Hyperthreading Hurts Server Performance?


I saw this article today: Hyperthreading Hurts Server Performance?

We use lots of commodity hardware running Linux for our application servers. It would be interesting to do the Pepsi challenge and see if HT is affecting our performance…



Author: Tim...

DBA, Developer, Author, Trainer.

9 thoughts on “Hyperthreading Hurts Server Performance?”

  1. All you need is HT aware scheduler in the OS kernel.

    Suppose you have 2 physical CPU with HT. The “dumb” OS will think: “great! we have 4 CPU: 0, 1, 2, 3 to work on”.

    So it will schedule the first task on CPU 0 and the next on CPU 1. The problem here – CPU 0 and CPU 1 is the SAME physical CPU.

    The “clever” OS istead will schedule task 1 on CPU 0 and task 2 on CPU 2 – because it understands the difference between physical and logical CPUs (hence the “HT aware”).

  2. Tom: Yeah, I don’t think we’ve bought an Intel server in the last two years without it 🙂

    Quadro: What OSs have a HT aware scheduler?

    The Oracle line is that Oracle is fine an uses the extra chips as if they were real. I’m sure this is true, but there should definitely be a preference in the order and type of work that is assigned to the processors.



  3. tim: time to read specs for your OS 🙂

    At least Linux 2.6 kernel is indeed fully HT-aware (if enabled in the kernel).

  4. “The Oracle line is that Oracle is fine an uses the extra chips as if they were real.”

    The OS schedules Oracle, not the Oracle itself. So it depends solely on OS.

  5. Quadro:

    Regarding OS specs: Yep 🙂

    Regarding Oracle statement: My second sentence related to th OS, not Oracle, but I didn’t write is very clearly. So I agree 🙂



  6. Well , This is just a matter of settings. Oracle, MsSQL , MySQL etc is just a DB platform

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