World Library  
Flag as Inappropriate
Email this Article

Memory overcommitment

Article Id: WHEBN0041961615
Reproduction Date:

Title: Memory overcommitment  
Author: World Heritage Encyclopedia
Language: English
Subject: Memory virtualization, Hardware virtualization, Virtual machine
Publisher: World Heritage Encyclopedia

Memory overcommitment

Memory overcommitment is a concept in computing that covers the assignment of more memory to virtual computing devices than the physical machine they are hosted on actually has. This is possible because virtual machines do not necessarily use as much memory at any one point as they are assigned, creating a buffer. If four virtual machines each have 1GB of memory on a physical machine with 4GB of memory, but those virtual machines are only using 500MB, it is possible to create additional virtual machines that take advantage of the 500MB each existing machine is leaving free.[1] Memory swapping is then used to handle spikes in memory usage. The disadvantage of this approach is that memory swap files are slower to read from than 'actual' memory, which can lead to performance drops.[2]

While memory overcommitment is usually talked about in the context of virtualization, it is actually a generalised concept; Windows NT contained overcommitment features, as do most modern generalised operating systems,[3] including the Linux kernel.[4]


  1. ^
  2. ^
  3. ^
  4. ^
This article was sourced from Creative Commons Attribution-ShareAlike License; additional terms may apply. World Heritage Encyclopedia content is assembled from numerous content providers, Open Access Publishing, and in compliance with The Fair Access to Science and Technology Research Act (FASTR), Wikimedia Foundation, Inc., Public Library of Science, The Encyclopedia of Life, Open Book Publishers (OBP), PubMed, U.S. National Library of Medicine, National Center for Biotechnology Information, U.S. National Library of Medicine, National Institutes of Health (NIH), U.S. Department of Health & Human Services, and, which sources content from all federal, state, local, tribal, and territorial government publication portals (.gov, .mil, .edu). Funding for and content contributors is made possible from the U.S. Congress, E-Government Act of 2002.
Crowd sourced content that is contributed to World Heritage Encyclopedia is peer reviewed and edited by our editorial staff to ensure quality scholarly research articles.
By using this site, you agree to the Terms of Use and Privacy Policy. World Heritage Encyclopedia™ is a registered trademark of the World Public Library Association, a non-profit organization.

Copyright © World Library Foundation. All rights reserved. eBooks from World eBook Library are sponsored by the World Library Foundation,
a 501c(4) Member's Support Non-Profit Organization, and is NOT affiliated with any governmental agency or department.