Editing Memory paging (section)

=====Swap death=====
When the system memory is highly insufficient for the current tasks and a large portion of memory activity goes through a slow swap, the system can become practically unable to execute any task, even if the CPU is idle. When every process is waiting on the swap, the system is considered to be in ''swap death''.<ref>{{cite web |url=http://lkml.iu.edu/hypermail//linux/kernel/9805.2/0707.html |title=swap death (as in 2.1.91) and page tables |author=Rik van Riel |date=1998-05-20 |url-status=live |archive-url=https://web.archive.org/web/20171229195527/http://lkml.iu.edu/hypermail//linux/kernel/9805.2/0707.html |archive-date=2017-12-29 }}</ref><ref>{{cite book|author=Kyle Rankin|title=DevOps Troubleshooting: Linux Server Best Practices|url=https://books.google.com/books?id=icPyQDU3xD4C&pg=PT159|year=2012|publisher=Addison-Wesley|isbn=978-0-13-303550-6|page=159|url-status=live|archive-url=https://web.archive.org/web/20171229195527/https://books.google.com/books?id=icPyQDU3xD4C&pg=PT159|archive-date=2017-12-29}}</ref>

Swap death can happen due to incorrectly configured [[memory overcommitment]].<ref>{{cite web|url=https://www.win.tue.nl/%7Eaeb/linux/lk/lk-9.html|author=Andries Brouwer|title=The Linux kernel: Memory|url-status=live|archive-url=https://web.archive.org/web/20170813052950/http://www.win.tue.nl/~aeb/linux/lk/lk-9.html|archive-date=2017-08-13}}</ref><ref>{{cite web|url=https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/6/html/Performance_Tuning_Guide/s-memory-captun.html|title=Capacity Tuning|author=Red Hat|url-status=live|archive-url=https://web.archive.org/web/20170723214620/https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/6/html/Performance_Tuning_Guide/s-memory-captun.html|archive-date=2017-07-23}}</ref><ref>{{cite web|url=https://iainvlinux.wordpress.com/2014/02/16/memory-overcommit-settings/|title=Memory overcommit settings|date=16 February 2014|url-status=live|archive-url=https://web.archive.org/web/20170531182419/https://iainvlinux.wordpress.com/2014/02/16/memory-overcommit-settings/|archive-date=2017-05-31}}</ref>

The original description of the "swapping to death" problem relates to the [[X Window System protocols and architecture#Client–server model and network transparency|X server]]. If code or data used by the X server to respond to a keystroke is not in main memory, then if the user enters a keystroke, the server will take one or more page faults, requiring those pages to read from swap before the keystroke can be processed, slowing the response to it.  If those pages do not remain in memory, they will have to be faulted in again to handle the next keystroke, making the system practically unresponsive even if it's actually executing other tasks normally.<ref>{{cite web|url=http://tech-insider.org/linux/research/1993/0210.html|title=swapping to death|date=1993-02-10|author=Peter MacDonald|url-status=live|archive-url=https://web.archive.org/web/20170328080649/http://tech-insider.org/linux/research/1993/0210.html|archive-date=2017-03-28}}</ref>