The "What If" Performance Cost To Kernel Page Table Isolation On AMD CPUs

Written by Michael Larabel in Software on 15 October 2021 at 12:00 AM EDT. Page 2 of 4. 28 Comments.

Workloads involving a lot of I/O and other kernel activity tend to show up as measurably impacted from KPTI, just as was the case when enabling KPTI on Intel for Meltdown.

Real-world I/O workloads like SQLite and KeyDB did show a measurable impact on performance to KPTI enabled.

Likewise, the networking workloads can take a measurable hit from KPTI.

The synthetic tests can at times show some more pronounced workloads, but even for real-world test cases like WireGuard networking performance having KPTI enabled on the AMD Zen 3 desktop CPU did result in noticeably slower performance.

Gaming and other graphical workloads showed little difference in the resulting FPS performance, similar to KPTI on Intel.

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