With the massive vulnerabilities recently discovered in Intel CPUs, the main question on everyone's minds are when affected devices will be updated to guard against possible exploits. Apple is ahead of the game; apparently, the latest versions of their various operating systems protect against Meltdown, and a fix for Spectre is coming to Safari in the next few days. The best part? These mitigations have no perceptible effect on performance.
https://www.notebookcheck.net/Apple-devices-are-already-protected-against-Meltdown-without-any-hit-to-performance.276946.0.html
Given the nature of the exploit, the headline is wrong and does not match what Apple said. Geekbench and the other benchmarks they used should *not* show performance degradation in kernel with these mitigations. There will still be performance penalty for syscalls on XNU-based systems.
No performance degradation because Apple since 32-bit has always used dual page tables in order to take advantage of the full addressable memory space, therefore no performance difference with the kpti patch applied.
As expected: no loss of performance in those specifically chosen benchmarks.
But mkfile(8) throughput is reduced to 33% of pre-patch performance. Search "Meltdown mkfile(8)".