Spectre Mitigation Performance Impact Benchmarks On AMD Ryzen 3700X / 3900X Against Intel
With the Sockperf test stressing the throughput performance of the kernel's socket interfaces, the mitigations caused a 20% hit to the Core i9 9900K while the Ryzen 7 3700X saw a 13% hit and the Ryzen 9 3900X a 10% hit in the default state. The Core i9 9900K still delivered better performance for this synthetic benchmark than the AMD CPUs even with Intel's greater mitigations. Interestingly though and what I alluded to in the introduction, the Ryzen 7 2700X saw a 5.5% hit and the Ryzen 9 2990WX a 6.2% hit.
In workloads like compiling the LLVM stack, there was a small but measurable difference on the tested systems.
With the Hackbench Linux kernel scheduler benchmark, the Intel CPUs have a much greater impact (sans the 7960X) and the unmitigated Core i9 9900K with no mitigations was as fast as the Ryzen 7 3700X only to become much slower with mitigations.
The Glibc performance impact of these mitigations was greater on the Intel systems, but even so their performance in these C library micro-benchmarks did still come out stronger than the tested AMD combinations.