Swappiness controls the tendancy the kernel wishes to swap.
Even with free memory the kernel may swap.
100 means aggressively swap 0 means wait until the last minute to swap
To check current swappiness
cat /proc/sys/vm/swappiness
To change it live
sudo sysctl vm.swappiness=0
To change it after reboot
sudo vim /etc/sysctl.conf
Change the value of vm.swappiness if it doesn't exist then add it to the bottom:
vm.swappiness=0