Computer Science MCQS

To recover from failures in network operations, state information is crucial. This information includes details about the current status of connections, data transfers, and other relevant parameters. By maintaining state information, network protocols and applications can restore communication and resend lost data in case of failures.

For example, TCP (Transmission Control Protocol) uses sequence numbers and acknowledgments to keep track of data packets and retransmit lost ones. This state information is essential for reliable data transfer.

The operating system ignores the links when traversing directory trees. This is because links are essentially shortcuts or pointers to existing files or directories, and they don't affect the underlying directory structure. The operating system follows the actual directory paths to navigate the file system.

The operating system maintains an open-file table to keep track of information about all open files. This table contains details such as:

File pointer (current position within the file)

Access permissions

File attributes

Buffer addresses

This information is crucial for efficient file management and access.

The information about all files is kept in a separate directory structure. This structure organizes files and directories hierarchically, making it easy to locate and manage files.

This is correct.

Working set is the set of memory pages actively used by a process. If the total size of all active processes' working sets exceeds the available physical memory, the operating system faces a memory shortage.

To prevent system slowdown or crashes due to excessive page swapping (thrashing), the operating system typically suspends one or more processes. This frees up their memory frames, reducing the overall memory demand and allowing the remaining processes to continue operating efficiently.

If a scheduler assigns a static priority to a process, it means that the priority of that process will not change throughout its lifetime. It remains fixed and is not affected by any other factors like CPU usage, I/O wait time, or other process-related metrics.

This is in contrast to dynamic priority scheduling, where a process's priority can change based on various criteria.

All of the options listed - Windows CE, RTLinux, and VxWorks - are considered real-time operating systems (RTOS). Each is designed to handle time-critical tasks with strict deadlines, making them suitable for applications like industrial control, robotics, and aerospace.

Windows CE: A versatile RTOS developed by Microsoft for embedded systems.

RTLinux: A real-time extension for the Linux kernel.

VxWorks: A widely used commercial RTOS known for its reliability and performance.

Interrupt latency is the time elapsed between an interrupt occurring and the start of its service routine. In real-time systems, where timely responses are critical, minimizing interrupt latency is crucial to ensure that events are handled promptly. A long interrupt latency can lead to missed deadlines and system failures.

Therefore, real-time operating systems employ techniques like priority-based interrupt handling and efficient interrupt service routines to reduce interrupt latency as much as possible.

A hard real-time operating system (RTOS) has less jitter than a soft real-time operating system.

Jitter refers to the variation in response time from one instance to another.

A hard RTOS is designed for systems where missing deadlines can have catastrophic consequences, such as in medical equipment or flight control systems. To ensure this, they have strict timing requirements and minimal jitter.

In contrast, soft RTOS can tolerate some variation in response time without severe consequences.

Therefore, hard RTOS have a much lower tolerance for jitter compared to soft RTOS.

In a real-time operating system (RTOS), the critical characteristic is that tasks have strict deadlines that must be met. If a task is not completed within its specified deadline, it is considered a failure. This is unlike general-purpose operating systems where meeting deadlines is not a strict requirement.