Gem5v: a modified gem5 for simulating virtualized systems

Abstract

Virtualization is growing in different areas: from powerful servers in data centers to students' laptops and even cell phones. It can provide a more efficient use of hardware resources. Virtualization enables multiple virtual machines to run sideby-side in an isolated environment on a physical hardware. Modern processors are enhanced with technologies like Intel-VT and AMD-V that speed up virtual machines. However, there is still room for improving support of hardware for virtualization workloads. Gem5 is an open-source full system simulator capable of simulating a ChipMultiprocessor with its caches, interconnection network, memory controllers among others. In its current state, gem5 does not support virtualized workloads. In this paper, we present a modified version of gem5, named gem5v, that simulates the behavior of a virtualization layer and can simulate virtual machines. We test this simulator in different scenarios using Parsec, Splash, MapReduce (Phoenix), SPEC and EEMBC benchmarks and compare its measured runtime with real systems. Results show 1-9 % difference between the simulated system and two virtualization softwares on a real hardware, namely KVM and VMware ESX. The comparison of vCPU overhead in VMware ESX and gem5v shows between 0.1 and 9 % difference.