PLRU Cache Domino Effects

Abstract

Domino effects have been shown to hinder a tight prediction of worst case execution times (WCET) on real-time hardware. First investigated by Lundqvist and Stenström, domino effects caused by pipeline stalls were shows to exist in the PowerPC by Schneider. This paper extends the list of causes of domino effects by showing that the pseudo LRU (PLRU) cache replacement policy can cause unbounded effects on the WCET. PLRU is used in the PowerPC PPC755, which is widely used in embedded systems, and some x86 models.