Runtime monitoring of timing constraints in distributed real-time systems

Embedded real-time systems often operate under strict timing and dependability constraints. To ensure responsiveness, these systems must be able to provide the expected services in a timely manner even in the presence of faults. In this paper, we describe a run-time environment for monitoring of timing constraints in distributed real-time systems. In particular, we focus on the problem of detecting violations of timing assertions in an environment in which the real-time tasks run on multiple processors, and timing constraints can be either inter-processor or intra-processor constraints. Constraint violations are detected at the earliest possible time by deriving and checking intermediate constraints from the user-specified constraints. If the violations must be detected as early as possible, then the problem of minimizing the number of messages to be exchanged between the processors becomes intractable. We characterize a sub-class of timing constraints that occur commonly in distributed real-time systems and whose message requirements can be minimized. We also take into account the drift among the various processor clocks when detecting a violation of a timing assertion. Finally, we describe a prototype implementation of a distributed run-time monitor.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/48087/1/11241_2005_Article_BF01088521.pd

An Automatic Verification Technique for Communicating Real-Time State Machines

We describe an automatic verification technique for distributed real-time systems that are specified as Communicating Real-Time State Machines (CRSMs). CRSMs are timed state machines that communicate synchronously over uni-directional channels. The proposed approach is to model the behavior of the system of (an expressive subclass of) CRSMs by a timed reachability graph. The system behavior of CRSMs is characterized by a time-stamped trace of communication events. We provide a decision procedure for verifying timing and safety properties (specified in a notation based on Real-Time Logic) of the reachability graph, and hence of the corresponding system of CRSMs. We also present a condition for the existence of deadlock in a system of CRSMs. Finally, we briefly describe an implementation of a verifier program based on the above algorithms. Keywords --- automatic verification, deadlock, model checking, reachability, real-time, requirements specification. 1 Introduction The distinguishin..

Monitoring Timing Constraints in Distributed Real-time Systems

In this paper, we describe a run-time environment for monitoring distributed real-time systems. In particular, we focus on the problem of detecting violations of timing assertions in an environment in which the real-time tasks run on multiple processors, and timing constraints can be either inter-processor or intra-processor constraints. Constraint violations are detected at the earliest possible time by deriving and checking intermediate constraints from the userspecified constraints. If the violations must be detected as early as possible, then the problem of minimizing the number of messages to be exchanged between the processors becomes intractable. We characterize a subclass of timing constraints that occur commonly in distributed real-time systems and whose message requirements can be minimized. We also take into account the drift among the various processor clocks when detecting a violation of a timing assertion. Finally, we describe an implementation of a distributed run-time m..