Computer Science 330
Operating Systems

Spring 2012, Siena College

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Agenda

• Announcements
  • Lab tomorrow: mostly shell-related things, final project discussion, library session at 11:30
  • Scheduling presentations for Monday, April 30 - send your availability
• Midterm exam due
• Deadlock
  • Deadlock prevention
  • Deadlock avoidance
    • augmented resource allocation graphs
    • Banker's Algorithm
  • Detection and recovery
• Memory Management
  • Binding time
    • Programming or compile time
    • Load time
    • Execution time
  • Logical vs. Physical Address Space
  • Memory protection
  • Swapping
  • Contiguous allocation
    • hardware support: limit and base/relocation registers
    • first-fit/best-fit/worst-fit
  • Fragmentation
    • external: waste between allocated chunks
    • internal: waste within allocated chunks
    • reduce external fragmentation with a compaction operation

Lecture Assignment 14

Due at the start of class, Tuesday, March 20.

Please submit answers to these questions either as a hard copy (typeset or handwritten are OK) or by email to jteresco AT siena.edu by the start of class. Please use a clear subject line when submitting by email (e.g., CS 330 Lecture Assignment 14, Joe Student). We will discuss these questions at the start of class, so no late submissions are accepted.

• SG&G Exercise 6.34, p. 265 (6 points)
• SG&G Exercise 6.35, p. 265 (4 points)
• Consider this resource allocation state for four different non-preemptible resource types R0, R1, R2, and R3. Assume maximum claims and current resource assignments for five processes P0, P1, P2, P3, and P4, are given in the following table, along with the total number of each resource available (not including allocated resources).

  	Max Claims					Current Use
  Resource	P0	P1	P2	P3	P4	P0	P1	P2	P3	P4	Avail
  R0	0	1	2	0	0	0	1	1	0	0	1
  R1	0	7	3	6	6	0	0	3	6	0	5
  R2	1	5	5	5	5	1	0	5	3	1	2
  R3	2	0	6	2	6	2	0	4	2	4	0

  Is this state safe? (4 points)

• If a request arrives from process P0 for 4 instances of R1 and 2 instances of R2, can the request be granted immediately? (4 points)

The readings for next class are SG&G Chapter 7.

Examples

• Banker's Algorithm Example