A Look At The Meltdown Performance Impact With DragonFlyBSD 5.2

Besides looking at the HAMMER2 performance in DragonFlyBSD 5.2, another prominent change with this new BSD operating system release is the Spectre and Meltdown mitigations being shipped. In this article are some tests looking at the performance cost of DragonFlyBSD 5.2 for mitigating the Meltdown Intel CPU vulnerability.

With DragonFlyBSD 5.2 there is the machdep.meltdown_mitigation sysctl for checking on the Meltdown mitigation presence and toggling it. Back in January we ran some tests of DragonFlyBSD's Meltdown mitigation using the page table isolation approach while now testing was done using the DragonFlyBSD 5.2 stable release.

This round of weekend benchmarking was looking at the impact with/without Meltdown mitigation using an Intel Xeon E3-1280 v5 Skylake workstation.

Benchmarking, as always, was done by the Phoronix Test Suite.
















With tests relying upon heavy I/O or kernel interactivity, the impact is quite apparent as we have already shown from extensive testing on Linux and Windows. A Linux vs. BSD vs. Windows comparison will be coming up soon looking at the relative difference on each platform.