With Ubuntu 20.04 due for release next week, here is a look at how the various CPU vulnerability mitigations compare on that latest Linux software stack when comparing the out-of-the-box mitigations for Spectre, Meltdown, and friends, compared to booting with "mitigations=off" for disabling those mitigations. The desktop tests were done with Intel and AMD processors for reference.

With Ubuntu 20.04 LTS offering a newer kernel compared to Ubuntu 18.04 LTS and various other software updates, this article is intended to provide fresh reference figures on the cost of these CPU vulnerability mitigations using this up-to-date Long Term Support Linux distribution using tests carried out in recent days on the near-final Ubuntu 20.04 Focal Fossa builds.

Besides testing both Intel and AMD systems, the spectrum of CPUs tested also included those completely exposed to the various vulnerabilities and more recent processors having some levels of hardware mitigation.

On each of the desktops, Ubuntu 20.04 was booted in its out-of-the-box configuration and then repeating the tests after booting the default kernel with "mitigations=off" for avoiding the various mitigations that can be toggled at run-time.

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The tested desktop systems included an Intel Core i3 8100, Core i5 6500, Core i5 9400F, Core i7 7700K, Core i7 8700K, Core i9 7980XE, Core i9 9900KS, and Core i9 10980XE. Due to the more limited exposure on the AMD side, there a Ryzen 7 3700X was run for reference purposes. Note that between the different desktops are other hardware differences at play in providing a broad look at the mitigation impact rather than trying to serve as just a detailed CPU mitigation comparison, so while you may be able to see some broad trends, this article isn't intended as a CPU comparison but just a high level look at the mitigation impact on Ubuntu 20.04.

Via the Phoronix Test Suite a wide range of benchmarks were carried out in looking at the mitigation impact on Ubuntu 20.04. Mitigation impact tests on Ubuntu 20.04 servers will be published on Phoronix in the days ahead. If you enjoy our daily Linux benchmarking articles, consider showing your support by joining Phoronix Premium.