Improving Boot Time // Scientific Pineapple

Background

I started on this trend of improving my boot time. I currently use Arch Linux so this is pretty customizable. There are a couple of things you can do to improve boot times, including slimming down the kernel, changing the boot loader, and adjusting Systemd.

First, The Boot loader

The reason I started with my boot loader was because I tried to compile a custom kernel. When I created my custom kernel I started by deactivating a bunch of random modules. This left me with a non-booting kernel. In the process of trying to fix my kernel I messed up my grub install by deleting the Bios entry.

I went back to the default arch kernel and started with changing my boot loader from GRUB to EFISTUB. The reason being why do I need a boot loader when my Bios can load the kernel already. My computer doesn’t need to play a game of hot potato.

It took me a couple tries to get it setup because I was looking at the wrong docs and it wasn’t liking my UUID for the the rootfs partition. Once I got it all configured I worked with Thor to create a set of scripts to make it easier to adjust my kernel options.

This left me with an Arch install that didn’t have a boot loader. So the speed up was as expected, no GRUB prompt.

Second, Actually Trying to Optimize boot

Now that I’m really hyped to improve my Thinkpad’s’ boot time, I start investigating the causes of my boot. Let’s use this guide on the arch wiki.

$ systemd-analyze 

startup finished in 6.338s (Firmware) + 31ms (loader) + 3.627s (kernel) + 7.285s (userspace) = 17.282s total
graphical.target reached after 7.285s in userspace.

Ouch 17.282 seconds that’s rough. Let’s try to get the under 10 seconds.

So then let’s see who is causing this big slow down:

$ systemd-analyze blame | head 

5.449s apparmor.service
860ms systemd-logind.service
692ms lvm2-monitor.service
471ms dev-nvme0n1p5.device
407ms systemd-machined.service
314ms var-lib-snapd-snap-slack-12.mount
313ms var-lib-snapd-snap-core18-941.mount
299ms systemd-timesyncd.service
296ms var-lib-snapd-snap-discord-93.mount

“Uff da” AppArmor takes forever. How can I reduce that? Let’s see what the arch wiki has on AppArmor.

I try those fixes and apparmor time drops to 2.46s, which helps. I also see a lot of issues with snaps so let’s get rid of some snaps.

$ snap list 

Name               Version          Rev   Tracking  Publisher     Notes
core               16-2.39          6964  stable    canonical✓    core
core18             20190508         970   stable    canonical✓    base
discord            0.0.9            93    stable    snapcrafters  -
gtk-common-themes  0.1-16-g2287c87  1198  stable    canonical✓    -
gotop
htop               2.2.0            1168  stable    maxiberta     -
slack              3.4.2            14    stable    slack✓        classic
spelunky
gnome3-26-1604

Why do I have Gnome installed as a snap package? Let’s clean that up. snap remove spelunky gotop gnome-3-26-1604 Note, this later broke my discord snap because discord uses Gnome as a dependency.

Oops, I also forgot to install the microcode for my computer when I switched boot loaders, let’s do that real quick. I append initrd=\intel-ucode.img to my kernel args. However this does add a little bit to my boot time because we have to load another file.

$ systemd-analyze blame | head 

1.049s apparmor.service
860ms systemd-logind.service
692ms lvm2-monitor.service


$ systemd-analyze

Startup finished in 6.319s (firmware) + 27ms (loader) + 2.085s (kernel) + 2.564s (userspace) = 10.997s
graphical.target reached after 2.560s in userspace

That’s better but still not under 10s.

Third, Quieting the Boot

The next step without compiling my own kernel (since that went so well last time), is to silent the boot process. This also speeds up boot and it looks cooler.

So let’s append some options to the kernel args: quiet loglevel=2 rd.systemd.show_status=auto udev.log_priority=3 i915.fastboot=1

This doesn’t really do much to reduce the boot up messages. Just removed some of the basic kernel messages at startup.

Now we are going to hide fsck output. Hmm this helped with the kernel messages but not with the boot time.

Let’s try piping the output to another tty session. We need to append console=tty12 to the kernel args. This finally removed all the Systemd messages but I don’t know if it helped speed things up.

Results

I learned a lot about boot loaders and the process the system goes through from the firmware loading the kernel to the login screen showing up. I learned how to compile the kernel. I learned the purpose of the initrd file.

I reduced my boot time from 17 seconds to 11 seconds. Now when I start my machine I get the Lenovo logo then SDDM login. There’s no flurry of text as the machine starts up.

Startup finished in 6.293s (firmware) + 47ms (loader) + 1.559s (kernel) + 631ms (initrd) + 2.549s (userspace) = 11.081s
graphical.target reached after 2.548s in userspace

I plan to continue my adventure by trying 2 more things.

Doing a clean Arch install to get a baseline of boot times with Arch. It looks like Snapd adds time so I imagine that will help.
Compile a slimmed down Linux kernel and initrd.