If you can’t verify what you get, …. Reinhard Wilhelm Informatik Saarland University and AbsInt. Messages. An old song: “If you can’t be with the one you love, love the one you’re with!”
Saarland University and AbsInt
The Timing-Analysis Problem
Derive: a guaranteefortimeliness.
Caused by caches, pipelines, speculation etc.
Explosion of state space
“external” interference as seen from analyzed task,
see Jan’s lecture
Hard or impossible to determine
Determine upper bounds instead
Breakthrough in 2001.
C. Ferdinand, R. Heckmann, M. Langenbach, F. Martin, M. Schmidt, H. Theiling, S. Thesing, R. Wilhelm: ReliableandPrecise WCET Determination for a Real-Life Processor. EMSOFT 2001: 469-485
Components with domains of states C1, C2, … , Ck
Analysis has to track domain C1 C2… Ck
Start with the powerset domain 2 C1 C2… Ck
Find an abstractdomain C1#
transforminto C1# 2 C2… Ck
Find abstractions C11# and C12#
factor out C11# andtransform
rest into 2 C12# … Ck
This has worked for caches and
This has worked for the arithmetic
of the pipeline.
2 C12# … Ck
Two different problems - two different originators
Reconcile performance with predictability in architectural design
Current architectures are optimized for average-case performance
Question: How can one design an architecture with efficiently determinable good worst-case performance?
Strong results on caches, PhD dissertation of Jan Reineke
PPES Workshop at DATE 2011 in Grenoble
Paper by AbsInt on Dos and DON’Ts