Ubuntu Boot Times From Linux 4.6 To 4.15 Kernels

Written by Michael Larabel in Linux Kernel on 21 November 2017 at 06:25 AM EST. 27 Comments
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.
Linux Kernel Boot Time On Ubuntu

The Phoronix Test Suite was reading the boot timings via systemd.
Linux Kernel Boot Time On Ubuntu

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.
Linux Kernel Boot Time On Ubuntu

And a look at the kernel portion of the boot process.
Linux Kernel Boot Time On Ubuntu

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.
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About The Author
Michael Larabel

Michael Larabel is the principal author of Phoronix.com and founded the site in 2004 with a focus on enriching the Linux hardware experience. Michael has written more than 20,000 articles covering the state of Linux hardware support, Linux performance, graphics drivers, and other topics. Michael is also the lead developer of the Phoronix Test Suite, Phoromatic, and OpenBenchmarking.org automated benchmarking software. He can be followed via Twitter, LinkedIn, or contacted via MichaelLarabel.com.

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