Title: A Type-Theoretic Framework for Efficient and Safe Colocation of Periodic Real-time Systems 

Author: Vatche Ishakian, Azer Bestavros, and Assaf Kfoury

Date: January 24, 2010

Abstract: 

Desirable application performance is typically guaranteed
through the use of Service Level Agreements (SLAs) that specify
fixed fractions of resource capacities that must be allocated
for {\em unencumbered} use by the application. The mapping
between what constitutes desirable performance and SLAs is not
unique: {\em multiple} SLA expressions might be functionally
equivalent. Having the flexibility to transform SLAs from one
form to another in a manner that is provably {\em safe} would
enable hosting solutions to achieve significant
efficiencies. This paper demonstrates the promise of such an
approach by proposing a {\em type-theoretic} framework for the
representation and safe transformation of SLAs. Based on that
framework, the paper describes a methodical approach for the
inference of efficient and safe mappings of periodic, real-time
tasks to the physical and virtual hosts that constitute a
hierarchical scheduler. Extensive experimental results support
the conclusion that the flexibility afforded by safe SLA
transformations has the potential to yield significant savings.