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

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.