OOM has trouble to KVM, it can’t shot down the kvm
In Linux, if the system is out of memory, OOM will pick one process to kill. But someone reported the OOM can’t kill the qemu-kvm, that mean if you are running many VMs that eat up all the memory, the Linux will hang because OOM can’t kill them
In tried to run 64 VMs using qemu-kvm with 1GB ram each. Without turn on the swap, the linux just hang, i am using FC18 64 bits. If i turn on the swap, the linux will become very slow, but at least it won’t hang.
So turn on the swap is important when you are playing kvm or openstack.