in English Toisella puolella suomeksi

Operating Systems II                                  
Final examination 26.9.2006

Write in each answer sheet your name, signature, id-number, course name, and page nr/total nr of pages
  1. [15 p] Prosesses and threads. Observe Solaris processes and threads (see Fig. 4.15 below). Consider two applications: M and K. They all have 8 threads. Application M is of type 3 (with 3 L threads), and application K of type 4 (with 8 L-threads). Assume that the system has 4 processors. Assume that only one of those applications (M or K) is executed in the system at any given time.
    1. How many threads be executing concurrently in machine language level? Explain why. If needed, you can give a separate answer for applications M and K.
    2. If an executing thread will block because of I/O, will the application block or not? Explain why. If needed, you can give a separate answer for applications M and K.
    3. If an executing thread will block because it waits for another thread in the same application, will the application block or not? Explain why. If needed, you can give a separate answer for applications M and K.
    4. Let us observe one specific thread (Sj) out of 8 threads in the application. When will thread Sj start to execute in some processor? Who makes this decision and when? If needed, you can give a separate answer for applications M and K.
    5. Let us observe one specific processor (Pi). Who makes the decision which process and thread will execute on processr Pi next? How and when is this decision made?

  2. [15 p] Real time scheduling (max 2 pages).
    1. Goals, methods, differences to ordinary scheduling
    2. Example: RMS (Rate Monotonic Scheduling)

  3. [15 p] Virtual memory page replacement algorithms (max 2 pages).
    1. Basic problem, goals, solution methods with their advantages/disadvantages
    2. How does one know how good the solution is?
    3. Practical example and an environment suitable for it

  4. [15 p] RAID (max 2 pages).
      1. Basic problem, goals, solution methods with their advantages/disadvantages
      2. Which RAID would be most suitable for home computer? Why?