Three general approaches for dealing with deadlock.

1. Deadlock Detection and Recovery

Detect deadlock and, when it occurs, take steps to recover.

2. Deadlock Avoidance

Avoid deadlock by careful resource scheduling.

3. Deadlock Prevention

Prevent deadlock by resource scheduling so as to negate at least one of the four conditions.

18. Which of the replacement algorithms selects for replacement that page for which the time to the next reference is the longest? optimal

19. What does process page table entry contain? A page table is the data structure used by a virtual memory system in a computer operating system to store the mapping between virtual addresses and physical addresses.

20. Suppose, the page table of process contains 3 pages. Given the such order of page references\: 4, 0, 0, 0, 2, 4, 2, 1, 0, 3, 2. Calculate number of page faults using LRU(least resent used)\:

21. Suppose, the page table of process contains 3 pages. Given the such order of page references\: 4, 0, 0, 0, 2, 4, 2, 1, 0, 3, 2. Calculate number of page faults using Optimal algorithm of replacement\:

22. Which of the replacement algorithms treats the page frames allocated to a process as a circular buffer? clock

23. What is the real address? The address of a storage location in main memory.

24. What is virtual address? The address assigned to a location in virtual memory to allow that location to be accessed as though it were part of main memory.

25. The size of virtual storage is limited by... The size of virtual storage is limited by the addressing scheme of the computer system and by the amount of secondary memory available and not by the actual number of main storage locations.

26. What is the resident set of the process?

The portion of process that is actually in main memory at any time

27. When does processor generate an interrupt indicating a memory access fault?

If processor encounters a logical address that is not in main memory(page fault)

What is trashing?Thrashing occurs when a system spends more time processing page faults than executing transactions.

28. What are three versions of load sharing approach in multiprocessor thread scheduling and processor assignment?

- First come first served (FCFS):

- Smallest number of threads first:

- Preemptive smallest number of threads first:

29. Fill in the gaps in description. 1 .Determinism __ is concerned with how long an operating system delays before acknowledging an interrupt. 2._ Responsiveness ___ is concerned with how long, after acknowledgment, it takes an operating system to service the interrupt.

30. What is NOT the feature of real-time operating systems?

is

• Fast process or thread switch

• Small size (with its associated minimal functionality)

• Ability to respond to external interrupts quickly

• M10_STAL6329_06_SE_C10.QXD 2/21/08 9:33 PM Page 468

• Multitasking with interprocess communication tools such as semaphores, signals,

• and events

• Use of special sequential files that can accumulate data at a fast rate

• Preemptive scheduling based on priority

• Minimization of intervals during which interrupts are disabled

• Primitives to delay tasks for a fixed amount of time and to pause/resume tasks

• Special alarms and timeouts

31. Which of the following is not a class of real-time scheduling algorithms?

32. Define synchronization granularity by description\: multiprocessing of concurrent processes in a multiprogramming environment

33. Define synchronization granularity by description\: distributed processing across network nodes to form a single computing environment.

34. Define synchronization granularity by description\: multiple unrelated processes.

33-34-35

35. What are the advantages of load sharing approach in multiprocessor thread scheduling and processor assignment?

• The load is distributed evenly across the processors, assuring that no processor is idle while work is available to do.

• No centralized scheduler is required; when a processor is available, the scheduling

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