Disabling i7 hyperthreading in Mountain Lion?

Discussion in 'OS X Mountain Lion (10.8)' started by Mac32, Nov 6, 2012.

  1. Mac32, Nov 6, 2012
    Last edited: Nov 6, 2012

    Mac32 macrumors 6502a

    Joined:
    Nov 20, 2010
    #1
    Hi!

    I have a question. Is it possible to perminantly disable hyperthreading in i7 CPUs in Mountain Lion OS X? , Until I choose to enable it again that is...
    I know Apple has removed ways to do this after Snow Leopard, but can you still to this in Instruments in Xcode when using Mountain Lion?

    I know some people will wonder why I would choose to disble HT, but that aside, is this possible? :)

    Thanks!
     
  2. BlaqkAudio macrumors 6502

    Joined:
    Jun 24, 2008
    Location:
    New York
    #2
    Option is still there in Instruments, not sure if it actually works (I'm running Xcode 4.5.2).
     
  3. Transeau macrumors 6502a

    Transeau

    Joined:
    Jan 18, 2005
    Location:
    Alta Loma, CA
    #3
    you can try this:
    Code:
    sudo nvram boot-args='cpus=4'
    But the problem is, I don't know if it disables 4 logical cores, or two physical and two logical.
     
  4. Mac32 thread starter macrumors 6502a

    Joined:
    Nov 20, 2010
    #4
    Does anyone know if disabling hyperthreading (i7 CPU) is possible in Mountain Lion? I would be great to here from something who has attempted this.
    Thanks!
     
  5. Transeau macrumors 6502a

    Transeau

    Joined:
    Jan 18, 2005
    Location:
    Alta Loma, CA
  6. Mac32 thread starter macrumors 6502a

    Joined:
    Nov 20, 2010
    #6
    Thanks, but it says multithreading.. is that the same as hyperthreading? Isn't just multithreading using several actual cores?
     
  7. twintin macrumors 6502

    Joined:
    Aug 10, 2012
    Location:
    Sweden
    #7
    Yes. HT is just the term Intel uses for the technology implementing multithreding.
     
  8. Mac32 thread starter macrumors 6502a

    Joined:
    Nov 20, 2010
    #8
    Exactly, I talking about disabling HYPERthreading, that is making the i7 CPU function as an i5 CPU. Does anyone know how this could be done? I know it's possible in Windows, but in Mountain Lion?
    Again, thanks for helping out.
     
  9. Transeau macrumors 6502a

    Transeau

    Joined:
    Jan 18, 2005
    Location:
    Alta Loma, CA
    #9
    I don't think you are understanding...

    Hardware Multithreading is the technical term for what Intel uses the marketing term Hyperthreading.

    Uncheck that box, and you will be left with 4 physical cores, and 0 logical.
     
  10. Mac32 thread starter macrumors 6502a

    Joined:
    Nov 20, 2010
    #10
    Oops, sorry about that. I think I'll go for a iMac i5 anyway. I really don't need that extra hyperthreading power, and at the same time getting a hotter and more expensive computer just isn't worth it for my uses. Thanks for the help.
     
  11. IYIOsmancik, Sep 25, 2013
    Last edited: Sep 25, 2013

    IYIOsmancik macrumors newbie

    Joined:
    Sep 25, 2013
    #11
    Hi.I'm newbie.And my problem is a little different and a little same.:) My i7's hyper threading is not working.How can i enable it? I downloaded and installed Xcode but i didnt understand anything.Where is instrument setting?

    Edit:I found instrument settings at Xcode 5 and my HT is just enabled.But Autodesk Maya 3D program uses onlt 4 core not 8.How can i fix this?
     
  12. benwiggy macrumors 68020

    Joined:
    Jun 15, 2012
    #12
    You can't fix this. If it isn't happening, then it won't work.

    As for all the people trying to "disable" HT: why? What benefit does this give you?
     
  13. Phantom Gremlin macrumors regular

    Joined:
    Feb 10, 2010
    Location:
    Tualatin, Oregon
    #13
    verify with activity monitor

    When I run Activity Monitor on my dual-core Macbook Pro, it shows 4 CPUs. Obvious conclusion is that two are real, two are just hyperthreading.

    So it should be possible to easily confirm that hyperthreading is turned off by looking at the pretty CPU window.
     
  14. MacMan988 macrumors 6502a

    Joined:
    Jul 7, 2012
    #14
    Code:
    system_profiler | grep Processor
    when I typed that command it returns a text that says "httpdEnabled is deprecated !!".

    Any idea what that means?
     

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