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

For PostgreSQL server performance there was a noticeable impact to the out-of-the-box performance with Retbleed mitigations applied.

Unfortunately the context switching speed is far more costly now with these latest mitigations.

There was a measurable difference in performance with ClickHouse and other database workloads.

With the Nginx and Apache HTTP web servers there was also a measurable impact from the Retbleed mitigations that are now applied by default on affected CPUs. At least newer AMD and Intel CPUs aren't impacted by Retbleed, but for those affected CPU generations, the patched Linux kernel carries some measurable cost.

Those are my initial benchmarks over the past day of exploring Retbleed. I'll have more tests on affected Intel/AMD processors and exploring the total default mitigations vs. "mitigations=off" disabling coming up in future articles along with other more time consuming tests. At least the latest Intel and AMD CPUs are not affected by this vulnerability. If you enjoy my relentless Linux benchmarking, consider joining Phoronix Premium.