====== All about swap ======

Who use mostly swap memory:
<code bash>
for file in /proc/*/status ; do awk '/VmSwap|Name/{printf $2 " " $3}END{ print ""}' $file; done | sort -k 2 -n -r | head
</code>

====== Sort procesess by memory ======
<code bash>
ps aux --sort -rss | head
</code>

====== Count php-fpm used memory ======
<code bash>
ps aux | grep php-fpm | grep -v grep | awk '{sum+=$6} END {print sum}'
</code>

====== Release swap ======
<code bash>
sudo bash -c 'swapoff -a && swapon -a' &
</code>

====== SWAPFILE creation ======

First prepare file for swap:
<code bash>
fallocate -l 1024M /swapfile
</code>
or
<code bash>
dd if=/dev/zero of=/swapfile bs=1M count=1024
</code>
Change file permission:
<code bash>
chmod 600 /swapfile
</code>
Make swap on swapfile:
<code bash>
mkswap /swapfile
</code>
Turn on swap:
<code bash>
swapon /swapfile
</code>
Add to fstab - /etc/fstab
<code bash>
/swapfile none swap defaults 0 0
</code>