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Neil Bothwick spends most of his time correcting the editor.

Q  Unresolved issue

After a reboot, my trusty Lenovo W510 will be idle on all cores to the tune of 98 per cent. Temperature of the CPU will rest between 40 and 50°C. I’ll browse the internet, and perhaps open my Hotmail account and all remains well, until something triggers the systemdresolved to decide that it needs to take over the CPU, drive usage to 100 per cent CPU, and the temperature up to 80°C. I have tried to do the sudo kill -9 pid for systemd-resolved, which restores CPU availability and drops the temperature, but that leaves me without DNS services.

I have scoured the askubuntu archives for clues – they blame dnsmasq  competing with systemd-resolved in the few articles I have found. But I don’t have dnsmasq as a victim to blame. On my machine, systemd-resolved seems to have a hissy-fit all by itself. All that has to happen is that I be actively using the internet with browsers or Thunderbird.

I had long delayed update to 18.04 LTS to avoid this kind of issue, on the theory that by the time I update, most of these kinds of issues would have been long gone. No such luck.

Karl Hallin

A Using kill -9 is a severe option, and it would be better to try a clean restart first with the following:

The dnsmasq conflict does seem to be the most common cause of this situation, but it’s a specific example of a more general issue. The problem is generally caused by a program rewriting /etc/ resolv.conf. If you check immediately after booting your system, you should find that resolv.conf contains nameserver 127.0.0.53

This is pointing to the systemd resolver. What can happen is that another program modifies this file, which can cause systemd-resolved to go into a loop until all your CPU cycles are consumed. You can check this by looking at the contents of resolv.conf after the symptoms start.

If this is the case, you can fix it by modifying the configuration of resolvconf. To do so, create the file /etc/resolvconf/ interface-order containing one line: wlan*

This assumes your system is using the “old” style of interface naming. You can check the name in use by running