The Nevercrash Operating System Company has been receiving complaints from some of its customers about its latest release, which includes semaphore operations. They feel it is immoral for processes to block (they call it "sleeping on the job"). Since it is company policy to give the customers what they want, it has been proposed to add a third operation, peek, to supplement up and down. peek simply examines the semaphore without changing it or blocking the process. In this way, programs that feel it is immoral to block can first inspect the semaphore to see if it is safe to do a down. Will this idea work if three or more processes use the semaphore? If two processes use the semaphore?

The Nevercrash Operating System Company has been receiving complaints from some of its customers about its latest release, which includes semaphore operations. They feel it is immoral for processes to block (they call it "sleeping on the job"). Since it is company policy to give the customers what they want, it has been proposed to add a third operation, peek, to supplement up and down. peek simply examines the semaphore without changing it or blocking the process. In this way, programs that feel it is immoral to block can first inspect the semaphore to see if it is safe to do a down. Will this idea work if three or more processes use the semaphore? If two processes use the semaphore?

Database System Concepts

7th Edition

ISBN:9780078022159

Author:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan

Publisher:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan

Chapter1: Introduction

Section: Chapter Questions

Problem 1PE

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Computer screens often use the WIMP layout. The Desktop metaphor is widely used in WIMP implementations, and it maps typical operations to their concrete equivalents. To move a file, just click and drag it to its new home (a different folder or the desktop). Give us two procedures and the situations in which they might be used.
The typical computer screen has a WIMP setup (what does WIMP stand for?). Most common WIMP arrangements work on the basis of a desktop metaphor, in which common actions are likened to similar actions in the real world. For example, moving a file is achieved by selecting it and dragging it into a relevant folder or filing cabinet. The advantage of using a metaphor is that the user can identify with the environment presented on the screen. Having a metaphor allows users to predict the outcome of their actions more easily. Note that the metaphor can break down, however. What is the real-world equivalent of formatting a disk? Is there a direct analogy for the concept of ‘undo’?
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Is it possible for a single process to get stuck in the middle of its execution? Please provide justifications for your responses.
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What exactly is meant by the word "Access Point"? What exactly is the process that's going on here?
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This exercise involves printing out the generations of a series of processes created using fork(). You will create a program that accepts a single command line argument indicating the number of generations that should be created. For each generation, your program will fork a child process until you have created a series of children of the right length. Each process should print its own generation, in reverse order. When the generations are printed, each process should print its own process ID, as well as the process ID of its parent process. Example Output Here are some sample runs: No argument If no argument is provided, the program should print a message and exit S . /generations Usage: ./generations num_generations Invalid argument If the argument is less than 0, the program should print a message and exit $ ./generations -1 Error: num generations must be greater than e Correct Argument s ./generations 5 Great Great Great Grandchild. pid: 5732 ppid: 5731 Great Great Grandchild. pid:…
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