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Homework                                           [suomeksi Sivu suomen kielellä]

Operating Systems II,  Spring 2005, HW 3

This will be covered in practise session during the week 15 (12-14.4.2005)

  1. Replacement algorithm
    1. Problem 8.5 from text book [Stal05, s. 384] (Probl. 8.3 [Stal01])
    2. What is special with this situation? What can you deduce from it?

  2. VSWS
    1. Problem 8.16 from text book [Stal05] (Probl. 8.13 [Stal01])
    2. What if Q was global, but dynamic. Give a similar mechanism for this case. Compare it to the mechanism given in (a). When would it be better? When worse?
       
  3. Clock-algorithm
    1. Which page would be replaced in situation in Fig. 8.16 (b) [Stal05] (Fig. 8.16 [Stal01])?
    2. When exactly is use-bit set and reset? (Fig 8.16)
    3. If modified bit is also use, when is that exactly set and reset?
      (Fig 8.18 [Stal05] tai kuva 8.18 [Stal01])
    4. How much variance is there in the gap between the hands in Fig. 8.23 [Stal05] ( kuva 8.23 [Stal01])?
      Who varies it and how much? What does the gap value mean?
    5. How is the moving hand speed varied in Fig 8.23 or is it a constant?
      What does moving hand speed mean?

     
  4. Cleaning policy
    1. What does Cleaning Policy really mean?
    2. Why is it not integrated with Replacement Policy? Advantages? Problems?
    3. Give an example on a situation where replacement is needed, but cleaning is not.
    4. What happens, if a reference occurs to a page while it is been cleaned?
    5. What happens, if a reference occurs to a page right after it has been cleaned?

     
  5. Linux. Linux memory management maps a conquous virtual memory area into a contiquous block of physical frames.
    1. What is the gain with this approach?
    2. What problems does it cause?
    Consider both general memory management policies as well as physical device usage.

     
  6. What are the biggest differences in
    1. W2K
    2. Linux
    memory management as compared basic methods described in Ch 8.2 [Stal05]?
    Fetch policy? Placement policy? Replacement policy? Cleaning policy? Load control? Resident set?

    (If you were not at the lecture, check (e.g.) Ch. 10.4 and 11.5 [Tane01] for a little bit  more thorough W2K and Linux VM presentation than that given in Ch 8 [Stal05])
Teemu Kerola 30.03.2005 13:49