Operating Systems Question Bank with Answers 20

Describe the differences among short-term, medium-term, and long-term scheduling.

Question:

Describe the differences among short-term, medium-term, and long-term scheduling.

Answer:

Short-term (CPU scheduler): selects a process from those that are in memory and ready to execute, and allocates the CPU to it.

Medium-term (memory manager): selects processes from the ready or blocked queue and removes them from memory, then reinstates them later to continue running. It is used especially with time-sharing systems as an intermediate scheduling level.

Long-term (job scheduler): determines which jobs are brought into the system for processing. It is responsible for controlling the degree of multi-processing.

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• What is busy waiting with respect to a critical section problem? Can busy waiting be avoided?

• List the different inter process communication (IPC) mechanisms with examples.

• Describe the differences between symmetric and asymmetric multiprocessing. What are advantages and disadvantage of multiprocessor systems?

• What is a file descriptor? What are the file descriptors in Unix OS for stdin, stdout, and stderr respectively?

• What is a special file? Define block special file and character special file with examples. What is the essential difference between a block special file and a character file?

• List three main advantages of Virtual Memory.

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• What are the major activities of an operating system in regard to process management?

Operating Systems Question Bank with Answers 21

What are the major activities of an operating system in regard to process management?

Question:

What are the major activities of an operating system in regard to process management?

Answer:

• The creation and deletion of both user and system processes.

• The suspension and resumption of processes

• The provision of mechanisms for process synchronization

• The provision of mechanisms for process communication

• The provision of mechanisms for deadlock handling

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• Distinguish between traditional interrupt-based I/O and DMA-based I/O.

• What is busy waiting with respect to a critical section problem? Can busy waiting be avoided?

• List the different inter process communication (IPC) mechanisms with examples.

• Describe the differences between symmetric and asymmetric multiprocessing. What are advantages and disadvantage of multiprocessor systems?

• What is a file descriptor? What are the file descriptors in Unix OS for stdin, stdout, and stderr respectively?

• What is a special file? Define block special file and character special file with examples. What is the essential difference between a block special file and a character file?

• List three main advantages of Virtual Memory.

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• Describe the differences among short-term, medium-term, and long-term scheduling.

• What are the major activities of an operating system in regard to process management?

Operating Systems Question Bank with Answers 12

Distinguish between traditional interrupt-based I/O and DMA-based I/O.

Question:

Distinguish between traditional interrupt-based I/O and DMA-based I/O.

Answer:

Traditional Interrupt-based I/O:

• Device interrupts the CPU when it needs attention

• CPU is required to perform the I/O operation

• CPU stops processing other jobs while servicing the interrupt

DMA-based I/O:

• CPU is required to initialize memory, registers, counters

• DMA controller (not CPU) handles I/O operations

• Interrupt generated each time an entire block is transferred

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Related Questions:

• Distinguish between traditional interrupt-based I/O and DMA-based I/O.

• What is busy waiting with respect to a critical section problem? Can busy waiting be avoided?

• List the different inter process communication (IPC) mechanisms with examples.

• Describe the differences between symmetric and asymmetric multiprocessing. What are advantages and disadvantage of multiprocessor systems?

• What is a file descriptor? What are the file descriptors in Unix OS for stdin, stdout, and stderr respectively?

• What is a special file? Define block special file and character special file with examples. What is the essential difference between a block special file and a character file?

• List three main advantages of Virtual Memory.

• What are the differences between a trap and an interrupt? What is the use of each function?

• Describe the differences among short-term, medium-term, and long-term scheduling.

• What are the major activities of an operating system in regard to process management?