I run an Ubuntu 64bit virtual machine (4 CPUs, 8Gb ram, 1Gb swap) on my Windows 8 64bit machine using virtualbox.

I often find that when I do something memory intensive (generally only using 1 or 2 CPU cores), the virtual machine will completely lock up with high disk usage reported on the host. This won't be something where the memory usage slowly increases, but rather something where memory usage expands exponentially. This seems like disk thrashing due to swapping. But given that my swap is so small compared to my RAM, surely this should just cause an out of memory error, and the OOM killer should kick in, unless I'm magically hitting a memory requirement between the physical and virtual limits every time?

Any idea whats going on or how to recover the system when this happens?

  • 1
    Have you considered just increasing the swap? 1GB swap is sort of small.
    – Ramhound
    Apr 10, 2015 at 14:18
  • 1
    How much RAM and swap does your host machine have? Apr 10, 2015 at 14:22
  • I assume your drive is NOT an ssd? Apr 10, 2015 at 14:24
  • Yeah, I tried that. The swap just dissappears almost immediately and then the freeze happens again. The host machine has 16Gb RAM, 16Gb swap. Physical memory is about 80% used when virtual machine is running. The host runs fine when the guest is frozen up. The host has a 7,200rpm spinning-disk. Apr 10, 2015 at 14:27

1 Answer 1


Press SysRq-K to run the OOM killer.

I'm not sure exactly how this works, I've been unable to find any documentation on this feature. However, the system log indicates that the OOM killer has been run, and the system becomes responsive again.

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