Meltdown/PTI Mitigation Impact On BSDs vs. Linux

Besides the fresh BSD/Linux disk performance tests, some other tests I ran on various BSDs and Linux distributions this week was looking at the performance impact of Intel Meltdown CPU vulnerability mitigation on each of them, namely the performance impact of using kernel page-table isolation.

On DragonFlyBSD 5.2, TrueOS 18.03, Ubuntu 16.04, Ubuntu 18.04, and Clear Linux I ran tests when the mitigation was enabled and then again when it was off for seeing the performance impact.

The tests were all done on the same hardware throughout the entire testing process and each OS tested out-of-the-box besides toggling its Meltdown mitigation. Benchmarks on Linux and BSD done via the Phoronix Test Suite.

These numbers are being put out for reference purposes, so make use of them as you wish. Spectre mitigations were not toggled as part of this round of testing but just looking at a Meltdown comparison today.