CS550 Homework Assignment 3

CS550 Advanced Operating Systems

Instructor: Xian-He Sun

Department of Computer Science

Homework 3 (Due Date: 3/10/09, Tuesday)

  1. Exercise 3.3 (Text: Tanenbaum and Steen, Prentice Hall v2)
    In the text, we described a multithreaded file server, showing why it is better than a single-threaded server and a finite-state machine server. Are there any circumstances in which a single-threaded server might be better? Give an example.
  2. Exercise 3.11 (Text: Tanenbaum and Steen, Prentice Hall v2)
    Sketch the design of a multithreaded server that supports multiple protocols using sockets as its transport-level interface to the underlying operating system.
  3. Exercise 3.13 (Text: Tanenbaum and Steen, Prentice Hall v2)
    Is sever that maintains a TCP/IP connection to a client stateful or stateless?
  4. Exercise 3.16 (Text: Tanenbaum and Steen, Prentice Hall v1)
    In Fig. 3-18 it is suggested that strong mobility cannot be combined with executing migrated code in a target process. Give a conterexample.
  5. Exercise 3.7 (Text: Coulouris, Dollimore, and Kindberg, Addison Wesley)
    Compare connectionless (UDP) and connection-oriented (TCP) communication for the implementation of each of the following application-level or presentation-level protocols:
      i)   virtual terminal access (for example, Telnet)
      ii)   file transfer (for example, FTP)
      iii)   user location (for example, rwho, finger)
      iv)   information browsing (for example, HTTP)
      v)   remote procedure call
  6. Exercise 3.8 (Text: Coulouris, Dollimore, and Kindberg, Addison Wesley)
    Explain how it is possible for a sequence of packets transmitted through a wide area network to arrive at their destination in an order that differs from that in which they were sent. Why can't this happen in a local network? Can it happen in an ATM network?
  7. System level VMs support multiple instances of guest OS on single hardware platform. One of the main advantages, claimed by VM proponents, is fault isolation. Is this a perfect isolation? Is it possible to obtain a perfect isolation in the case of user level VM? How about system level VM (type I and II)? Please explain your answers.
  8. Explain the claim that VMM is more stable and more secure than the OS. (Hint: Read Chaper 3 and 4 of the text, and J. Smith's An Overview of Virtual Machine Architectures, available at http://www.ece.wisc.edu/~jes/papers/vms.pdf)

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