1. IMPLEMENTATION OF LAMPORT’S SCALAR CLOCKS Surekha Busa

2. Contents  Introduction  Implementation Rule  Experimental Setup  Result Analysis  Observation  Future Work

3. INTRODUCTION  To show casualty in distributed system  Each process P i has a logical clock C i assigned with an integer  the assigned value is the timestamp of this event, denoted C(a)  The timestamps are monotonically increasing  consistency condition  consistency: if a  b, then C(a)  C(b) if event a happens before event b, then the clock value (timestamp) of a should be less than the clock value of b  strong consistency: if C(a)  C(b) then a  b  scalar clocks are not strongly consistent

4. IMPLEMENTATION RULE  Outgoing messages tagged with Sender’s clock value  Upon receive of message: myclock = MAX(message, myclock)

5. EXPERIMENTAL SETUP  Base Algorithm : Random Flood.  Whenever the clock of the receiver take the value of the clock of the message we say the clock is updated.  Total No. of updates per process(number of updates/no of processes) is calculated by increasing the number of processes from 10-100. P1P1 e11 (1) e12 (2) e13e14 (4) e15 (5) P2P2 e21 (1) e22 (2) e23 (4) (3) Clock is Updated Clock is not Updated

6. RESULT ANALYSIS: No. Of Updates and Messages Varying No. Of Processes

7. RESULT ANALYSIS: No. Of Updates and Messages Per Process Varying No. Of Processes

8. RESULT ANALYSIS: No. Of Messages Versus No. Of Clock Updates

9. No. Of Processes No. Of UpdatesNo. Of Messages Updates Per Process Messages Per Process 1013461.34 20411972.059 30654422.1714 40958292.3720 5013112302.6224 6016917242.8128 7020625092.9435 802403238340 9027840813.0845 10031949383.1949

10. OBSERVATION  No. Updates and messages per process increases with increase in No. of Processes.  No. of clock updates increase with increase in No. of Messages.

11. FUTURE WORK  To observe its performance over various topologies.  To test my program with much larger no. of processes.  Test my program on a real distributed network.

12. REFERENCE [1] Leslie Lamport (1978). ”Time, clocks, and the ordering of events in a distributed system”. Communications of the ACM 2 (7): 558-565. [2] Mukesh Singhal,Niranjan G. Shivaratri.“Advanced Topics in Operating Systems”. McGRAW-Hill international edition:Chapter 5. Code Defence

13. THANK YOU..!!