The Current Intel Coffee Lake Mitigation Performance Impact With Linux 5.9

Written by Michael Larabel in Software on 9 October 2020. Page 4 of 4. 12 Comments

In the end across the dozens of workloads tested, the default kernel with the relevant mitigations for this Core i9 9900K on Linux 5.9 was at 88% the unmitigated performance by simply booting the kernel with mitigations=off. For the generations affected by these vulnerabilities, it basically aligns with what we've seen from past kernels and Linux distribution releases with no big swings on a percentage basis even with recent kernel optimizations and changes in recent kernels, etc.

Fortunately with newer CPUs like Comet Lake, Ice Lake, Cascade Lake, and now Tiger Lake there are the added hardware-based mitigations to lessen the mitigation costs. Fresh numbers there will be coming up soon on Linux 5.9 or possible early Linux 5.10 state depending upon what all is queued up over the merge window opening soon. I will also have a fresh CPU cross-generation comparison once getting my hands on Tigerlake for seeing any overhead on the very newest Intel processors.

All the data for this testing can be looked at in more detail via

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Michael Larabel

Michael Larabel is the principal author of 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 automated benchmarking software. He can be followed via Twitter, LinkedIn, or contacted via