Logical processors

  • TomThomson (9/22/2016)


    Interesting question.

    There is a rather odd statement in the explanation: "Hyperthreading does not affect licensing limits". That's not correct. Hyperthreading doess affect licensing limits on a virtual machine, if this question had been about running on a VM instead of directly on a physical machine the limit would have been reduced from 24 logical processors (12 cores) to 16 logical processors (8 cores) since the question states that hyperthreading is switched on: so having hyperthreading would reduce the licensing limit.

    Tom...you're melting my head!!! :crying:

    But I am sure that some will find that very interesting and informative. So thanks.

    Gaz

    -- Stop your grinnin' and drop your linen...they're everywhere!!!

  • TomThomson (9/22/2016)


    Interesting question.

    There is a rather odd statement in the explanation: "Hyperthreading does not affect licensing limits". That's not correct. Hyperthreading doess affect licensing limits on a virtual machine, if this question had been about running on a VM instead of directly on a physical machine the limit would have been reduced from 24 logical processors (12 cores) to 16 logical processors (8 cores) since the question states that hyperthreading is switched on: so having hyperthreading would reduce the licensing limit.

    In the question explanation I say that the max logical processors SE can use is 16 when on VM, otherwise SE will use all logical processors (max 16 x 2 = 32). The question is for 12 physical cores.

    I also posted the query which you can run to see the visible logical processors in sql server. It lists 16 on a VM with 18 logical processors. On a 12 core physical server with hyperthreading enabled, sql server makes use of 24.

    The QotD is mine experience with dedicated physical and virtual servers.

    Licesing is ONLY per core.

    Igor Micev,My blog: www.igormicev.com

  • Igor Micev (9/22/2016)


    TomThomson (9/22/2016)


    Interesting question.

    There is a rather odd statement in the explanation: "Hyperthreading does not affect licensing limits". That's not correct. Hyperthreading doess affect licensing limits on a virtual machine, if this question had been about running on a VM instead of directly on a physical machine the limit would have been reduced from 24 logical processors (12 cores) to 16 logical processors (8 cores) since the question states that hyperthreading is switched on: so having hyperthreading would reduce the licensing limit.

    In the question explanation I say that the max logical processors SE can use is 16 when on VM, otherwise SE will use all logical processors (max 16 x 2 = 32). The question is for 12 physical cores.

    I also posted the query which you can run to see the visible logical processors in sql server. It lists 16 on a VM with 18 logical processors. On a 12 core physical server with hyperthreading enabled, sql server makes use of 24.

    The QotD is mine experience with dedicated physical and virtual servers.

    Licesing is ONLY per core.

    The page you quote in your explanation is pretty explicit, it says

    msdn.microsoft.com/en-us/library/ms143760(v=sql.120).aspx[/hr]In a virtualized environment, the compute capacity limit is based on the number of logical processors, not cores, because the processor architecture is not visible to the guest applications.

    So in a virtualized enviromment, the licensing is based on the number of logical processors.

    Your QotD specifies a physical environment and in that environment the licensing limit is indeed based on cores. So the question and the answer and most of the explanation were fine. The statement in the explanation that I regarded as "odd" looked to me as if it could be taken by some readers as a general statement for all environments, not just the physical environment specified for the server in the question (which I imagine is he environment you intended it for) so I though that it would be better if explicitly clarified to apply only in a physical environment. I guess my comment achieved the desired effect, because just over an hour after I made the comment Steve added the missing qualification, and the statement can no longer be misunderstood.

    Tom

  • TomThomson (9/22/2016)


    In a virtualized environment, the compute capacity limit is based on the number of logical processors, not cores, because the processor architecture is not visible to the guest applications.

    [/quote-2]

    So in a virtualized enviromment, the licensing is based on the number of logical processors.

    Your QotD specifies a physical environment and in that environment the licensing limit is indeed based on cores. So the question and the answer and most of the explanation were fine. The statement in the explanation that I regarded as "odd" looked to me as if it could be taken by some readers as a general statement for all environments, not just the physical environment specified for the server in the question (which I imagine is he environment you intended it for) so I though that it would be better if explicitly clarified to apply only in a physical environment. I guess my comment achieved the desired effect, because just over an hour after I made the comment Steve added the missing qualification, and the statement can no longer be misunderstood.

    You're correct. And as Steve's addition "Hyperthreading does not affect licensing limits for physical servers.", makes the question's answer complete.

    Even though the question wasn't about licensing and virtual machines, we've resolved the dilemma about it.

    And I double checked this with the hosting provider - that the licensing for virtualized environments is affected by the hyperthreading.

    Thanks Folks.

    Igor Micev,My blog: www.igormicev.com

  • Well, this one got me. I thought it was limited to 16 cores and didn't think about HT. Thanks for the question and telling me I need more caffeine to pay attention.

  • Hi

    answer section Yesterday's Question (by Igor Micev): in daily email is wrong

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