Operating Systems Quiz

During runtime, an OS needs to decide which page to remove when memory is full. One technique is LRU, which uses history of access. How does LRU compare with FIFO in terms of performance and overhead?

• FIFO is more accurate

• LRU always faults more

• LRU is more effective but complex

• FIFO is based on future use

A user configures their system to use a very small page size in virtual memory settings. They notice that more pages are being loaded than before. What could be the trade-offs involved in using smaller pages?

• More TLB hits

• Lower fragmentation and more overhead

• Better CPU utilization

• Fewer page faults

In a virtual memory setup, the system allows shared memory pages between processes. How does this feature enhance system efficiency and what precautions must be taken to ensure consistency?

• It increases isolation

• Pages are never duplicated

• Shared pages save memory but need synchronization

• Every process has its own copy

A virtual address is passed to the OS during execution. The system uses paging with a TLB. If the required entry is not found in the TLB, the system checks the page table. What is this process known as, and what's the performance implication?

• Cache hit

• TLB miss and page walk

• Segment fault

• Stack overflow

A device that employs a rotating platter to perform data read and write operations is the Hard Disk Drive (HDD). Its operation involves spinning magnetic disks and moving read/write heads to access data.

• SSD

• RAM

• Magnetic disk

• Cache memory

During program execution, if a needed page is missing from main memory, the system experiences a page fault. This initiates a sequence wherein the operating system fetches the page from disk and loads it into available memory space.

• A segmentation fault occurs

• A page hit happens

• A page fault is triggered

• The process is terminated

A reliable page replacement algorithm employed in memory management is Least Recently Used (LRU). This technique optimizes performance by discarding the least accessed pages when new pages need to be loaded into memory.

• FIFO

• LRU

• Optimal

• All of the above

Thrashing results from an operating system's overreliance on swapping pages due to high memory contention. This leads to excessive disk I/O and reduced processing capacity, significantly impairing system performance.

• High CPU utilization

• Low I/O requests

• Excessive page faults

• Lack of CPU scheduling

The working set model defines the concept of maintaining a process's most recently and frequently used pages in memory. It serves as a dynamic measure to balance memory allocation and reduce page faults.

• The total virtual memory used by all processes

• The set of pages actively used by the process during a time window

• The swap memory size

• The main memory size

Hard Disk Drives (HDDs) are known for their use of spinning platters and movable read/write heads, enabling them to store and retrieve data mechanically as opposed to the flash-based storage used in SSDs.

• SSD

• RAM

• Magnetic disk

• Cache memory