virtual memory

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virtual memory

A computer uses virtual memory to run multiple programs at once.

Definition

Noun: 1. A memory management technique: A system that allows a computer to compensate for shortages of physical random-access memory (RAM) by temporarily transferring data from RAM to disk storage. 2. An illusion of abundant memory: The addressable storage space available to a user or program that appears to be RAM but is actually a combination of physical RAM and secondary storage (like a hard disk or SSD).

Usage
  • Virtual memory is a critical component of modern operating systems, allowing them to run more applications than could fit in physical RAM alone.
  • When a system is low on physical RAM, it uses virtual memory to store less-active data, freeing up RAM for active tasks.
  • The size and management of the virtual memory space (often controlled by a paging file or swap space) can affect a computer's performance.
Examples
  • "The application crashed because it exhausted the available virtual memory."
  • "To improve performance on your old computer, you might try increasing the virtual memory allocation."
  • "The operating system uses virtual memory to give each program the illusion that it has a large, contiguous address space."
Advanced Usage
  • Demand Paging: A common virtual memory implementation where data is moved into physical RAM only when it is needed (or "paged in" upon access).
  • Thrashing: A performance degradation that occurs when a system spends more time swapping data between RAM and disk for virtual memory than executing useful work.
  • Virtual Address Space: The range of memory addresses that a program can use, made possible by virtual memory, which is independent of the actual physical RAM layout.
Variants and Related Words
  • Swap Space / Paging File: The area on a disk used to store data swapped out from RAM as part of virtual memory management.
  • Physical Memory (RAM): The actual hardware memory chips, which virtual memory extends.
  • Memory Management Unit (MMU): The hardware component that handles the translation of virtual addresses to physical addresses.
Synonyms
  • Paged Memory: (Technical) Emphasizes the implementation method where memory is divided into fixed-size blocks called pages.
  • Swap Memory: (Common usage) Highlights the action of "swapping" data to disk, though technically this is the mechanism, not the overall concept.
Related Phrases
  • To page out / swap out: The action of moving data from RAM to the disk to free up physical memory.
  • To page in / swap in: The action of moving data from the disk back into RAM when it is needed.
  • Virtual memory manager: The part of the operating system responsible for implementing virtual memory.
virtual memory

A computer uses virtual memory to run multiple programs at once.

Noun
  1. (computer science) memory created by using the hard disk to simulate additional random-access memory; the addressable storage space available to the user of a computer system in which virtual addresses are mapped into real addresses

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