Operating Systems Quiz

A computer has 256 MB of RAM of which the operating system occupies 64 MB. The processes are all 64 MB (for simplicity) and have the same characteristics. If the goal is 48.8% CPU utilization, what is the maximum I/O wait percentage that can be tolerated?

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Consider a swapping system in which memory consists of the following hole sizes in memory order: 13 MB, 1 MB, 8 MB, 5 MB, 6 MB, 4 MB, 21 MB, and 1 MB. Which holes are taken for successive segment requests of 3 MB, 6 MB, 2 MB for next fit algorithm?

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Which of the following are ways to avoid or resolve race condition? Select all that apply.

• Using locks or other synchronization primitives

• Restricting access to shared resources

• Using atomic operations or transactions

• Using multithreading instead of multiprocessing

Which UNIX system call is used to change the working directory?

• chdir

• umount

• chmod

Virtual address space allows a process to access physical memory directly without the need for translation.

• True

• False

Which does not happen during context switch?

• Saving and loading registers and memory maps

• Restore the contents of the files opened by the process

• Updating various tables and lists

• Flushing and reloading the memory cache

Which of the following is NOT a state that a process can be in?

• Running

• Blocked

• Ready

• Stopped

Which are true? Select all that apply.

• In a timesharing system, multiple users can access and perform computations on a computing system simultaneously using their own terminals

• All multiprogramming systems are timesharing systems.

• Multiprogramming systems allow a user to run multiple programs simultaneously

• Not all timesharing systems are multiprogramming systems

Consider five jobs, A through E with run times of 12, 9, 7, 3 and 25, respectively. Their arrival times are 0, 0, 2, 4, and 39. What is the average wait time if they are run using the shortest job first algorithm?

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The aging algorithm with the smoothing value of 3/4 is being used to predict run times. The previous three runs, from the most recent to the oldest, are 20, 24, and 16 seconds. What is the prediction of the next time in seconds.

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