Following Retbleed, The Combined CPU Security Mitigation Impact For AMD Zen 2 / Ryzen 9 3950X

Aside from Linux server workloads, there are plenty of Linux desktop applications also recording a difference from these various CPU security mitigation levels on the AMD Ryzen 9 3950X.

The web browser performance is one area that continues to record slower performance from these increasing CPU security mitigations.

Those wishing to go through the dozens of benchmarks in full that I ran can find them via this result page.

When taking the geometric mean of all the benchmarks conducted, the default/out-of-the-box mitigations on the AMD Ryzen 9 3950X saw the system running at 94.6% the unmitigated performance with the run-time disabling via mitigations=off. But more pressing is if using the newer retbleed=ibpb option for issuing Indirect Branch Prediction Barriers as the safest over the untrained return thunks mitigation but with the highest performance impact. Running with Retbleed IBPB mitigations yielded just 75% the completely unmitigated performance or a 20% hit over the default (untrained return thunks) Retbleed mitigated mode.

Thankfully at least AMD Zen 3 and newer do not need Retbleed mitigations and that the overall default mitigated impact is quite small.