Paper Info
Title
Singleton: system-wide page deduplication in virtual environments
Abstract
We investigate memory-management in hypervisors and propose Singleton, a KVM-based system-wide page deduplication solution to increase memory usage efficiency. We address the problem of double-caching that occurs in KVM---the same disk blocks are cached at both the host(hypervisor) and the guest(VM) page caches. Singleton's main components are identical-page sharing across guest virtual machines and an implementation of an exclusive-cache for the host and guest page cache hierarchy. We use and improve KSM--Kernel SamePage Merging to identify and share pages across guest virtual machines. We utilize guest memory-snapshots to scrub the host page cache and maintain a single copy of a page across the host and the guests. Singleton operates on a completely black-box assumption---we do not modify the guest or assume anything about its behaviour. We show that conventional operating system cache management techniques are sub-optimal for virtual environments, and how Singleton supplements and improves the existing Linux kernel memory-management mechanisms. Singleton is able to improve the utilization of the host cache by reducing its size(by upto an order of magnitude), and increasing the cache-hit ratio(by factor of 2x). This translates into better VM performance(40% faster I/O). Singleton's unified page deduplication and host cache scrubbing is able to reclaim large amounts of memory and facilitates higher levels of memory overcommitment. The optimizations to page deduplication we have implemented keep the overhead down to less than 20% CPU utilization.
Year
DOI
Venue
2012
10.1145/2287076.2287081
HPDC
Keywords
Field
DocType
page cache,share page,host cache,guest virtual machine,unified page deduplication,guest page cache hierarchy,kvm-based system-wide page deduplication,virtual environment,guest memory-snapshots,host page cache,page deduplication,memory management,virtualization,operating system,virtual machine
Computer science,Cache,Memory overcommitment,Hypervisor,Real-time computing,Page replacement algorithm,Page cache,Cache coloring,Page fault,Page,Operating system,Distributed computing
Conference
Citations 
PageRank 
References 
40
1.38
25
Authors
2
Name
Order
Citations
PageRank
Prateek Sharma120114.12
Purushottam Kulkarni2130667.96