Howto display the number of processors in Linux

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Aug 242007
 

    If you've just bought a new desktop,laptop or server and the box says the box is powered by 2 processors, you can actually verify that.

    Here's how to display the number of processor of your linux box.

    Simply issue the following command as root

    # cat /proc/cpuinfo | grep processor

    Everything in linux is files. This command simply retrieves the number of processors that linux detected from /proc/cpuinfo and displays it. Usually, the processor number comes at the first set of line from issuing the command.

    Here's what the command returned for me:
    ~~~~~~~~~~~~~~~~~~~~~~~~
    processor : 0
    ~~~~~~~~~~~~~~~~~~~~~~~~

    which means You have 1 processor with a processor ID number 0. Processor counting starts with 0.
    So if you have a PC with core duo, you will probably have 2 lines that says 0 and 1.That is 2 processors.

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       Posted by at 7:04 am
      • Lev

        Ever heard of hyperthreading? If it’s on in the BIOS, it’ll incorrectly double the number…

      • Eddie303

        Lev: I once ate that with some proliant server, it had only one CPU, and because of HyperThreading, I thought there are 2…

      • http://none Igor

        There is a lot simpler solution. Just type ‘top’ at the command prompt and then press ’1′ (number one).
        You will see the ACTUAL CPUs listed on the top of the page

      • Bubax

        > Simply issue the following command as root

        *Not* as root, because:
        # ls -l /proc/cpuinfo
        -r–r–r– 1 root root 0 2007-09-03 15:49 /proc/cpuinfo

        (Unless your system uses other permissions than mine, but I don’t see why it should do that.)

        Misuse of cat:
        > # cat /proc/cpuinfo | grep processor

        Simply use:
        # grep processor /proc/cpuinfo

      • Bubax

        Your script is broken:

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        Thank you. Your comment has been approved.

      • Randall

        If your kernel does not have SMP support compiled in, `cat /proc/cpuinfo` will only show one processor, even if you have more than one cpu.

      • cbn

        you say: how to display the _number_ :)
        $ grep -c processor /proc/cpuinfo
        2

      • http://www.hostvelocity.com Tracy Phillips

        You can run the command below and you will see number of physical processors in the server:

        [server][root][~]# grep "^physical is" /proc/cpuinfo | awk '{print $NF}' | uniq | wc -l
        1

        Now lets determine how many cores we have:

        [server][root][~]# cat /proc/cpuinfo | grep processor | wc -l
        4

        So from the above, we are able to determine that we have a single CPU quad core chip.

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