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Thread: RAM available - half of it lost?

  1. #1
    Join Date
    May 2014
    Beans
    20

    RAM available - half of it lost?

    Hello everybody,

    at my machine, there is 12 GB of physical RAM installed.
    Code:
    sudo dmidecode -t17
    displays the 4 bars - 2x2, and 2x4GB.

    Now, when I do a
    Code:
    $ free -m
    , look into
    Code:
    top
    or into gnome-control-center, I find that only 5,8GB of RAM are available. Which info is correct? - Do I actually loose half of my RAM?

    Cheers,
    Wolf

  2. #2
    Join Date
    Nov 2011
    Location
    /dev/root
    Beans
    Hidden!

    Re: RAM available - half of it lost?

    Please tell us which version of Ubuntu you are running (for example 18.04.x LTS) and which architecture (32-bit alias i386 or 64-bit alias amd64).

    If 32-bit, there are issues to manage big RAM. In that case please consider installing a 64-bit version of Ubuntu.

    Otherwise there could be other problems, for example related to hardware. Does the UEFI/BIOS system see all memory? Have you tested the memory with memtest?

  3. #3
    Join Date
    Jun 2009
    Location
    SW Forida
    Beans
    Hidden!
    Distro
    Ubuntu

    Re: RAM available - half of it lost?

    Linux uses RAM as a cache to reload some app you recently used.

    Linux ate my RAM! - memory use cache
    http://www.linuxatemyram.com/
    Difference between Details screen on RAM and free command
    http://askubuntu.com/questions/74364...1106622_743649 &
    https://askubuntu.com/questions/1842.../184221#184221
    For more info on UEFI boot install & repair - Regularly Updated :
    http://ubuntuforums.org/showthread.php?t=2147295
    Please use Thread Tools above first post to change to [Solved] when/if answered completely.

  4. #4
    Join Date
    Mar 2010
    Location
    Squidbilly-Land
    Beans
    Hidden!
    Distro
    Ubuntu Mate 16.04 Xenial Xerus

    Re: RAM available - half of it lost?

    And actually showing the output from the commands would be nice. Or do we need our secret-squirrel crypto-authentication rings first?

    Besides buffers, integrated GPUs will grab some amount of RAM.
    Code:
    $ head /proc/meminfo 
    MemTotal:        8048236 kB
    MemFree:          604768 kB
    MemAvailable:    3913008 kB
    Code:
    $ inxi -b
    ....
    Info:      Processes: 343 Uptime: 5 days Memory: 3462.9/7859.6MB
    Code:
    $ free -hm
                  total        used        free      shared  buff/cache   available
    Mem:           7.7G        2.9G        682M        523M        4.1G        3.8G
    Swap:          4.5G         17M        4.4G
    ....
    Code:
    $ top -b
    top - 12:33:40 up 5 days, 17:35,  3 users,  load average: 0.36, 0.42, 0.52
    Tasks: 343 total,   1 running, 246 sleeping,   0 stopped,   0 zombie
    %Cpu(s):  9.6 us,  3.0 sy,  0.0 ni, 87.2 id,  0.0 wa,  0.0 hi,  0.2 si,  0.0 st
    KiB Mem :  8048236 total,   686920 free,  3046452 used,  4314864 buff/cache
    KiB Swap:  4673532 total,  4655392 free,    18140 used.  3994300 avail Mem
    Code:
    $ sudo lshw -class memory
      *-memory                
           description: System memory
           physical id: 0
           size: 7859MiB
    So, what happened to my RAM? The iGPU ... ?
    Code:
    $ lspci -vk |perl -lne 'print if /VGA/ .. /^[\w]*$/'
    00:02.0 VGA compatible controller: Intel Corporation UHD Graphics 620 (rev 07) (prog-if 00 [VGA controller])
            Subsystem: ASUSTeK Computer Inc. Device 1d30
            Flags: bus master, fast devsel, latency 0, IRQ 126
            Memory at ee000000 (64-bit, non-prefetchable) [size=16M]
            Memory at d0000000 (64-bit, prefetchable) [size=256M]
            I/O ports at f000 [size=64]
            [virtual] Expansion ROM at 000c0000 [disabled] [size=128K]
            Capabilities: <access denied>
            Kernel driver in use: i915
            Kernel modules: i915
    7859 + 256 = 8115 MB Hummmm.
    1024 x 8 = 8192 MB
    Close enough for me.

    YMMV.

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