create_systemd_service.txt

Packages we install normally reside at
/usr/bin (system related binaries in /usr/sbin)

Two locations where we can put Systemd packages 
/usr/lib/systemd/	(Create a directory system and put the foo.service in it)
/etc/systemd/system	(Put foo.service in it. Also can make directory foo.service.d and put 00-foo.conf to add features, make changes)
(/etc/systemd/system has precedence over /usr/lib/systemd/system)
00-foo.conf 
[Service]
ExecStart=
ExecStart=/usr/bin/stress --cpu 3 --io 3 --vm 3 --vm-bytes 32M  --timeout 9s

systemd-delta will tell which systemd configuration is used(will only tell either /usr/lib/systemd or /etc/systemd used). 

Slices are used for additional features. Add a file foo.slice inside /etc/systemd/system/ and declare this slice inside /etc/systemd/system/foo.service.d/00-foo.conf
foo.slice
[Unit]
Description= slice of stress from /etc/systemd/system/
[Slice]
CPUQuota=2%
(Then at the bottom of the file 00-foo.conf add following line)
Slice=foo.slice

Command 'systemctl daemon-reload' will reload configuration file of systemd unit