What would be good virtual memory size for Parallella?

[nis]

[sebraa]

If you cannot allocate any more memory, then you are probably out of memory.

Try to add some swap space (run "dd if=/dev/zero of=swapfile bs=1M count=NN ; mkswap swapfile ; swapon swapfile" as root, and replace NN with the desired size). Beware, SD cards are not designed for swapping, and using swap space instead of real memory makes things slow.