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Thread: CPU usage over 100%

  1. #1
    Join Date
    Aug 2008
    Location
    Mexico and Sweden
    Posts
    1,272

    Default CPU usage over 100%

    Could someone please explain how CPU usage can exceed 100% as indicated by "top" below?
    Code:
      PID USER      PR  NI    VIRT    RES    SHR S  %CPU  %MEM     TIME+ COMMAND                            
     2271 ion       20   0 2843084  75156  21080 S 117.6 1.853   0:27.53 Vcc.exe                            
     1177 root      20   0  235552  55072  14140 S 7.310 1.358   1:23.32 Xorg                               
     1417 ion        9 -11  584436  14364  11528 S 5.316 0.354   1:35.89 pulseaudio                         
     2274 ion       20   0   17640   7648    644 S 2.658 0.189   0:00.71 wineserver
    Thanks in advance.

  2. #2
    Join Date
    May 2012
    Location
    Finland
    Posts
    2,002

    Default Re: CPU usage over 100%

    You have more than 1 core in the system and the application has multi-core support - top shows each core as 100%.

    Example;
    You have 8 cores and your application has proper parallel support - it has 4 threads that are using maximum available calculation power, thus your application shows up as using 400% of CPU (out of 800% available)

    Here's an example of lbzip2 compressing a file with 4 threads in use (-n 4) on an 8-core system:
    .: miuku #suse @ irc.freenode.net
    :: miuku@opensuse.org

    .: h​ttps://download.opensuse.org/repositories/home:/Miuku/

  3. #3
    Join Date
    Aug 2008
    Location
    Mexico and Sweden
    Posts
    1,272

    Default Re: CPU usage over 100%

    Quote Originally Posted by Miuku View Post
    You have more than 1 core in the system and the application has multi-core support - top shows each core as 100%.

    Example;
    You have 8 cores and your application has proper parallel support - it has 4 threads that are using maximum available calculation power, thus your application shows up as using 400% of CPU (out of 800% available)

    Here's an example of lbzip2 compressing a file with 4 threads in use (-n 4) on an 8-core system:
    Thanks for the clear explanation. I am so far behind the times that I have a two core processor and didn't know it.

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