[Bug 276138] [NEW] [intrepid] KNetworkManager causes ~20 wakeups/second

[Stefan Fleiter]

Public bug reported:

Binary package hint: knetworkmanager

Using powertop I found out that knetworkmanager causes from 15 to 20 wakeups per second.
That is far too much for normal operations.
These 20 still occur if wlan is deactivated by hardware switch while knetworkmanager is running.
If wlan is deactivated before knetworkmanager is started the wakeups do not occur but wlan promptly
starts to work.
So the wakeups are not necessary, at least not, if wlan is not active.

Using strace (log attached) once can see
- many select calls with dynamic timeouts, which are 0.1 seconds and less
- many reads returning EAGAIN (maybe read inspite select ended with timeout)
- many fstat calls

Top causes for wakeups:
[..]
   23,1% ( 17,4)   knetworkmanager : schedule_timeout (process_timeout)
[..]

This does seriously decrease battery lifetime and is so quite bad for
laptop users.

** Affects: knetworkmanager (Ubuntu)
     Importance: Undecided
         Status: New

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[intrepid] KNetworkManager causes ~20 wakeups/second
https://bugs.launchpad.net/bugs/276138
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