Ubuntu 18.04 systemd-udevd uses high CPU, conflict with wifi

Solution 1:

Here's a workaround:

Immediately after booting, run the following commands:

sudo systemctl stop systemd-udevd systemd-udevd-kernel.socket systemd-udevd-control.socket
sudo systemctl start systemd-udevd systemd-udevd-kernel.socket systemd-udevd-control.socket

It worked on my Dell laptop.

Solution 2:

I installed Ubuntu 18.04 LTS (AMD64) on my Dell XPS Studio 1340 and I was suffering the same issue. I've solved it by completely disabling Bluetooth from the BIOS. I know it isn't a solution but a workaround, but it works for me because I rarely use Bluetooth.

It looks like a bug in the kernel or systemd without a fix yet:

• Bug report thread on bugzilla.kernel.org
• Bug report on Launchpad

Solution 3:

I think I've figured out the answer.

Run

/lib/systemd/systemd-udevd -D

should print garbage in endless loop containing ".../97-hid2hci.rules:"

If so, edit /lib/udev/rules.d/97-hid2hci.rules

and add

ACTION=="add" 

in front of line mentioned by above command.

It should be something like this (I'm using fedora 28, but the problem looked identical):

ACTION=="add", ATTR{bInterfaceClass}=="03", ATTR{bInterfaceSubClass}=="01", ATTR{bInterfaceProtocol}=="02", \
  ATTRS{bDeviceClass}=="00", ATTRS{idVendor}=="413c", ATTRS{bmAttributes}=="e0", \
  RUN+="hid2hci --method=dell --devpath=%p", ENV{HID2HCI_SWITCH}="1"

With above fix, everything works perfect on my old Dell. Hope that helps ;)

Solution 4:

As stated already in the previous answers, it's related to not the best one Dell Wireless 370 Bluetooth and I've been also affected by it with my Dell Studio XPS 1645.

Not only the bluetooth support has worked badly for a couple of years, now there is that new problem in kernel drivers affecting CPU usage.

I would just add that instead of removing /lib/udev/rules.d/97-hid2hci.rules file it's better to create an empty file instead:

touch /etc/udev/rules.d/97-hid2hci.rules

That will guarantee the issue not to reappear after bluez package update.

On a side note, I've finished with buying a bluetooth dongle for a pound or two on ebay but I'd rather have the laptop working as expected, of course.