Benchmarking The Linux Mitigated Performance For Retbleed: It's Painful

For Intel 6th Gen to 8th Gen and AMD Zen 1/1+/2 processors, the mitigation costs on Linux easily show themselves when running workloads with high kernel interactivity...

For many of the I/O workloads and other areas that already have been impacted by prior speculative execution mitigations, adding Retbleed on top now by default only pushes the performance back further.

Keep in mind these tests are -only- looking at the new Retbleed mitigation overhead applied by default and not looking at the accumulated "mitigations=off" impact, that macro comparison will come in a later article.

Networking performance too can be impacted by Retbleed mitigations.

Or the WireGuard in-kernel VPN tunnel solution saw significant performance regressions now with the default mitigations on these affected CPUs.