An update: The problem I reported in January went away on its own after a few weeks of having the problem every single day when I booted each morning. I was installing Ubuntu software updates when they became available during that time. There is something going on during boot that causes this problem.
"my speculation" is that I suspect a timing issue with the way things are initialized during boot up that leads to the problem. Some strange timing issue is occurring which causes systemd-udevd to fall into an infinite loop (continuously looking for something or to be notified about an action completion) and drive one of the processor cores to 100%. When a new kernel was installed or something was done to change initialization activity during boot the problem went away because the timing problem that created it was changed. I believe that some kind of race condition may be at the root of the problem. >From my earlier search on the problem symptoms, it seems that when systemd-udevd isn't working correctly you can get numerous confusing symptoms that mysteriously go away when the something changes timing conditions during boot. Since the problem is in the kernel then it effects other systems besides Ubuntu. -- You received this bug notification because you are a member of Kernel Packages, which is subscribed to bluez in Ubuntu. https://bugs.launchpad.net/bugs/1759836 Title: systemd-udevd consumes 100% of CPU Status in linux: Confirmed Status in The Ubuntu Power Consumption Project: New Status in bluez package in Ubuntu: Invalid Status in linux package in Ubuntu: Incomplete Status in systemd package in Ubuntu: Confirmed Bug description: The systemd-udevd proccess consumes 100% of a thread everytime, but i'm not noticing any difference in my computer. ProblemType: Bug DistroRelease: Ubuntu 18.04 Package: systemd 237-3ubuntu6 ProcVersionSignature: Ubuntu 4.15.0-13.14-generic 4.15.10 Uname: Linux 4.15.0-13-generic x86_64 NonfreeKernelModules: wl ApportVersion: 2.20.9-0ubuntu2 Architecture: amd64 CurrentDesktop: ubuntu:GNOME Date: Thu Mar 29 08:52:54 2018 InstallationDate: Installed on 2018-03-05 (23 days ago) InstallationMedia: Ubuntu 18.04 LTS "Bionic Beaver" - Alpha amd64 (20180304) MachineType: Dell Inc. Inspiron N5010 ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-4.15.0-13-generic root=UUID=3c29e292-f1ae-45e1-a0ed-a82524278ce1 ro quiet splash vt.handoff=1 SourcePackage: systemd SystemdDelta: [EXTENDED] /lib/systemd/system/rc-local.service → /lib/systemd/system/rc-local.service.d/debian.conf [EXTENDED] /lib/systemd/system/user@.service → /lib/systemd/system/user@.service.d/timeout.conf 2 overridden configuration files found. UpgradeStatus: No upgrade log present (probably fresh install) dmi.bios.date: 01/25/2011 dmi.bios.vendor: Dell Inc. dmi.bios.version: A12 dmi.board.name: 08R0GW dmi.board.vendor: Dell Inc. dmi.board.version: A12 dmi.chassis.type: 8 dmi.chassis.vendor: Dell Inc. dmi.chassis.version: A12 dmi.modalias: dmi:bvnDellInc.:bvrA12:bd01/25/2011:svnDellInc.:pnInspironN5010:pvrA12:rvnDellInc.:rn08R0GW:rvrA12:cvnDellInc.:ct8:cvrA12: dmi.product.name: Inspiron N5010 dmi.product.version: A12 dmi.sys.vendor: Dell Inc. To manage notifications about this bug go to: https://bugs.launchpad.net/kernel/+bug/1759836/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : firstname.lastname@example.org Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp