Operating systems

Apr 27th, 2014
Price: $10 USD

Question description

  1. Assume a system has P processes and R identical units of a reusable resource. If each process can claim at most N units of the resource, determine whether each of the following is true or false and prove your claim:(a) If the system is deadlock free then R ≥ P(N - 1) + 1. 
    (b) If R ≥ P ( N - 1) + 1 then the system is deadlock free.
  2. ( 10 points ) 
    In this problem you are to compare reading a file using a single-threaded file server and a multithreaded server. It takes 15 msec to get a request for work, dispatch it, and do the rest of the necessary processing, assuming that the data needed are in a cache in main memory. If a disk operation is needed, as is the case one-third of the time, an additional 75 msec is required, during which time the thread sleeps. How many requests/sec can the server handle if it is single threaded? If it is multithreaded? 
  3. ( 10 points ) 
    Suppose we use the following to denote a resource graph:Pi : process i 
    Rj: resource type j; can have 1 or more units 
    Pi → Rj : Pi is making a request for resource Rj 
    Pi ← Rj : one unit of resource Rj has been assigned to PiConsider the following resource graph: R1 has two units, R2 has two units, and R3 has one unit,
    • P
    1 → R1, P2 → R2, P3 → R2, P4 → R2, P5 → R3
    P4 ← R1, P3 ← R2, P5 ← R2, P3 ← R3,

    Draw the graph. Give an example of a knot in the graph and explain why it is a knot. If you find that there's no knot in the graph, express the answer as an empty set. 

  4. ( 10 points ) 
    Consider the state of a system with processes P1, P2, and P3, defined by the following matrices.max-Avail A = ( 5 2 4 )
    Max-Claim B =3matrixleft.gif
    2 2 2
    1 2 2
    3 1 3
    Allocation C =
    1 1 0
    1 0 1
    1 1 1

    a) Find the available matrix D and need matrix E in this state.

    b) Suppose now process P1 makes a request with

    F1 = ( 0 0 1 )
    If the request were granted, what would be  the D, C, and E in the resulted state?

    c) To ensure the system be safe, should the request be granted? Why? Give your reasons in detail. 

  5. ( 20 points ) 
    Make use of condition variables to implement the barrier problem in Java. A barrier is a synchronization construct that set up for a specified number of threads, say n. Thread that have entered the barriercannot exit until all n threads have entered. Once all threads have entered and they being to exit, the barrier resets itself so that another set of n threads enter again, which again cannot exit until all have entered. 

Tutor Answer

(Top Tutor) nava
School: Boston College

Studypool has helped 1,244,100 students

Review from student
" Thanks, good work "
Ask your homework questions. Receive quality answers!

Type your question here (or upload an image)

1830 tutors are online

Brown University

1271 Tutors

California Institute of Technology

2131 Tutors

Carnegie Mellon University

982 Tutors

Columbia University

1256 Tutors

Dartmouth University

2113 Tutors

Emory University

2279 Tutors

Harvard University

599 Tutors

Massachusetts Institute of Technology

2319 Tutors

New York University

1645 Tutors

Notre Dam University

1911 Tutors

Oklahoma University

2122 Tutors

Pennsylvania State University

932 Tutors

Princeton University

1211 Tutors

Stanford University

983 Tutors

University of California

1282 Tutors

Oxford University

123 Tutors

Yale University

2325 Tutors