On my work laptop with an SSD and no swap, I sometimes run out of memory when running RAM-expensive applications (virtual machine, etc).
When that happens, the system becomes slow (expected) but what I don't understand is why the disk usage LED lights up and stays that way until I manage to kill some tasks to free up memory. That happens every time the system runs out of memory even if there's absolutely no disk IO before that.
vmstat 1
show when the system is thrashing?