Intel i9 9900k 40% Faster in Chrome Octane Bench with mitigations=off

Interesting take away.

"It was a 12% improvement for the Core i9 9900K in affected workloads by booting with "mitigations=off" on Linux 5.3 under Ubuntu 19.10. In the case of the Ryzen 9 3900X was a 4.5% difference. Notable with this overview though is that without mitigations, the Core i9 9900K comes out just ever so slightly ahead of the Ryzen 9 3900X. rather than losing by about 6%."

It's interesting at least to consider just how much performance is degraded by these hardware bugs for certain workloads. While Octane is 1.40x, the average is 1.12x. And this is the i9 9900k, which has partial hardware mitigations, so speedup is better for older chips.

But mitigations=on doesn't even give full protection from ZombieLoad attacks.. if you want full coverage you need to disable hyper-threading, which kills performance. This caused a big debate among linux devs, but keep-HT won out.

So, disabling mitigations is not a good idea for work or critical workloads. But the chance someone compromises the average computer with one of these hardware bugs is probably the same probability that two equal UUIDs are ever generated.

PC overclockers move mountains trying to eek out half-percentage perf gains. Why not flip a flag for 12%?

I thought this was always known. Common sense even.

IIRC OpenBSD disabled SMT by default, which took away from performance, but overall secured the OS from several CPU-related vulnerabilities.