Operating System Concepts

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Questions and Answers

In the context of deadlock prevention, which of the following strategies represents the MOST pragmatic approach to handling the 'circular wait' condition, considering both efficacy and minimal performance overhead?

Dynamically adjusting process priorities based on their resource holding time, favoring processes holding fewer resources to break potential circular dependencies.
Using a preemption strategy where resources are forcibly taken away from processes suspected of involvement in a circular wait condition.
Implementing a timeout mechanism that automatically releases all resources held by a process if it waits longer than a predefined interval for an additional resource.
Employing a global numbering scheme for all resource types and mandating that processes request resources in strictly ascending order. (correct)

How does the implementation of a real-time operating system (RTOS) kernel's scheduler typically differ from that of a general-purpose OS scheduler in handling process context switches?

RTOS schedulers minimize context switch latency through techniques like shadow registers and optimized interrupt handling, while general-purpose OS schedulers prioritize overall throughput. (correct)
RTOS schedulers use a fixed time quantum for all processes, ensuring fairness, while general-purpose OS schedulers employ variable quanta based on process priority.
RTOS schedulers rely on hardware-based context switching mechanisms, whereas general-purpose OS schedulers implement context switching in software.
RTOS schedulers perform context switches only at predefined synchronization points, while general-purpose OS schedulers can perform context switches at any point.

Consider a system employing a multi-level feedback queue scheduling algorithm. What adjustments to the algorithm's parameters would MOST effectively reduce the likelihood of starvation for I/O-bound processes?

Decreasing the number of queues in the scheduler, consolidating the priority levels and reducing the disparity in execution opportunities.
Implementing a dynamic priority adjustment mechanism that increases the priority of processes based on their waiting time in the ready queue. (correct)
Increasing the time quantum for queues with higher priorities, allowing I/O-bound processes to complete their tasks more quickly.
Periodically boosting the priority of all processes, ensuring that even those in lower-priority queues eventually get a chance to run.

In the context of memory management, which strategy offers the MOST effective mitigation against external fragmentation while simultaneously accommodating variable-sized memory allocations?

Adopting a slab allocation technique optimized to allocate and deallocate kernel objects of the same size. (D) Signup and view all the answers

What is the MOST critical challenge in implementing a distributed shared memory (DSM) system with a high degree of consistency, considering the trade-offs between consistency, availability, and performance?

Minimizing network congestion and latency caused by frequent data transfers between nodes in the distributed system. (B) Signup and view all the answers

Assume a scenario where an OS implements a demand-paging system with a page replacement policy that aims to minimize page faults. If the system exhibits Belady's anomaly, what specific condition MUST be true?

The page replacement policy must be a non-stack-based algorithm, where the set of pages in memory is not a subset of the set with fewer frames. (D) Signup and view all the answers

In the context of file system design, what is the MOST significant limitation of using a contiguous allocation strategy for files in a modern operating system?

Difficulty in allocating sufficient contiguous space for growing files, leading to external fragmentation and allocation failures. (C) Signup and view all the answers

Consider a scenario where a file system employs a journaling technique to ensure data consistency after crashes. Which journaling approach provides the highest level of data integrity at the expense of performance?

Data journaling, where both metadata and the entire file data are written to the journal before being applied to the main file system. (C) Signup and view all the answers

What is the primary rationale for using the 'copy-on-write' (COW) technique in virtual memory management within modern operating systems?

To reduce the physical memory footprint by sharing identical pages between multiple processes until a write operation occurs. (D) Signup and view all the answers

In the context of I/O device management, what is the MOST significant advantage of using Direct Memory Access (DMA) over programmed I/O for data transfers between a peripheral device and system memory?

DMA transfers offload the CPU from managing the data transfer, allowing it to perform other tasks concurrently. (D) Signup and view all the answers

Consider an OS kernel implementing a capability-based security model. What inherent limitation does this model face when attempting to revoke access rights to a shared resource from a specific process?

The model inherently lacks a mechanism for tracking which processes hold capabilities for a given resource, complicating targeted revocation. (A) Signup and view all the answers

In the context of virtual machine (VM) technology, what is the primary advantage of using a Type 1 hypervisor (bare-metal hypervisor) compared to a Type 2 hypervisor (hosted hypervisor)?

Type 1 hypervisors have lower overhead and better performance because they run directly on the hardware. (D) Signup and view all the answers

Which of the following techniques provides the MOST effective defense against race conditions in concurrent kernel code, while minimizing performance overhead and maintaining code readability?

Using lock-free data structures with atomic operations to ensure synchronized access to shared data. (B) Signup and view all the answers

Consider a system that employs the Banker's Algorithm for deadlock avoidance. What critical assumption MUST hold true for the algorithm to guarantee deadlock-free resource allocation?

Processes must declare their maximum resource needs in advance before execution begins. (A) Signup and view all the answers

In the context of distributed operating systems, what is the MOST significant challenge in implementing a global clock synchronization mechanism that provides a consistent view of time across all nodes?

Compensating for variations in network latency and message propagation delays between nodes. (D) Signup and view all the answers

Which of the following architectural approaches offers the MOST robust solution for isolating and protecting sensitive kernel data structures from unauthorized access or modification by device drivers?

Using a microkernel architecture where device drivers run in user space and communicate with the kernel via message passing. (C) Signup and view all the answers

In the context of virtualized I/O, what is the primary role of a technique such as Single Root I/O Virtualization (SR-IOV) in enhancing the performance of network-intensive applications?

SR-IOV allows a single physical I/O device to be presented as multiple virtual devices to different VMs, reducing virtualization overhead. (A) Signup and view all the answers

Consider an operating system that uses a shadow page table mechanism for virtual memory management in a virtualized environment. What inherent challenge arises when attempting to maintain consistency between the guest OS's page tables and the shadow page tables managed by the hypervisor?

The hypervisor must intercept all guest OS page table updates, leading to increased overhead and potential performance bottlenecks. (A) Signup and view all the answers

In the context of file system integrity, which of the following techniques offers the MOST comprehensive protection against data corruption due to power failures, hardware errors, or software bugs?

Adopting an end-to-end data protection strategy that integrates data integrity checks throughout the entire storage stack. (A) Signup and view all the answers

What is the MOST critical consideration when designing a scheduler for a real-time operating system (RTOS) intended for safety-critical applications, such as those used in avionics or medical devices?

Guaranteeing that all tasks meet their deadlines with a high degree of certainty and predictability. (C) Signup and view all the answers

Flashcards

Operating System

An interface between the user and computer hardware.

OS Goal: Convenience

To make the computer system convenient to use.