In this paper, we present an empirical study on the power
consumption of typical computer virtualization packages, including KVM, Xen and OpenVZ, while the systems are performing network tasks. We find that both Hardware Virtualization and Paravirtualization systems add a considerable amount
of energy overhead to networking tasks. Both TCP sending
and receiving can be noticeably affected, and a busy virtualized
web-server may consume up to 40% more energy than its nonvirtualized counterparts. We have conducted detailed profiling
to analyze the workflow for packet delivery in virtualized
machines, which reveals that a VM can take nearly 5 times
more cycles to deliver a packet than a bare-metal machine,
and is also much less efficient on the systems hardware
caches. The existence of hypervisors in VMs can dramatically
increase interrupts and memory accesses, which in turn lead to
significantly more power consumption for network transactions
than a bare-metal machine does