Agenda

• Announcements
  • Lab 5 just about done.
• Last look at SysV Semaphore Example and Implementation
• Monitors, briefly
• Deadlock
  • Idea
  • Necessary conditions: mutex, hold and wait, no preemption, circular wait
  • Resource allocation graphs
  • Prevention
  • Avoidance
  • Banker's Algorithm

Examples

• System V Semaphores:
  • prodcons-sysvsemaphore example
  • implementation: /usr/src/sys/kern/sysv_sem.c
• One-lane tunnel

  

• Banker's Algorithm Examples