A distributed OS uses a distributed control algorithm to implement a control function. The algorithm involves actions in several nodes of the distributed system. This chapter describes the notions of correctness of a distributed control algorithm, and presents algorithms for performing five control functions in a distributed OS - mutual exclusion, deadlock handling, leader election, scheduling, and termination detection. | Chapter 18 Distributed Control Algorithms Copyright © 2008 Operating Systems, by Dhananjay Dhamdhere Introduction Operation of Distributed Control Algorithms Correctness of Distributed Control Algorithms Distributed Mutual Exclusion Distributed Deadlock Handling Distributed Scheduling Algorithms Distributed Termination Detection Election Algorithms Practical Issues in Using Distributed Control Algorithms 18. Operating Systems, by Dhananjay Dhamdhere Copyright © 2008 OS Control Functions in a Distributed Environment Special features of distributed OS control functions Mutual exclusion Involves synchronization of processes in different computers Deadlock handling Deadlocks may involve use of resources in different hosts Scheduling Perform load balancing for comparable loading of computers Termination detection Check whether all processes of a computation, which may operate in different computers, have completed Election Elect coordinator for a privileged function Operating . | Chapter 18 Distributed Control Algorithms Copyright © 2008 Operating Systems, by Dhananjay Dhamdhere Introduction Operation of Distributed Control Algorithms Correctness of Distributed Control Algorithms Distributed Mutual Exclusion Distributed Deadlock Handling Distributed Scheduling Algorithms Distributed Termination Detection Election Algorithms Practical Issues in Using Distributed Control Algorithms 18. Operating Systems, by Dhananjay Dhamdhere Copyright © 2008 OS Control Functions in a Distributed Environment Special features of distributed OS control functions Mutual exclusion Involves synchronization of processes in different computers Deadlock handling Deadlocks may involve use of resources in different hosts Scheduling Perform load balancing for comparable loading of computers Termination detection Check whether all processes of a computation, which may operate in different computers, have completed Election Elect coordinator for a privileged function Operating Systems, by Dhananjay Dhamdhere 18. Operating Systems, by Dhananjay Dhamdhere Copyright © 2008 Operating Systems, by Dhananjay Dhamdhere Operation of Distributed Control Algorithms (continued) A distributed control algorithm operates in parallel with its clients, so that it can respond readily to events related to its service Each process has a control part and a basic part 18. Operating Systems, by Dhananjay Dhamdhere Copyright © 2008 Operating Systems, by Dhananjay Dhamdhere Correctness of Distributed Control Algorithms Algorithm correctness has two facets: Liveness: eventually performs correct actions ., without indefinite delays Safety: does not perform wrong actions Proving correctness of a distributed algorithm is a complex task 18. Operating Systems, by Dhananjay Dhamdhere Copyright © 2008 Operating Systems, by Dhananjay Dhamdhere Correctness of Distributed Control Algorithms (continued) 18. Operating Systems, by Dhananjay Dhamdhere Copyright © .
