Advanced Operating Systems- Clock synchronization and mutual exclusive
- 1. Advanced Operating Systems I MCA- II SEMESTER SUBJECT CODE : P22MCACC22 UNIT – II Clock Synchronization & Mutual Exclusion Presented By S.Vijaya Lakshmi B.E(CSE) Assistant Professor, Department of Computer Science, Sri Sarada Niketan College for Women,Karur.
- 2. Clock Synchronization in Distributed System Clock synchronization is the mechanism to synchronize the time of all the computers in the distributed environments or system. Assume that there are three systems present in a distributed environment.
- 3. Properties of Distributed algorithms to maintain Clock synchronization: • Relevant and correct information will be scattered among multiple machines. • The processes make the decision only on local information. • Failure of the single point in the system must be avoided. • No common clock or the other precise global time exists. • In the distributed systems, the time is ambiguous.
- 4. Types of Clock Synchronization Physical clock synchronization Logical clock synchronization Mutual exclusion synchronization
- 5. Mutual exclusion in distributed system Mutual exclusion is a concurrency control property which is introduced to prevent race conditions. It is the requirement that a process can not enter its critical section while another concurrent process is currently present or executing in its critical section i.e, only one process is allowed to execute the critical section at any given instance of time.
- 6. Requirements of Mutual exclusion Algorithm: No Deadlock No Starvation Fairness Fault Tolerance
- 7. Solution to distributed mutual exclusion: Token Based Algorithm Non-token based approach Quorum based approach
- 8. Election algorithm It assumes that every active process in the system has a unique priority number. The process with highest priority will be chosen as a new coordinator. Hence, when a coordinator fails, this algorithm elects that active process which has highest priority number.
- 9. Distributed Deadlock Detection Distributed deadlocks can occur when distributed transactions or concurrency control are utilized in distributed systems. It may be identified via a distributed technique like edge chasing or by creating a global wait-for graph (WFG) from local wait-for graphs at a deadlock detector.
- 10. Types of deadlock detection An operating system (OS) can detect deadlocks by using one of the four common algorithms: Banker's algorithm, Resource Hierarchy algorithm, Deadlock Detection Algorithm or Wait-For-Graphs.
- 11. Process Deadlocks in Operating System Coffman Conditions. A deadlock occurs if the four Coffman conditions hold true. Deadlock Detection. A deadlock can be detected by a resource scheduler as it keeps track of all the resources that are allocated to different processes. Deadlock Prevention. Deadlock Avoidance.
- 12. Thank You