The Current Spectre / Meltdown Mitigation Overhead Benchmarks On Linux 5.0
With FIO storage benchmarks on the Intel side, it wasn't uncommon to see a 20% drop in performance or even more in some cases while generally the AMD Spectre mitigations by default just hit its I/O performance by a few percent.
With the Compile Bench I/O tests, the performance hit by default was about similar on the Core i7 8086K and Ryzen 7 2700X while the 7980XE system took a 17% performance penalty with the default mitigations.
PostMark also shows a rather sizable hit on all systems but more so on the Intel boxes needing to also mitigate for Meltdown via KPTI.
With the t-test1 memory allocator benchmarks, the Intel systems took a performance hit from their mitigations while AMD performance went unchanged. However, the Intel systems were much faster than the Ryzen 7 tested.
Sockperf also shows a sizable performance hit still from the default mitigations on Linux 5.0 but granted less on the AMD side due to not being exposed to Meltdown and its mitigations.