Benefits of TPS for modern Windows

Benefits of TPS for modern Windows

Q. Will Transparent Page Sharing provide much benefit for modern Windows operating systems?

A. Transparent Page Sharing (TPS) works by finding pages of memory that contain the same content and then removing the duplicate pages, single-instance storing the page and therefore saving memory. TPS works very well for small memory pages which are 4 KB in size as the chances of finding 4 KB memory pages with the same content are good. Modern operating systems, both Windows and Linux, are moving more to large memory pages which are 2 MB in size which greatly reduces the benefit of TPS since the chance of finding 2 MB memory pages with the same content are much less. The scenario where TPS still provides benefit is where a VM has a large amount of zeroed pages which will be the case if a VM has been over-allocated memory such as desktop VDI deployments.

Note that TPS between VMs is disabled by default in ESX 5.0 and above because of a possible, while highly unlikely, attack as documented at http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=2080735.

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