Title
Probabilistic WCET estimation in presence of hardware for mitigating the impact of permanent faults.
Abstract
Fine-grained disabling and reconfiguration of hardware elements (functional units, cache blocks) will become economically necessary to recover from permanent failures, whose rate is expected to increase dramatically in the near future. This fine-grained disabling will lead to degraded performance as compared to a fault-free execution. Until recently, all static worst-case execution time (WCET) estimations methods were assuming fault-free processors, resulting in unsafe estimates in the presence of faults. The first static WCET estimation technique dealing with the presence of permanent faults in instruction caches was proposed in [1]. This study probabilistically quantified the impact of permanent faults on WCET estimates. It demonstrated that the probabilistic WCET (pWCET) estimates of tasks increase rapidly with the probability of faults as compared to fault-free WCET estimates. In this paper, we show that very simple reliability mechanisms allow mitigating the impact of faulty cache blocks on pWCETs. Two mechanisms, that make part of the cache resilient to faults are analyzed. Experiments show that the gain in pWCET for these two mechanisms are on average 48% and 40% as compared to an architecture with no reliability mechanism.
Year
Venue
Keywords
2016
DATE
fine-grained disabling,hardware elements reconfiguration,functional units,permanent failures,fault-free execution,static worst-case execution time estimations methods,static WCET estimations methods,fault-free processors,instruction caches,probabilistic WCET estimates,pWCET estimates,faulty cache blocks
Field
DocType
ISSN
Computer science,Cache,Parallel computing,Real-time computing,Probability distribution,Execution time,Probabilistic logic,Computer hardware,Control reconfiguration,Embedded system
Conference
1530-1591
Citations 
PageRank 
References 
4
0.38
12
Authors
3
Name
Order
Citations
PageRank
Damien Hardy116110.07
Isabelle Puaut2170889.84
Yiannakis Sazeides366267.55