Adapting Working-set Theory for Optimal Cache Eviction Florin Coras (Technical University of Catalonia), Damien Saucez (INRIA Sophia Antipolis, France)

1. Using the Working-­‐Set Theory to Model CCN Cache Performance
Florin Coras 1, Damien Saucez2
1Universitat Politècnica de Catalunya, Barcelona, Spain
2Inria, Sophia Antipolis, France
Research challenge Objective
Evaluate cache performance for CCN traffic Evaluate cache performance
Determine best eviction policy
Evaluate link between the demand generating
process and cache performance
Working-­‐Set Theory [DS72]
The Working-‐Set (WS) is typically used to model
OS page caching performance Early Results
Model primitives: programs and pages
100k unique content items
A program can be seen as a reference string: r1, r2
.., where ri is a page out of a set of pages New content inter-‐arrivals ~ EXP(WEB and )
Applicability is conditioned by the reference Inter-‐arrivals of new demands are biased to
increase with time
In order to apply WS theory to CCN type of traffic
we consider the following equivalences:
program demand trace
page demand
If t measures time in content demands then the
WS may be defined as:
W(t,T) is the set of distinct content items that
have been observed among the T most recent
demands
demands tradeoff
t-­‐T+1 t t+1
W(t,T) time
W(t+1,T+1)
Cache size and miss rate tradeoff is possible
Intuitively the WS may be seen as modeling a
cache of size |W(t,T)| Future Work
If s(T) is the average WS size and m(T) is the miss
Stationary locality of reference observed for IP
rate:
packets [FCD12]. Is it for content demands?
Validate with real content demand trace
unique s(T)
demands
Further Reading
m(T)
working-‐
F. Coras, A. Cabellos
T T+1 demands