Fresh Benchmarks Of CentOS 7 On Xeon & EPYC With/Without KPTI/Retpolines

While every few weeks or so we have ended up running benchmarks of the latest Linux Git kernel to see the evolving performance impact of KPTI (Kernel Page Table Isolation) and Retpolines for Meltdown and Spectre V2 mitigation, respectively, a request came in last week from a premium supporter to see some new comparison test runs on CentOS 7 with its older 3.10-evolved kernel.

For satisfying that reader request, on the two current highest-end Intel/AMD server platforms I have available for testing (the dual Xeon Gold 6138 and EPYC 7601, both platforms kindly provided by Tyan) I ran some benchmarks using all of the latest CentOS 7 stable updates. On each system in the updated state I compared the stock/out-of-the-box performance with Spectre V2 mitigation as well as PTI (enabled on the Intel system) and then with both Spectre V2 / Meltdown mitigation techniques disabled.

Each server had CentOS 7 cleanly installed and all stable updates applied. Aside from the run with mitigations disabled, these were otherwise stock/default-configured CentOS Linux installations. It's important to keep in mind these CPUs aren't exactly comparable offerings and the storage is different between these servers, among other factors, with the purpose of this comparison not being for showing Intel vs. AMD performance per se but rather just providing a look at the mitigated versus not impact on each of these systems respectively. So take these results as you wish, just some benchmarking over the weekend for satisfying a request from a kind Phoronix Premium supporter.

Here are those numbers for those interested in the current CentOS 7 performance impact of Spectre V2 (on Intel/AMD, without IBPB) / Meltdown (on Intel) for these two server platforms using the current 3.10.0-693.21.1.el7.x86_64 kernel release derived from upstream RHEL7: