Comment 2 for bug 1497782

This affects me also, on upgrading a Trusty install to use the Xenial HWE stack (using both the powernap from Trusty, and the one from Xenial backported).

Traceback (most recent call last):
  File "/usr/sbin/powernapd", line 342, in <module>
    MONITORS = powernap.get_monitors()
  File "/usr/lib/python2.7/dist-packages/powernap/powernap.py", line 183, in get_monitors
    p = ConsoleMonitor.ConsoleMonitor(config)
  File "/usr/lib/python2.7/dist-packages/powernap/monitors/ConsoleMonitor.py", line 53, in __init__
    self._time, self._irqs = get_console_activity()
  File "/usr/lib/python2.7/dist-packages/powernap/monitors/ConsoleMonitor.py", line 28, in get_console_activity
    irqs = get_interrupts()
  File "/usr/lib/python2.7/dist-packages/powernap/monitors/ConsoleMonitor.py", line 42, in get_interrupts
    interrupts += int(i)
ValueError: invalid literal for int() with base 10: 'IO-APIC'

My /proc/interrupts looks like this:

           CPU0 CPU1
  0: 45 0 IO-APIC 2-edge timer
  1: 9 0 IO-APIC 1-edge i8042
  8: 0 0 IO-APIC 8-edge rtc0
  9: 0 0 IO-APIC 20-fasteoi acpi
 14: 114592 0 IO-APIC 14-edge ata_piix
 15: 114591 0 IO-APIC 15-edge ata_piix
 16: 0 0 IO-APIC 16-fasteoi uhci_hcd:usb2
 17: 48960 36725 IO-APIC 17-fasteoi firewire_ohci, eth0
 18: 12777984 12975175 IO-APIC 18-fasteoi uhci_hcd:usb4, 0000:02:02.0
 19: 0 0 IO-APIC 19-fasteoi uhci_hcd:usb3
 23: 0 0 IO-APIC 23-fasteoi ehci_hcd:usb1
...
(other lines not containing "IO-APIC")