Virtual memory in practice: Which statement best reflects the status of virtual memory usage in contemporary, widely used operating systems?

Introduction / Context:
Virtual memory underpins process isolation, protection, and flexible memory management. It is a foundational feature that enables multitasking, memory mapped files, and crash containment in modern systems.

Given Data / Assumptions:

• Mainstream desktop, server, and mobile operating systems are considered.
• Hardware support such as MMUs and TLBs is available on common CPUs.
• Virtual memory provides address translation and protection.

Concept / Approach:

All major commercial operating systems including Windows, macOS, mainstream Linux distributions, Android, and iOS implement virtual memory. They rely on paging, protection bits, and page replacement policies to present each process with an isolated virtual address space and to overcommit physical memory safely.

Step-by-Step Solution:

Verification / Alternative check:

Official OS documentation and architecture guides describe page tables, swap files, and memory protection as standard features, confirming ubiquity.

Why Other Options Are Wrong:

• Simple to implement: VM requires intricate hardware software cooperation.
• Less efficient in utilization of memory: VM improves effective utilization via demand paging and sharing; inefficiencies are workload dependent.
• Useful only when fast I O devices are not available: virtual memory depends on storage but is not limited by I O speed in definition.
• None of the above: incorrect because widespread use is true.

Common Pitfalls:

Confusing ease of use with ease of implementation; overlooking mobile OSes that also use full virtual memory mechanisms.

Final Answer:

used in all major commercial operating systems