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CPU Strange CPU load figure

Discussion in 'Hardware' started by Shielder, 3 Apr 2014.

  1. Shielder

    Shielder Live long & prosper!

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    Hi all,

    I'm currently running a monte carlo simulation on my laptop, which has an i7-3630. I've set it up to use 4 cores (the CPU, as you may know, is quad core with HT, making a total of 8 logical cores).

    The strangeness comes when I look at the CPU load, and the total load on the CPU is 74%.

    Task manager is showing 8 core load graphs and tells me that the CPU has 4 cores and 8 logical processors, but, to my simple mind, 4 cores is only 50% of 8.

    Any idea why the system has decided to only be a 6 core machine? I did run the code with 6 threads, and that loaded up the CPU to 100%. I also ran a case with 8 threads and that was slower than the 6 thread case. This indicates, to me, that something is wrong with my CPU.

    Thanks,

    Andy

    Full spec: Scan 3XS system (bought in Jan 2013), i7-3630QM, 16GB RAM, 120GB SSD, 500GB HDD and an AMD Radeon (can't remember the GPU :blush: )
     
  2. bulldogjeff

    bulldogjeff The modding head is firmly back on.

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    I think where yoou have gone slightly wrong, is that the CPU is a 4 core with the ability to run 8 threads with hyper threading. It's not a true octocore in the same as a dedicated server chip would be. It's the the abilty to run 2 threads per core as opposed to a straight forward quad core with out hyper threading.
    What I would do is let the program make its mind up how it wants to run rather than allocating it cores. Basically if it needs 8 threads it will use them. but if not the CPU will only use what it needs and may even sit idle on one core until a background process needs to do some thing.

    In the past I have seen 1 or 2 cores idle and asked why and the simple answer is they're not needed.
     
  3. Shielder

    Shielder Live long & prosper!

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    Sorry for taking so long to get back on here. Thanks for your reply.

    The code is not that intelligent. I have to tell it how many cores to run on. Previously, if I told it to run on 4 cores, it would use 50% of the cpu, but now, that has changed. And I'm not sure why.

    Strange, unless the logic on the CPU has died...
     
  4. Thawn

    Thawn New Member

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    Is it possible that something else running in the background is causing the additional CPU usage (e.g. maxing out two more threads)?
     

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