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77 lines
1.7 KiB
Markdown
77 lines
1.7 KiB
Markdown
# Swap
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## Table of contents <!-- omit in toc -->
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1. [TL;DR](#tldr)
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1. [Swappiness](#swappiness)
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1. [Swapfile](#swapfile)
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1. [Further readings](#further-readings)
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## TL;DR
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```sh
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# show the swap usage
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swapon --show
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free -h
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# enable or disable a swap partition or file
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sudo swapon /root/swapfile
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sudo swapoff LABEL=swap
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sudo swapoff /dev/sda2
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# enable or disable *all* swap partition or file
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sudo swapon -a
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sudo swapoff --all
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# check what processes are swapping
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# see the "si" (swap in) and "so" (swap out) columns
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vmstat
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vmstat --wide 1
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```
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## Swappiness
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```sh
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# check the current value
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sysctl vm.swappiness
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# change the current value
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sudo sysctl vm.swappiness=10
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sudo sysctl -w vm/swappiness=5
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# persistent configuration
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echo 'vm.swappiness=10' | sudo tee -a /etc/sysctl.conf
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echo 'vm.swappiness = 5' | sudo tee -a /etc/sysctl.d/99-swappiness.conf
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```
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## Swapfile
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```sh
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# add a swapfile
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sudo fallocate -l 1G /swapfile # or sudo dd if=/dev/zero of=/swapfile bs=1024 count=1048576
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sudo chmod 600 /swapfile
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sudo mkswap /swapfile
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sudo swapon /swapfile
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echo '/swapfile swap swap defaults 0 0' | sudo tee -a /etc/fstab
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# remove a swapfile
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sudo swapoff -v /swapfile
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sudo sed -i.bak '/\/swapfile/d' /etc/fstab
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sudo rm /swapfile
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```
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## Further readings
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- [create a linux swap file]
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- [How to reload sysctl.conf variables on Linux]
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- [How to empty swap if there is free RAM]
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<!--
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References
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-->
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<!-- Others -->
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[create a linux swap file]: https://linuxize.com/post/create-a-linux-swap-file/
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[how to reload sysctl.conf variables on linux]: https://www.cyberciti.biz/faq/reload-sysctl-conf-on-linux-using-sysctl/
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[how to empty swap if there is free ram]: https://askubuntu.com/questions/1357/how-to-empty-swap-if-there-is-free-ram#1379
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