Survey of Linux kernel developers

I get mail from folks about my book, the device driver I wrote for Linux, and about articles I’ve written for Linux Journal. A few months ago I got one which said, in part:

I can only hope his laughter was kindly. The opinions expressed by his boss weren’t the first I’ve heard of that sort. Nor, I fear, will this be the end of it. Nonetheless, I decided to take a shot at confronting these claims.

I had suspicions that Linux contributors are a bright, experienced and well-educated bunch of folks. The discussions in the various Linux newsgroups and mailing lists aren’t lightweight, nor is the resulting operating system. My “feel” of the operating system is that it’s based on a lot of mature judgments and there is some theoretical grounding in what’s being done.

Credits

I gathered up a list of contributors (from /usr/src/linux/CREDITS) and sent off 241 notes. Partial text of this note is shown in the sidebar, “Letter to Contributors”. I sent my notes with some trepidation—I didn’t want to bother folks while they were working on important projects, and I feared a lack of response.

Letter to Contributors

I needn’t have worried. So far I’ve received 103 replies, many of which have included a few words of encouragement. It seems that I wasn’t the only one who wanted to respond to unjustified complaints about Linux. (Another 29 notes were returned with address errors. I hope to see corrections to the CREDITS file.)

I’m conducting a brief survey of fellow contributors to the Linux kernel.
…
It seems that products developed by students, no matter how well designed and implemented and no matter how qualified the students, are regarded as having lower quality.
…
But that’s not really the case with Linux. Almost from the start it has been more than just a school project.
…
I’d like to investigate the educational backgrounds and current work situations of the contributors.

The level of response was the first piece of good news. The second was that I’ve been stunned by how strong the development team is with regards to both credentials and experience.

From these replies I found:

That’s got to totally demolish the image of college hackers—at least the sophomore part of it. I figured I was an exception when I started working on the Cyclades driver while avoiding rewriting my dissertation. I thought, once folks were awarded a Ph.D., they would be busy with research, teaching or some other interest. I guess Linux development may be the doctor’s favorite hobby.

When I offered an earlier summary of these results, my correspondent reported that his boss wisely intoned, “those folks are all academia and none of them have ever tried to run a business.”

I had sort of expected a comment along those lines and fortunately asked a few more questions in my survey. One hundred of the replies also reported the number of years spent programming or doing system design.

More than a few of us were programming before the integrated circuit came into general use. (Perhaps a mixed blessing—some of us may still suffer from post-FORTRAN syndrome.)

As I noted earlier, I have also felt that Linux has benefitted from a broad experience in its developer base. Linux may be a first operating system for a lucky few, but almost everyone (all but three) claimed to be at least a skilled user of another operating system. Eighty-three were skilled users of several other operating systems.

Nor was their contribution to the Linux kernel the first of that sort. Twenty have contributed to another operating system and another twenty-two have contributed to several other operating systems. One reported:

Finally, I wanted to know if the contributors were “doing Linux” in their careers. Eighty-two said their current employment was based on their computer skills. It was interesting to note that over a third reported their current employment supported or relied on their Linux development efforts. Sadly, two reported they were currently unemployed, but one of those also noted that he was “voluntarily unemployed to have time to put my life in better order.”

Perhaps one significant difference between Linux development and academic or commercial development is the duration of personal interest. In an academic setting, a student typically has one term, or at most one year, to work on any given program. When programmers leave a company, support is picked up by someone who has no sense of what has gone before. There is greater continuity in the Linux community because of the nature of submission and distribution. No matter what is happening at school or where one works day to day, contributors can keep in touch with progress on their piece of the puzzle. One person noted, “Personally, I did start my code in school, but that does not stop me from maintaining it now.”

There are some other issues which weren’t addressed by my survey. Although it might not seem relevant to quality and performance, a person’s interest has a great deal to do with the outcome—it leads to a distinction between “craftsmanship” and “work product”. Another person noted:

Another motive, akin to what pushed me to first join the effort, was shared by another respondent who said, “When I wrote [my code] for the Linux kernel I was working at [my former employer]. Linux use there was extensive, and I wanted to give something back.”

Motivation leads to the final and most significant issue—one which cannot be examined by a developer survey.

In a world driven by marketing, image is the basis for purchasing decisions. Even if a good image could be established for Linux by listing credentials or tabulating years of experience, I’d be reluctant to shift to that level. I’d much rather see acceptance and popularity for Linux based on quality and performance.

Even though I hadn’t asked specific questions on this topic, a few people offered comments. One note seemed to identify, however obliquely, what may be the key to Linux’s success.

Developing on this theme, another wrote:

We not only need to bring the CREDITS file into an accurate state, but we also need to acknowledge the thousands who have contributed to Linux by using it and sharing their discoveries—good or bad—with others.

Peter H. Salus reports the UNIX philosophy in A Quarter Century of UNIX as:

I’d like to close by adding another entry, suggested by UNIX and dominant in Linux:

I just received a note from the person who sparked the original survey. He reports:

It looks like we’ve won one more away from the dark side.