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Linux 4.20 is Running Slower Than 4.19 On Intel CPUs (phoronix.com)

Posted by msmash on from the closer-look dept.

Freshly Exhumed writes: An intentional kernel change in Linux kernel 4.20 for enhanced Spectre mitigation is unfortunately causing Intel Linux performance to be much slower than with 4.19. That change is 'STIBP' (Single Thread Indirect Branch Predictors), which allows for preventing cross-hyperthread control of decisions that are made by indirect branch predictors. It affects Intel systems that have up-to-date microcode and CPU Hyper Threading enabled. Phoronix gives the evidence.

5 of 137 comments (clear)

  1. Give it a break by medv4380 · · Score: 5, Funny

    It's just high.

  2. Four Twenty? by Esion+Modnar · · Score: 5, Funny

    There's a joke here somewhere. If I weren't so stoned...

    --

    They say the first thing to go is your penis. Well, it's either that or your brain. I forget which...
  3. This is intels problem by Shaitan · · Score: 5, Insightful

    Linux kernel doesn't let your insecure and sloppy design do things that compromise the security of the OS. Sounds like a feature to me.

  4. Solution is simple by GerryGilmore · · Score: 5, Interesting

    You can easily disable this patch with a boot command-line argument. Unless you are running a heavily VM-ed data center with shit for security, why would you cripple your system over the most esoteric hacks known to man and that - Oh! By the way! - require that you are running malware on your system already? (And spare me the horseshit about JS - that can ONLY happen in a carefully crafted environment.)

    1. Re:Solution is simple by Mysticalfruit · · Score: 5, Informative

      Add this to your kernel boot line:

      pti=off spectre_v2=off l1tf=off nospec_store_bypass_disable no_stf_barrier

      --
      Yes Francis, the world has gone crazy.