The Combined Impact Of Retpoline + KPTI On Ubuntu Linux
Written by Michael Larabel in Ubuntu on 9 January 2018 at 05:57 PM EST. 30 Comments
UBUNTU --
Over the past week I have posted many KPTI and Retpoline benchmarks for showing the performance impact of these patches to combat the Spectre and Meltdown vulnerabilities. But with my testing so far I haven't done any showing the combined impact of KPTI+Retpoline on Ubuntu versus a completely unpatched system. Here are some of those results.

Similar to the Benchmarking Clear Linux With KPTI + Retpoline Support, these tests are similar but with a few different systems and looking at the performance when testing from Ubuntu 17.10. The comparison on each system was to a stock Linux 4.14.0 kernel compared to the Linux 4.14 kernel with the upstream KPTI patches paired with the Retpline v5 patches that have yet to be merged for mitigating Spectre.

This round of tests were on a Core i9 7980XE, E3-1280 v5, and Core i7 6800K systems.

The i7-6800K system was hit particularly hard in FIO random write workloads.

Pretty much all the same I/O and heavy kernel interactivity workloads are impaired, as illustrated over the past week, just now is a look at the combined look of going from no Spectre/Meltdown protection to having both Kernel Page Table Isolation and Retpoline.


Building out the GCC compiler becomes a bit slower.


More benchmark data from this comparison can be found via this OpenBenchmarking.org result file.
About The Author
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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 10,000 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 or contacted via MichaelLarabel.com.

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