APU 1D TESTING: how to fill ram enough to hangs it, or not.



  • .Hello people, I am here today to show you how you can embarrass any computer system, specifically my APU1D with 2GB RAM onboard units within 300 seconds.  8)

    What I would like to check out: Is the use of SWAP slice, of pfSense, to see if the system responds well to overload.
    My answer is NO.  ;D

    Well next I try to explain my test a little bit better.
    So, first of all I setup Ramdisk of /tmp and /var folder by filling right field and checkbox under "RAM Disk Settings" from "system">"Advanced">"Miscellaneous" tab menu.

    I enabled all and set 900MB for both. After save this changhes pfSene will force to reboot if your never enabled it first.

    Next after rebooting, the pfSense running as normal, Ram usage around 10% Cpu load is low.
    Open one terminal shell trought ssh and try to fill the /tmp ramdisk:

    [2.3.1-RELEASE][admin@pfSense.home]/root:```
    touch /tmp/overflow

    and
    [2.3.1-RELEASE][admin@pfSense.home]/root:```
    dd if=/dev/urandom of=/tmp/overflow
    

    This will fullfill your /tmp ramdisk in seconds, you also check the "Memory Usage" status in dashboard increasing when filling with dd crap, according to ramdisk size, but (this is first strange thing) the /tmp size status NOT increasing too.
    DD ends with :

    /tmp: write failed, filesystem is full
    dd: /tmp/overflow: No space left on device
    1783809+0 records in
    1783808+0 records out
    913309696 bytes transferred in 99.302361 secs (9197261 bytes/sec)

    WARNING!!
    Using the "dd" program is dangerous if you fail to enter the paths, you can mess'up your installation of pfSense, so do not take any responsibility for any damage caused to your operating system due to incorrect an usage of the information in this article .
    WARNING!!

    At this time the pfSense still it works well, so go to "brick" it now :D

    Do the same filling process to /var/run plus I start one iperf instance to check operational issue. (this also need iperf to be installed first)

    In another pc-local terminal you can start iperf server process:

    babiz@M51SE ~ $ iperf -s
    –----------------------------------------------------------
    Server listening on TCP port 5001
    TCP window size: 85.3 KByte (default)

    Next open another ssh shell to pfSense and launch iperf client
    [2.3.1-RELEASE][admin@pfSense.home]/root:```
    iperf -c [YOU_IPERF_LAN_SERVER -i 10 -t 3600[/code]

    This is enough time (-t3600 seconds) for testing lol.
    And now you go to first pfSense ssh session and type:
    [2.3.1-RELEASE][admin@pfSense.home]/root: [code]touch /var/run/overflow[/code]
    Followed by:
    [2.3.1-RELEASE][admin@pfSense.home]/root: [code]dd if=/dev/urandom of=/var/run/overflow
    [/code]

    Well after send this command you can check the "Memory Usage" status increasing until reach about 99% (on 2Gb system ram) and after about 300 seconds:

    • iperf session give up,
    • all ssh connection closed
    • all http/s connection dropped
      no way to access on pfSense until hard reboot.

    Only I see trought serial terminal interface this: (because I try to unplug and replug ethernet cable)
    [img]https://snag.gy/bstGJh.jpg[/img]

    So the second thing is strange if swap space avaible but not used by o.s. ??
    In short when ram memory is under  full load teorically the o.s. can swap portion of memory from ram to swap for freeing resource, but seems to not functional here.
    Actually I expected to see activities in swaps space, I think this not working as well.

    Ok folks! Feel free to "brick" your devices now that you have a reason to do so. Goodbye.

    The SWAP slice also still remain at 0% of use