Wait-Free Snapshots in Real-Time Systems: Algorithms and Performance

Snap-shot mechanisms are used to read a globally consistent set of variable values. Such a mechanism can be used to solve a variety of communication and synchronization problems, including system monitoring and control of real-time applications. Methods based on locking (e.g. using semaphores) are penalized by blocking, which typically leads to difficulties in guaranteeing deadlines of high priority tasks. Lock-free methods, which take a snap-shot and then check if it corresponds to a consistent system state, have unpredictable timing-behavior, since they may have to retry an unpredictable number of times. Clearly, a method which combines the predictability of locking-based methods with the low interference (no blocking) of lock-free methods is desirable. In this paper we present one such method, based and the concept of wait-freeness. A wait-free method is a lockfree method which is guaranteed to correctly complete in a bounded number of steps. The price to pay for this predictabilit...

• Type: Conference
• Year: 1998
• Where: RTCSA
• Authors: Andreas Ermedahl, Hans Hansson, Marina Papatriantafilou, Philippas Tsigas
• Keywords: Embedded Systems, Lock-free Methods, RTCSA 1998, Snap-shot Mechanisms, Wait-free Method