Andrew McGlashan writes:
At 2:45 he says that you tell systemd what the dependencies of things are, and systemd figures out at boot time what to do. Hey, couldn't that be done with a make file, with a whole less code and fanfare? LOL, make boot.
This is called startpar, and SuSE already wrote it, in 2003. Debian 7 uses it by default. Here's my halt dependency DAG: # cat /etc/init.d/.depend.stop TARGETS = quotarpc mdadm busybox-syslogd smartmontools busybox-klogd urandom hwclock.sh quota sendsigs umountnfs.sh networking umountfs umountroot mdadm-raid mdadm-waitidle live halt reboot quota: quotarpc sendsigs: quotarpc quota mdadm busybox-klogd busybox-syslogd umountnfs.sh: quotarpc quota sendsigs busybox-klogd busybox-syslogd networking: umountnfs.sh umountfs: quotarpc quota networking umountnfs.sh mdadm busybox-klogd busybox-syslogd hwclock.sh urandom umountroot: umountfs mdadm-raid: umountfs mdadm mdadm-waitidle: umountroot live: umountroot halt: live umountroot mdadm-waitidle reboot: live umountroot mdadm-waitidle It's invoked with these args by default: /etc/init.d/rc:95: eval "$(startpar -p 4 -t 20 -T 3 -M $1 -P $previous -R $runlevel)" That is, it runs up to four jobs per CPU in parallel. "The -M option switches startpar into a make(1) like behaviour." You may also want to look at minit / cinit.