The Disappointing Direction Of Linux Performance From 4.16 To 5.4 Kernels

With the Linux 5.4 kernel set to be released in the next week or two, here is a look at the performance going back to the days of Linux 4.16 from early 2018. At least the Linux kernel continues picking up many new features as due to security mitigations and other factors the kernel performance continues trending lower.

With this round of Linux kernel benchmarking on Ubuntu 19.10 and with an Intel Core i9 7960X the tests were done from Linux 4.16 through Linux 5.4 Git. Linux 4.16 was as far back as the system would go while running stable with the Ubuntu 19.10 user-space components -- Linux 4.15 ran into stability issues and Linux 4.14 or older wouldn't boot properly due to systemd or other user-space conflicts. But additional article(s) will be running with an older Ubuntu LTS stack for user-space as well as similarly looking at the performance on AMD hardware too.

Linux 4.16 was released in April 2018 and as such already had the initial Spectre and Meltdown mitigations in place. Since then L1TF has come to light along with MDS, SWAPGS, and other new/improved mitigations that have hampered the performance -- the forthcoming AMD Linux kernel comparison will help clarify which kernel releases regressed due to the mitigation activity as opposed to other kernel slowdowns. Linux 4.20 was also left out of this article today due to a simple oversight during testing.

The same system was obviously used throughout testing and all kernels obtained from the Ubuntu Mainline Kernel PPA. Via the Phoronix Test Suite a wide range of tests were run.