GIT-CERCS-08-06
Balasubramanian Seshasayee, Karsten Schwan,
Creating Efficient Execution Platforms with V(irtualized) Services
Virtualization is creating new opportunities for innovative
uses of middleware technologies. In this paper, we present such opportunities
for mobile or pervasive environments, where virtualization eff orts
face challenges that include the diversity of platforms and devices present
in these domains, dynamic device and resource behaviors, and the efficient use and sharing of such resources. Speci fically, we leverage middleware
to signi ficantly extend virtualization technologies in terms of their
efficient support for resource sharing in the presence of diversity, dynamics,
and mobility. The outcome is what we term the Virtualized Services
(VServices) approach to representing and using devices and resources.
VServices extend the virtual device interfaces used in existing virtualization
infrastructures to go beyond sharing physical devices among multiple
virtual machines, to also sharing logical entities that internally use
middleware to provide new services to end user applications. By using
and sharing the higher level VServices abstractions instead of physical
devices, opportunities are created (i) to optimize the implementations of
certain services without requiring changes to VM implementations, (ii) to
enhance device functionalities by combining software service implementations
with the physical devices being used, again without changing
the basic nature of VM-device interactions, and (iii) to emulate devices
whose physical realizations may be remote or non-existent. Experimental
evaluations conducted on an implementation of these concepts in the Xen
virtualization infrastructure exhibit up to 50% improvements in latency
as well as improved performance scalability, when compared to current
Xen implementations of such devices. This paper also describes practical
realization of device enhancements using VServices.