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Using multithreaded cores?




  • Matthias Miltenberger
    Gurobi Staff Gurobi Staff

    Hi Ralph,

    I don't fully understand your question. If your OS is configured to use only 8 cores, then there is no way to use the other cores of that machine. If you still request Gurobi to use more threads than available cores, the OS will have to juggle those threads around and in most cases, you will experience a slowdown. That's why the solver prints this warning message.

    You may need to change how Windows treats those cores/threads - as hyperthreads effectively doubling the number of physical cores or as pure physical cores without hyperthreading. This is probably a setting in your virtual machine software.

    Using more threads than cores can be necessary to reproduce a certain behavior that is dependent on this specific number of threads. This is probably the only reasonable application for increasing the threads number beyond the available cores.

    Best regards,

    First Comment
    First Question

    Yes, I realized after reading your comment (and some Googling) that I had not enabled hyperthreading in BIOS.  Once I did, Gurobi now defaults to using 8 physical cores, 16 logical processors, and 16 threads.


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