Ubuntu Boot Times From Linux 4.6 To 4.15 Kernels

It's been a while since last doing any Linux boot speed comparisons while this morning I have some numbers to share when looking at the boot performance from the Linux 4.6 kernel through Linux 4.15 Git to see how it's changed over time,

These tests were being done using a Lenovo ThinkPad X1 Carbon notebook using a mature Intel Broadwell CPU. Linux 4.6 through 4.15 Git was chosen since that's as far back as the mainline kernel would work with this Ubuntu 17.10 user-space. Linux 4.5 and older would fail to boot.

The Phoronix Test Suite was reading the boot timings via systemd.

Even with the Linux kernel growing many hundreds of thousands of lines of code in this time, the boot speed isn't that different. Contrary to the arguments that get brought up about monolithic kernels and having all the Linux device drivers in-tree, with non-core functionality not getting enabled by default or being spun as modules, the boot times haven't really slowed down as the Linux kernel has picked up weight. In fact, these boot times from the Lenovo ThinkPad are indicating the Linux 4.15 kernel is booting slightly quicker than 4.14.

And a look at the kernel portion of the boot process.

The user-space portion of the boot process remains the longest and isn't too impacted by the kernel upgrades sans when there are any I/O improvements offered, etc.

Numbers from some desktop systems coming up as part of our just-started Linux 4.15 kernel benchmarking roundabout.