from Hacker News

Bisected: The Unfortunate Reason Linux 4.20 Is Running Slower

by rsendv on 11/16/18, 7:48 PM with 4 comments

• by craftyguy on 11/16/18, 11:49 PM

  tl;dr: The cause is the Single Thread Indirect Branch Predictors (STIBP) for cross-hyperthread Spectre mitigation on Intel processors.

  I'm not sure why Michael thinks this is a surprise, performance regressions were practically on the box with these mitigations.