The Current Retbleed Performance Costs With An AMD Ryzen 7 4800U
This AMD Ryzen 7 4800U round of benchmarking was carried out after the initial Retbleed patches were merged to the mainline Linux kernel this week following its public disclosure. The benchmarks were carried out in the default state with all relevant mitigations automatically applied and then repeating the run on the same software/hardware when booted with the "retbleed=off" kernel option to disable the Retbleed mitigation for the AMD Zen 2 CPU cores.
This is the current Retbleed costs as kernel developers eye possible mitigation improvements to reduce the overhead costs for both AMD and Intel CPUs. I'm also working on some other Retbleed benchmarks on AMD Zen 1 and on other hardware, including a look now at the compounded mitigation performance costs for the CPU vulnerabilities over the past four years.
The kernel context switching time continues to get much slower, the usual synthetic tests are significantly impacted, and I/O workloads, Java, RocksDB and other database systems and more are impacted from a few percent to double digit losses for Zen 2 with Retbleed.
See all of the Ryzen 7 4800U Retbleed benchmarks from this result page. If you missed it from a few days ago see the rest of my big Retbleed benchmarks while waiting on some follow-up comparisons in the days ahead.