Kernel Performance – Fix Long Kernel Load Time in Ubuntu 18.04

18.04bootkernelperformancesystemd

Running Ubuntu 18.04 on a Dell XPS 9370, I'm getting kernel load times of over 30 seconds.

systemd-analyze output:

Startup finished in 12.834s (firmware) + 1.331s (loader) + 33.643s (kernel) + 11.692s (userspace) = 59.502s

systemd-analyze blame only shows userspace load times, so I wont include it here.

Relevant dmesg output:

[    5.154052] pcieport 0000:04:00.0: Refused to change power state, currently in D3
[    5.155956] pci_bus 0000:05: busn_res: [bus 05] is released
[    5.156127] pci_bus 0000:06: busn_res: [bus 06-38] is released
[    5.156235] pci_bus 0000:39: busn_res: [bus 39] is released
[    5.156300] pci_bus 0000:3a: busn_res: [bus 3a-6d] is released
[    5.156352] pci_bus 0000:04: busn_res: [bus 04-6d] is released
[   33.556238] EXT4-fs (dm-0): mounted filesystem with ordered data mode. Opts: (null)

Full dmesg output: https://pastebin.com/0JmWuLtZ

I've tried editing /etc/initramfs-tools/conf.d/resume as described here and adding noresume to my GRUB_CMDLINE_LINUX_DEFAULT.

How can I troubleshoot this?

Best Answer

I had disabled Intel SpeedStep® Technology in the BIOS, which was preventing the CPU from switching power states. Enabling it brought the kernel load time to about 3 seconds.

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