Who wrote systemd?

When it comes to systemd middleware, Lennart Poettering often takes the blame and has sole authorship attributed. But there are many more developers (git shows 593 authors in total) – missing their portion of berating, thus unappreciated and unhappy. Over the Winter Holidays I’ve run LWN's “who wrote” scripts to gather more insight into systemd’s developer base.

Developers with most changesets

Developers with the most changesets
Lennart Poettering Red Hat 7104 38.5%
Kay Sievers Red Hat 3711 20.1%
Zbigniew Jędrzejewski-Szmek hobbyist 1446 7.8%
Tom Gundersen Red Hat 948 5.1%
Greg KH Linux Foundation 624 3.4%
Michal Schmidt Red Hat 369 2.0%
Thomas Hindoe Paaboel Andersen GNOME 253 1.4%
David Herrmann hobbyist 233 1.3%
Martin Pitt Canonical 231 1.3%
Harald Hoyer Red Hat 207 1.1%
Dave Reisner Arch 148 0.8%

Lennart leads, but with less than 40% of all changesets. It seems he has written less than half of systemd. Sorry, Lennart :)
Kay Sievers earned second place mostly by maintaining udev for past couple of years. Majority of his commits were made while he was employed by Novell. Kay now works at Red Hat.
Third most active developer, Zbigniew Jędrzejewski-Szmek, commited less than 8% during the history of systemd. Nevertheless, Zbigniew steadily increases his productivity. OpenHub’s graphs for systemd shows he wrote 12% of changesets in 2014.
Clearly, systemd is driven by top five developers. There is a short drop afterwards. Eleventh person on list contributed less than 1% of all changesets. Red Hat as an affiliation appears few times. Further analysis is in the last section – ”Direct comitters”.

Developers with most changed lines

Developers with the most changed lines
Kay Sievers 565610 34.3%
Lennart Poettering 438513 26.6%
David Herrmann 94753 5.7%
Tom Gundersen 70541 4.3%
Greg KH 66951 4.1%
Zbigniew Jędrzejewski-Szmek 61506 3.7%
Michal Schmidt 16948 1.0%
Patrik Flykt 7386 0.4%

Per-line statistics looks a little bit different. Here Kay Sievers leads the pack with one-third of all lines changed. It is again mostly caused by the long history of udev, which was merged into systemd two and a half years ago – in April 2012.
Big individual counts by David Herrmann and Tom Gundersen can be attributed to non-init components they developed in systemd project. David wrote virtual console implementation, hacked on kdbus and logind. Tom created network configuration element of systemd.
Speaking of the networking, Patrik Flykt’s high position comes from refactoring ConnMan's DHCP client library into systemd-networkd. Recently, the library was utilised by NetworkManager 1.0.

Employers with the most hackers

Employers with the most hackers
Red Hat 46 7.1%
Novell 19 2.9%
Intel 14 2.2%
IBM 10 1.5%
Samsung 9 1.4%
Canonical 5 0.8%
Fujitsu 4 0.6%
ProFUSION 4 0.6%
Mandriva 3 0.5%
Dell 2 0.3%
Axis Communications 2 0.3%
Linux Foundation 2 0.3%
OLPC 2 0.3%
SGI 2 0.3%
HP 2 0.3%

While LWN’s scripts try to map each author to his parent company, it’s less robust than other kinds of statistics. People change employers while contributing to the same project. I do not see “hobbyists” in the table above, while over 10% of systemd has been created by them. Some authors contribute patches in their free-time, without relation to the employer. Nevertheless, it is interesting to see more or less recognizable company names in the list.

Direct commiters

There are 26 people with commit access to systemd git. Biggest group – 9 people – work for Red Hat. This is not surprising. RH have choosen systemd as a foundation for their enterprise offering. They had to build expertise and assure sustainable development. Sure way for that is to hire people contributing to systemd.

Next groups come in threes. Three people without clear company ties – I call them hobbyist. Three Debian/Ubuntu developers, with at least one person employed by Canonical. There are also three names from Intel.

Two developers can be associated with GNOME project. There are single developers from openSUSE, Mageia, Arch and CoreOS. There are also single committers from companies: Pantheon Systems and Aldebaran Robotics.

Bear in mind, above only talks about people with direct commit access to systemd’s git. There are companies contributing many patches through the mailinglist, but without dedicated commiter. I can recall few names from Samsung, which has contributed quite a number of patches. Tangentailly, there were only 2 patches from Jolla, which produces mobile phones and tablets with systemd onboard.


Red Hat pays the bills for biggest number of systemd authors. But please note, some of them were hired by RH specifically because of their earlier contributions to systemd. Community around project contains representatives from other major distributions, some of them even with direct commit access. Tom Gundersen, for example, did majority of his work as an Arch developer.

Some parts of systemd came from specific needs of external users. For example: CoreOS sponsored development of systemd-networkd; Pengutronix contributed watchdog support; Pantheon improved scalability with thousand of units, etc.

Archived comments:

quest 2014-12-30 22:03:35

Wow. What a long post!

First off. I didn't know Poettering wasnn't sole developer, but after his recent letter where he complained for people "trying to hire hitman to kill him", I think the other are somewhat lucky.

and second. "author" is only noun. It shouldn't be used as verb > http://www.thefreedictionary.com/author

zdz 2014-12-30 23:15:11

Thanks, I've replaced "author" with synonyms.

Linuxhippy 2014-12-30 23:56:46

As most of the time, Redhat is one of the few companies truly investing in open-source instead of just making bucks with it (canonical which e.g. has their desktop stuff under a license which makes it unuseable for anybody else)

Jristz 2014-12-31 01:07:33

@quest English is a language not normed, in contrast with spanish, french, bulgarian, etc; therefor any complain on what is correct and what is not in english grammar is either correct and wrong at same time, the main objetive is simply to be underestandable for the english readers, since without a norm solid writted like the examples I give, everithing that is underestandable is valid, even using author as a verb.

lRem 2014-12-31 01:15:57

> Google 0%

Impressive ;)

tg 2014-12-31 02:24:00

Nice post.

Minor comments: Dave Reisner works for Google (but I don't know if he contributes on their time) and David Herrmann works (now) for Red Hat.

Out of interest, how does the changed lines statistics handle non-code changes? If stuff like hwdb/*.hwdb and src/libsystemd-terminal/unifont.hex is included it would skew the numbers a lot I guess.

Jristz 2014-12-31 03:17:41

Dave Reiser is Arch developer, right, but they work indirectly to Google since the place where he work was buyed by google around 2009

Adam Williamson 2014-12-31 05:50:20

It's perfectly fine to use 'author' as a verb, e.g. "this changed was authored by Bob". Perfectly good English. I don't really like *any* free dictionary sites, but m-w.com is the best of a bad bunch, and it lists the verb use of 'author':


really, though, if you want a good dictionary, pay for an OED subscription; it's worth it.

Jono Loves Bacon 2015-01-01 23:05:32

>> Google 0%

>Impressive ;)

Why would you expect Google to contribute to this project?

zdz 2015-01-02 13:39:01

There are 34 patches from Filipe Brandenburger, using his @google.com email address. It's hard to say if those were made during his paid hours.

SDSSS 2015-01-02 18:06:05

Well, the top two developers (Poettering and Sievers) have been chided more than once for their attitude, in general, and their sloppiness, in particular.

Anonymous 2015-01-08 00:55:31

Where are you getting the employer data from? I didn't think the LWN database was generally available, and relying on the email domain is not reliable.


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