Network Manager gobbles CPU very frequently restarting dnsmasq in IPv6 networks

Bug #1041221 reported by dgf on 2012-08-24
8
This bug affects 1 person
Affects Status Importance Assigned to Milestone
network-manager (Ubuntu)
Undecided
Unassigned
Precise
Undecided
Unassigned

Bug Description

Hi,

this may be related to this bug:
https://bugs.launchpad.net/ubuntu/+source/network-manager/+bug/958519

I lost my IPv6 some time ago, after my router was broken. I have now my IPv6 connection running again and to set the mininum time between router advertisements to 10s to be not affected too strong from the mentioned bug. The fix to this bug was simply suppressing error messages.

But I was now curius what is happening at the network of my university, which got (at least some parts) IPv6. Here network manager eats up to 80% cpu, because it is restarting dnsmasq every second. If I disable dnsmasq in /etc/NetworkManager/NetworkManager.conf the cpu load drops to 20% to 30%. (syslog attached)

You should fix this, because this eats the battery of my laptop and ubuntu 12.04 will be used a couple of years in which IPv6 will get more and more deployed.

dgf

ProblemType: Bug
DistroRelease: Ubuntu 12.04
Package: network-manager 0.9.4.0-0ubuntu4.1
ProcVersionSignature: Ubuntu 3.2.0-29.46-generic 3.2.24
Uname: Linux 3.2.0-29-generic x86_64
ApportVersion: 2.0.1-0ubuntu12
Architecture: amd64
Date: Fri Aug 24 15:44:24 2012
InstallationMedia: Ubuntu 11.10 "Oneiric Ocelot" - Release amd64 (20111012)
IpRoute:
 default via 134.169.35.65 dev wlan0 proto static
 134.169.35.64/26 dev wlan0 proto kernel scope link src 134.169.35.124 metric 2
 169.254.0.0/16 dev wlan0 scope link metric 1000
NetworkManager.state:
 [main]
 NetworkingEnabled=true
 WirelessEnabled=true
 WWANEnabled=true
 WimaxEnabled=true
RfKill:
 0: phy0: Wireless LAN
  Soft blocked: no
  Hard blocked: no
SourcePackage: network-manager
UpgradeStatus: Upgraded to precise on 2012-02-14 (191 days ago)
nmcli-dev:
 DEVICE TYPE STATE DBUS-PATH
 wlan0 802-11-wireless connected /org/freedesktop/NetworkManager/Devices/1
 eth0 802-3-ethernet unavailable /org/freedesktop/NetworkManager/Devices/0
nmcli-nm:
 RUNNING VERSION STATE NET-ENABLED WIFI-HARDWARE WIFI WWAN-HARDWARE WWAN
 running 0.9.4.0 connected enabled enabled enabled enabled enabled

dgf (dgf) wrote :
dgf (dgf) wrote :

here is syslog with disabled dnsmasq

dgf (dgf) wrote :

now really

Thomas Hood (jdthood) on 2012-08-30
summary: - Network Manager consumes a lot of CPU in IPv6 networks
+ Network Manager gobbles CPU very frequently restarting dnsmasq in IPv6
+ networks
dgf (dgf) wrote :

In my initial description of this bug, I said that cpu load without running dnsmasq is 20% to 30% in IPv6 networks. Let be me clear, because you changed the summary. This cpu load is network manager alone on a Intel core i7 2.7GHz dual core cpu. In my world it should be ~0% all the time.

dgf (dgf) wrote :

It's not the same issue.

This bugs needs a bit more triaging to find the original report for this issue for Precise; and it's fix released in Quantal (12.10).

Changed in network-manager (Ubuntu):
status: New → Fix Released
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