The Peculiar State Of CPU Security Mitigation Performance On Intel Tiger Lake
The Google Chrome browser benchmarks were also now showing slower performance when disabling the still relevant mitigations.
During slower news days around the holidays I'll pick back up this investigation but long story short disabling the security mitigations on the Core i7 1165G7 Tiger Lake is actually hurting the performance on this latest Ubuntu Linux release (and the Core i7 1165G7 / Dell XPS 9310) rather than improving it as we've been used to seeing out of older processors or similar performance in the case of Ice Lake. So if you are accustomed to just always booting with "mitigations=off" for trying to squeeze out more CPU performance, with Tiger Lake it doesn't look like that will pay off any longer -- unless it's something funky going on with the current CPU microcode, the Linux kernel, or other yet to be explained behavior. Also sad are still the few test cases where still an old unmitigated Kabylake-R processor can outperform Tiger Lake. In any case will be poking more at toggling the individual mitigations still relevant and other analysis to see if there is anything more to note on this behavior with Tiger Lake.
Update: It looks like the Linux kernel may be playing a role in this behavior... Follow-up benchmarks on a later Limux kernel release are showing more expected behavior for Tiger Lake mitigated performance. Still being investigated further.
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