I found an interesting post on LWN.net that analyzed the Linux 2.6.20 source code to discover who contributed the most code and what company they work for. It struck me that the Linux development hierarchy is a lot like traditional software development.

The top 20 people contribute about 50% of the code. I think most large software projects are like that. The "code gods" pump out the core code while hundreds, sometimes thousands, of detail coders and testers work out the rest.

LWN.net took several approaches to looking at the contributors such as; lines of code changed, changesets, lines removed, and signoffs. Lines of code changed seems to be the most reasonable measure of contribution, although each measure is open to interpretation. A little over 48% of the code lines changed were contributed by 20 individuals.

Developers with the most changed lines Jeff Garzik 20712 6.0% Patrick McHardy 15024 4.3% Jiri Slaby 13917 4.0% Avi Kivity 11726 3.4% Andrew Victor 9710 2.8% Amit S. Kale 9537 2.7% Stephen Hemminger 9120 2.6% Geoff Levand 8396 2.4% Michael Chan 8307 2.4% Chris Zankel 8099 2.3% Mauro Carvalho Chehab 7390 2.1% Adrian Bunk 6138 1.8% Yoshinori Sato 5232 1.5% Al Viro 4981 1.4% Benjamin Herrenschmidt 4588 1.3% Thierry MERLE 4549 1.3% Dan Williams 4516 1.3% Jonathan Corbet 3924 1.1% Gerrit Renker 3857 1.1% Jiri Kosina 3805 1.1%

LWN.net next looked at who was paying these contributors. Meaning, the domain name of the company they worked for. It was not possible to get a domain name in all cases. But, here are the results from LWN.net.

Top lines changed by employer (Unknown) 66154 19.0% Red Hat 44527 12.8% (None) 38099 11.0% IBM 25244 7.3% Astaro 15306 4.4% Linux Foundation 13638 3.9% Qumranet 12108 3.5% Novell 11930 3.4% Intel 11652 3.4% SANPeople 9888 2.8% NetXen 9607 2.8% Sony 8497 2.4% Broadcom 8349 2.4% Tensilica 8195 2.4% Nokia 5581 1.6% MontaVista 4394 1.3% University of Aberdeen 4324 1.2% LWN.net 3975 1.1% Secretlab 3370 1.0% HP 3211 0.9%

While "unknown" and "none" accounted for 30% of the changes, the remaining 18 companies accounted for almost 60% of the code lines contributed. It is possible that some significant percentage of the "unknown" and "none" actually worked for some of these companies, but made their contributions from home.

Where is Google? Not surprisingly, Red Hat, IBM, and Novell were big contributors. But where is Google? They certainly use Linux and lots of Open Source software, but why don't they show up as even 1% contributors?

The Long Tail of software development - It would be interesting to see the distribution of contributors for the remaining 50% of the code. My guess is that there is a very long tail of small contributors. Again, not unlike lots of big traditional software development projects.

How many Open Source users actually make changes to the source code? I recently spoke at a Fortune 500 CIO conference. During my speech I did a real time poll of the audience of CIOs. The results confirmed my gut feel for how the market really works. Here are the questions and the results.

How many use Windows Server? 100%

How many use Linux? 45%

How many use both? 45%.

How many of you have made changes to the source code? 8%

Very few Open Source users ever touch the source code. So is it really about the source code?

A small number of companies contribute most of the code to Open Source development, so is it really about the community?

There are lots of free open source distributions of Linux, various databases, application servers, etc. Yet, Microsoft, Oracle, and BEA do pretty well in each market. Is it really about the price?

Everyone has an opinion, but I haven't seen any real survey data that covers these questions. Have any of you seen studies on this?

My real time survey of the CIO audience confirmed my belief that Open Source users are not zealots. They have pragmatic reasons for choosing Linux for some jobs and Windows for others. Understanding all those reasons will take more study.

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