPU#9: NMI watchdog performance counter calibration - 60->80
  Nov 27 00:53:27 server kernel: : CPU#10: NMI watchdog performance counter calibration - 60->80
  Nov 27 00:53:27 server kernel: : CPU#11: NMI watchdog performance counter calibration - 60->80
  Nov 27 00:53:27 server kernel: : CPU#12: NMI watchdog performance counter calibration - 60->80
  Nov 27 00:53:27 server kernel: : CPU#13: NMI watchdog performance counter calibration - 60->80
  Nov 27 00:53:27 server kernel: : CPU#14: NMI watchdog performance counter calibration - 60->80
  Nov 27 00:53:27 server kernel: : CPU#15: NMI watchdog performance counter calibration - 60->80
  Nov 27 00:53:27 server kernel: : NMI watchdog testing PASSED.
  

• What do these messages mean?

• Can they be ignored?