Department of Computer Science

Department information

 

Operating Systems, Fall 2007, Homework 11

This homework will be covered in practise session on Thursday 29.11.2006 (week 48).

The exercises are based on chapters 14 and 15.

1. Problem 14.3. a) and b) from text book [Stal05, p. 640] (problem 13.3 [Stal01, p. 605])
   

2. Clustering and Grid-computing (as defined at the end of Lecture 12)
   1. What are the main differences between Beowulf Linux Cluster and Windows 2000 Cluster Server. How do they affect the applications?
   2. What kind of application that would be suitable for clusters but not for grids. Why?
   3. Which synchronization primitives are suitable for SMP, but not for clusters? Why?
   4. Which synchronization primitives are suitable for clusters, but not for grids? Why?

3. Ordering of events
   1. Problem 15.2 from text book [Stal05, p. 676] (problem 14.2. [Stal01, p.644 ])
      
   2. The pure Lamport's logical timestamp scheme gives us a happens-before relatioship: If event A happens before event B, then the timestamp of A is less than the timestamp of B. Note, however, that one cannot order two event based only on their timestamps. The fact that an event C has a timestamp that is less than the timestamp of event D does not necessarily mean that event C happened before event D; C and D could be concurrent events in the system. Discuss ways in which the logical clock timestamp scheme could be extended to distinguish concurrent events from event that can be ordered by the happens-before relatioship.

4. Mutual exclusion
   1. Problem 15.3 from text book [Stal05, p. 676] (problem 14.3. [Stal01, p.644 ])
      
   2. Your company is building a computer network, and you are asked to write an algorithm for achieving distributed mutual exclusion. Which scheme will you use? Explain your choise.

---

Tiina.Niklander@cs.helsinki.fi