I like to have my laptop encrypted in case I loose it or it get's stolen. This way I don't need to worry about the data I have stored on it. Since I'm having an SSD in my laptop it's necessary that I change some configs to have it supporting TRIM. TRIM is needed to have the SSD functioning correctly. I did this on Debian Jessie but it will most likely work with other distros as well.
We need to edit two files to get TRIM working. The first one is /etc/fstab. Simply add the discard parameter to the probably already present parameters.
/dev/mapper/volumegroup-root / ext4 noatime,nodiratime,errors=remount-ro 0 1
/dev/mapper/volumegroup-root / ext4 discard,noatime,nodiratime,errors=remount-ro 0 1
The second file we need to update is /etc/crypttab as before we simply need to add the discard parameter to the already presents parameter.
sda5_crypt UUID=e364d03f-[...]6cd7e none luks
sda5_crypt UUID=e364d03f-[...]6cd7e none luks,discard
To finally apply the new settings we have to run a single command:
sudo update-initramfs -u -k all
After that we're good to go and TRIM should work.