The Disappointing Direction Of Linux Performance From 4.16 To 5.4 Kernels

The Sockperf socket performance benchmark with its throughput performance has been hit hard as well with the various speculative execution mitigations. The performance on Linux 5.4 is just 68% the performance of what was found in Linux 4.16 -- which that oldest kernel tested already had Spectre/Meltdown mitigations in place so not even looking at the full impact of how the performance has changed since those high profile vulnerabilities came to light nearly three years ago.

In some workloads like HMMer the performance has improved slightly on the newer kernels.

While in other workloads, the performance has remained the same.

In some of the Java tests the performance is slower since Linux 5.0 when STIBP (Single Threaded Indirect Branch Predictors) came about with conditional RSB (return stack buffer) filling.