An Early Look At The Linux 4.16 Kernel Performance With AMD EPYC
Overall, the performance of Linux 4.14 to 4.16 for most I/O workloads is a relatively small drop.
The AMD compiler performance isn't degraded with their Spectre mitigation techniques.
At least when running PostgreSQL with one thread, the performance hit is small. PostgreSQL couldn't run on EPYC with more threads due to a stability issue in that configuration.