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Andrew S. Tanenbaum (OS) Edition 4 Exercise 2 Question 61 (Page No. 179)
Rewrite the program of Fig. $2-23$ to handle more than two processes.
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Andrew S. Tanenbaum (OS) Edition 4 Exercise 2 Question 60 (Page No. 179)
Suppose that a university wants to show off how politically correct it is by applying the U.S. Supreme Court's Separate but equal is ... woman_leaves, man_leaves. You may use whatever counters and synchronization techniques you like.
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Andrew S. Tanenbaum (OS) Edition 4 Exercise 2 Question 59 (Page No. 179)
Solve the dining philosophers problem using monitors instead of semaphores.
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Andrew S. Tanenbaum (OS) Edition 4 Exercise 2 Question 58 (Page No. 179)
Assume that you have an operating system that provides semaphores. Implement a message system. Write the procedures for sending and receiving messages.
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Andrew S. Tanenbaum (OS) Edition 4 Exercise 2 Question 57 (Page No. 178 - 179)
Write a shell script that produces a file of sequential numbers by reading the last number in the file, adding $1$ to it, and then appending it to the file. Run ... to prevent the race.(Hint: use ln file file.lock to lock the data file.)
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Andrew S. Tanenbaum (OS) Edition 4 Exercise 2 Question 56 (Page No. 178)
The readers and writers problem can be formulated in several ways with regard to which category of processes can be started when. Carefully describe three different ... to access the database, and what happens when a process is finished.
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Andrew S. Tanenbaum (OS) Edition 4 Exercise 2 Question 55 (Page No. 178)
Consider the procedure put forks in Fig. $2-47$. Suppose that the variable $state[i]$ was set to THINKING after the two calls to test, rather than before. How would this change affect the solution?
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Andrew S. Tanenbaum (OS) Edition 4 Exercise 2 Question 54 (Page No. 178)
In the solution to the dining philosophers problem (Fig. $2-47$), why is the state variable set to HUNGRY in the procedure take_forks?
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Andrew S. Tanenbaum (OS) Edition 4 Exercise 2 Question 53 (Page No. 178)
Consider a system in which it is desired to separate policy and mechanism for the scheduling of kernel threads. Propose a means of achieving this goal.
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Andrew S. Tanenbaum (OS) Edition 4 Exercise 2 Question 52 (Page No. 178)
A real-time system needs to handle two voice calls that each run every $6$ msec and consume $1$ msec of CPU time per burst, plus one video at $25$ frames/sec, with each frame requiring $20$ msec of CPU time. Is this system schedulable?
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Andrew S. Tanenbaum (OS) Edition 4 Exercise 2 Question 51 (Page No. 178)
In the dining philosophers problem, let the following protocol be used: An even-numbered philosopher always picks up his left fork before picking up his ... picking up his left fork. Will this protocol guarantee deadlock-free operation?
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Andrew S. Tanenbaum (OS) Edition 4 Exercise 2 Question 50 (Page No. 178)
A soft real-time system has four periodic events with periods of $50, 100, 200,$ and $250$ ... , respectively. What is the largest value of $x$ for which the system is schedulable?
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Andrew S. Tanenbaum (OS) Edition 4 Exercise 2 Question 49 (Page No. 178)
The aging algorithm with $a = 1/2$ is being used to predict run times. The previous four runs, from oldest to most recent, are $40, 20, 40,$ and $15$ msec. What is the prediction of the next time?
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Andrew S. Tanenbaum (OS) Edition 4 Exercise 2 Question 48 (Page No. 178)
For the above problem, can another video stream be added and have the system still be schedulable?
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Andrew S. Tanenbaum (OS) Edition 4 Exercise 2 Question 47 (Page No. 178)
Consider a real-time system with two voice calls of periodicity $5$ msec each with CPU time per call of $1$ msec, and one video stream of periodicity $33$ ms with CPU time per call of $11$ msec. Is this system schedulable?
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Andrew S. Tanenbaum (OS) Edition 4 Exercise 2 Question 46 (Page No. 178)
A process running on $CTSS$ needs $30$ quanta to complete. How many times must it be swapped in, including the very first time (before it has run at all)?
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Andrew S. Tanenbaum (OS) Edition 4 Exercise 2 Question 45 (Page No. 177 - 178)
Five batch jobs. $A$ through $E$, arrive at a computer center at almost the same time. They have estimated running times of $10, 6, 2, 4,$ and $8$ ... that only one job at a time runs, until it finishes. All jobs are completely CPU bound.
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Andrew S. Tanenbaum (OS) Edition 4 Exercise 2 Question 44 (Page No. 177)
Five jobs are waiting to be run. Their expected run times are $9, 6, 3, 5,$ and $X$. In what order should they be run to minimize average response time? $($Your answer will depend on $X.)$
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Andrew S. Tanenbaum (OS) Edition 4 Exercise 2 Question 43 (Page No. 177)
Measurements of a certain system have shown that the average process runs for a time $T$ before blocking on $I/O$. A process switch requires a time $S$, which is effectively wasted (overhead ... Q > T$S < Q < T $Q = S$Q\: \text{nearly}\: 0$
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Andrew S. Tanenbaum (OS) Edition 4 Exercise 2 Question 42 (Page No. 177)
Explain how time quantum value and context switching time affect each other, in a round-robin scheduling algorithm.
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Andrew S. Tanenbaum (OS) Edition 4 Exercise 2 Question 41 (Page No. 177)
Can a measure of whether a process is likely to be CPU bound or I/O bound be determined by analyzing source code? How can this be determined at run time?
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Andrew S. Tanenbaum (OS) Edition 4 Exercise 2 Question 40 (Page No. 177)
Round-robin schedulers normally maintain a list of all runnable processes, with each process occurring exactly once in the list. What would happen if a process occurred twice in the list? Can you think of any reason for allowing this?
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Andrew S. Tanenbaum (OS) Edition 4 Exercise 2 Question 39 (Page No. 177)
Consider the following piece of C code: void main( ) { fork( ); fork( ); exit( ); }How many child processes are created upon execution of this program?
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Andrew S. Tanenbaum (OS) Edition 4 Exercise 2 Question 38 (Page No. 177)
The $CDC\: 6600$ computers could handle up to $10\: I/O$ processes simultaneously using an interesting form of round-robin scheduling called processor sharing. ... how much time would it need if processor sharing was used with n processes?
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Andrew S. Tanenbaum (OS) Edition 4 Exercise 2 Question 37 (Page No. 177)
Suppose that we have a message-passing system using mailboxes. When sending to a full mailbox or trying to receive from an empty one, a process does not block ... , over and over, until it succeeds. Does this scheme lead to race conditions?
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Andrew S. Tanenbaum (OS) Edition 4 Exercise 2 Question 36 (Page No. 176)
A fast-food restaurant has four kinds of employees: $(1)$ order takers, who take customers' orders; $(2)$ cooks, who prepare the food; $(3)$ ... What form of interprocess communication do they use? Relate this model to processes in UNIX.
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Andrew S. Tanenbaum (OS) Edition 4 Exercise 2 Question 35 (Page No. 176)
Synchronization within monitors uses condition variables and two special operations, wait and signal. A more general form of synchronization would be to have a single ... is not used. Why not? (Hint: Think about the implementation.)
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Andrew S. Tanenbaum (OS) Edition 4 Exercise 2 Question 34 (Page No. 176)
Can two threads in the same process synchronize using a kernel semaphore if the threads are implemented by the kernel? What if they are implemented in ... threads in any other processes have access to the semaphore. Discuss your answers.
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Andrew S. Tanenbaum (OS) Edition 4 Exercise 2 Question 33 (Page No. 176)
If a system has only two processes, does it make sense to use a barrier to synchronize them? Why or why not?
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Andrew S. Tanenbaum (OS) Edition 4 Exercise 2 Question 32 (Page No. 176)
Show how counting semaphores (i.e., semaphores that can hold an arbitrary value) can be implemented using only binary semaphores and ordinary machine instructions.
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