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Thread: No multithreading on ARM CPU (python, tar..)

  1. #1
    Join Date
    Apr 2013
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    8

    No multithreading on ARM CPU (python, tar..)

    Hello, i am running Ubuntu 16.04.

    [system] Platform: linux
    [system] Arch: arm
    [system] OS Release: 4.9.160-armada375
    [system] CPU: ARMv7 Processor rev 1 (v7l)
    [system] CPU Logic cores: 2
    [system] Total memory: 2019.60 MB

    I am using htop and top to monitor CPU usage of the running processes.

    I see that my python script is utiliting like around 100% of the CPU. htop visualize only one thread fully utilized and other only sporadically utilized (probably by other processes).
    Same for tar (tr -czf) it also used only one CPU thread. I have not tested any other utilities.

    Please what i should try to change so processes utilizing multiple CPU threads? Thank you in advance.

  2. #2
    Join Date
    Mar 2010
    Location
    Squidbilly-Land
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    17,094
    Distro
    Ubuntu Mate 16.04 Xenial Xerus

    Re: No multithreading on ARM CPU (python, tar..)

    Each process is scheduled to run on a CPU.

    If you want a single process to use multiple CPUs, then you'll need to write a multi-threaded application. It is non-trivial and brings all sorts of other complexities into coding like data protection. Never allow more than 1 thread to write to the same memory or disk file without using a locking mechanism first. https://www.toptal.com/python/beginn...lism-in-python is what google found for writing multi-threaded python.

    A common way to see multi-threaded apps work is to calculate pi. Back in the 1990s, when I got my first dual-CPU computer, I also wanted to see it work. Since you don't care about the result, just seeing both cores used, https://gist.github.com/skeeto/212715

    I doubt tar is multi-threaded, since it is either reading from or writing to a file. A quick google says that libbzip2 is multi-threaded, so if you use that compression, multiple threads should be used. That would be tar cjf options according to the manpage. I didn't test it. Tar is of limited use these days. I only use tar like I would use ZIP, which is pretty much never.

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