Questions about commands to limit CPU usage

Is there any code to limit the CPU usage of the computer except for 'mp omp' in the PZflex command?

Does PZflex support using 2 physical CPUs? I use 2 physical CPU for PZflex, but when I run mulitple works, it still use 1 CPU's threads and second CPU's threads are all idle.


  • OnScale will only use one thread on a Core. Can you confirm whether it's only one CPU is being used with the other idle or whether one thread is used on each cpu?

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  • When I run the PZflex, only one CPU is being used with the other idle.

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  • My computer specs are 2 CPUs and 72 threads (36 threads per CPU).
    When I check the information with the command 'ncpu' in PZflex, it says 1 socket, 72 threads.
    However, when I run the PZflex, PZflex is using only 36 threads(one CPU).
    Is there any way to make PZflex use 2 sockets when running?
    Thank you for your help.

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  • To clarify, a CPU is the physical device that goes into a socket. 1 CPU/socket. Cores are the hardware logical processors on the CPU. Threads are a virtualization of compute capability.

    You have not clarified how many cores your CPU has. Is it possible that you have 1 CPU with 36 cores and 72 threads?
    Please try the following commands.

    symb #get { ncpu } ncpu
    symb #get { ncore } ncore
    symb #msg 1
    your machine has $ncpu CPUs and $ncore Cores


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    My CPUs are both intel Xeon Gold 5220(18C36T), use 2 physical sockets for 1 motherboard. ASUS WS C621E SAGE. So, it becomes 2 socket, 36 cores, 72 threads (logical processors). And of course, I can check all of these CPU features in Windows Task manager. Also I can use 100% of it by run Prime95.

    My main problem is “PZFlex cannot use second cpu”. When I run multi works in same time, PZFlex can use 100% of fisrt CPU, equal to 18C36T. But NEVER USE second CPU, so my PC’s half of performance is wasted.

    When I put given code, ncpu and ncore, it appears 1 and 18. It seems PZFlex detect only one CPU. But debug text from mp-omp was 1 socket, 72 cores. I think this ‘cores’ mean PZFlex detect all of my PC’s threads(logical processors), BUT it still said ‘1 socket’.

    So me and my team VERY CONFUSED about this situation. Main question is “Can PZFlex 2018 use 2 physical sockets of CPU?” And if it does, how can we solve this trouble?


    In addition, when I saw debug text form command ‘mp-omp’, it said ‘number of licensed openmp threads’ value is 16. I think this is value for maximum number of threads that PZFlex use for single work. It is right?

    If its right, next question, how can I change this number? Me and my team strongly wanted to use all of my PC’s core for PZFlex, so I want to change it to 72(or differ to other PCs).

    When I put larger number than 16 in mp-omp command, the “Maximum number of processes available for job” never exceed 16, that value for ‘Number of licensed openmp threads’.


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