1. Y.C. Tay National University of Singapore
Dynamic System Optimization through Performance Modeling: Universality and Decomposition
Y.C. Tay
National University of Singapore

2. Dynamic optimization is hard.
Examples:
Prob(miss) = f(cache size)
Given target Prob(miss), how to dynamically adjust cache size?
Universality
(2) Internet traffic equilibrium
How to prevent performance collapse from congestion?
Decomposition

3. (1) Universality reference pattern cache size management policy
issue: Prob(miss) = f(cache size)
reference
pattern
cache
size
management
policy
complex
add:
● system customization
● hw/sw evolution
● autonomic configuration
● dynamic adjustment
hardware
variation
data
layout
application
mix
software
variation
data
instance
intractable!
system
configuration

4. (1) Universality no change
idea: Prob(miss) = f(cache size | parameters)
change values
● system customization
● hw/sw evolution
● autonomic configuration
● dynamic adjustment

5. (1) Universality = (H + √(H 2 – 4))(n*+n0) – n0
idea: Prob(miss) = f(cache size | parameters)
#miss = f (M | M*, M0, n*, n0)
change values
= (H + √(H 2 – 4))(n*+n0) – n0 1 2
where
H =
1 +
M* - M0
M - M0
● system customization
● hw/sw evolution
● autonomic configuration
● dynamic adjustment

6. (1) Universality = (H + √(H 2 – 4))(n*+n0) – n0
#miss = f (M | M*, M0, n*, n0)
= (H + √(H 2 – 4))(n*+n0) – n0 1 2
where
H =
1 +
M* - M0
M - M0
Example: cache=RAM