16.04 - Is it possible to speed up kernel boot time?

Question

I am working on trying to get my boot up time as short as possible. I have done several changes that got my time from 3 minutes down to about 14 seconds. All of the changes seem to affect the userspace startup portion. The one thing that I noticed remains constant is the kernel startup speed. systemd-analyze gives me the following results:

Startup finished in 11.162s (kernel) + 3.239s (userspace) = 14.402s

I have tried setting GRUB_TIMEOUT=1 in /etc/default/grub but that did not influence the startup time for the kernel.

I am running 16.04 on a Lenovo U510 with a 1TB hybrid drive, no other OS on board. Thanks!

Solution

You can trim down the initramfs to speed up boot by editing /etc/initramfs-tools/initramfs.conf and setting MODULES=dep.

Then run the following to update the initramfs to hopefully make a smaller one:

sudo update-initramfs -u

Comments

[j0h]

Some linux distros are better for this. Gentoo for example. Load fewer modules on boot, and boot time should decrease. grub doesn't have much to do with the kernel. perhaps migrate this to Unix & linux SE

[Panther]

The only way is to build your own kernel . The benefits will be modest at best.

[Fabby]

14 seconds is great! Congrats! Don't change anything!

[glen abdelnoor]

Thanks, always looking to improve though, kind of the Millennium Falcon approach; keep tweaking it until I break/learn something.

[glen abdelnoor]

That seemed to work! My new startup numbers are Startup finished in 10.685s (kernel) + 2.321s (userspace) = 13.006s When I did the update I had to add "-u" to the end for it to work, so sudo update-initramfs -u , do you know why that is?

[Colin Ian King]

Sorry, my instructions were wrong, you do need a -u to trigger the update. I'll update the instructions. My bad.