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single core usage in a multi core system

when i benchmark my i7 Q3630m on Cinebench on single core testing only I always thought that only one core runs full bore and the other cores sit idle, but when I monitor the cores frequency on TMonitor it shows all cores running at slower intermittent speeds and using Core Temp shows all cores are at the same temp. Is that how most multi core systems run a single core application or test?
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  1. Best answer
    If the CPU affinity is locked to a single core then it should only use 1 core.
    Otherwise it's core bouncing to even the workload.
  2. Cazalan said:
    If the CPU affinity is locked to a single core then it should only use 1 core.
    Otherwise it's core bouncing to even the workload.


    If there is an option to lock the cpu affinity is it more efficient to do that vs having the core bouncing
  3. Let your system balance the load. It's much more efficient and you will get more work done in the same amount of time. Why would you want to force one core to be idle? Sure, you can then force the other core to bear the full workload, but then it is most likely bottlenecking your throughput. If there's enough work to keep two cores mostly busy, then forcing all the work onto one core is clearly going to slow your total throughput.
  4. hover389 said:
    Cazalan said:
    If the CPU affinity is locked to a single core then it should only use 1 core.
    Otherwise it's core bouncing to even the workload.


    If there is an option to lock the cpu affinity is it more efficient to do that vs having the core bouncing


    In short, Yes. With CPU affinity locked that core will remain at max turbo, and the application will run at max speed.

    When a program switches cores there is a small ramp time for the new core to go from normal to max turbo. In general it's not necessary to set affinity on programs as the difference may not be very noticeable.
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