Linux routing lookup performance regresses from SRSO mitigations on AMD

An analysis of Linux routing table performance from version 2.6.32 through 7.3 reveals that IPv4 and IPv6 route lookup speeds have been significantly impacted by CPU vulnerability mitigations, particularly Speculative Return Stack Overflow (SRSO) on AMD processors. The author demonstrates that disabling these mitigations or reordering pointer checks in specific kernel functions can recover dozens of CPU cycles, while overall IPv4 performance continues to decline slowly over time. Open article →