Overcommitting Memory by Initiative Share from KVM Guests

Abstract

In virtualized environments, physical resources are abstracted as resource pool for provisioning, services consolidation, and service on demand. Traditional virtual machines are often over-provisioned to provide peak performance guarantees and thus waste a lot of memory resources. In this paper we propose a novel Initiatively Share Based Memory Overcommitting scheme, namely, IMR, to improve the memory utilization further. In IMR, guest virtual machine kernels are hacked with initiatively share functionality such that the guests can cooperatively share unused memory with the hypervisor, and consequently some of the possible page swapping and merging in such virtual machines are eliminated. The experimental results in shadow page tables and extended page tables scenarios show that our IMR approach not only improves the memory utilization but also has microsecond-level time overheads for shared memory reclaim, which outperforms the memory optimization schemes such as millisecond-level KSM (Kernel Same-page Merging) in best cases and millisecond-level page swapping at average.