Who Writes Linux in 2013?

Both the pace of development and the volume of code continue to grow in the open-source Linux kernel.

The Linux kernel is at the heart of the open-source Linux operating systems, and it is developed by an ever-growing number of contributors, coming from a diverse group of companies. The Linux Foundation today released its annual "Who Writes Linux" report revealing trends in the state of Linux kernel development as well as who those contributors are and precisely how fast Linux is actually growing.

The report covers up to the Linux 3.10 long term support release; it does not include data on the 3.11 kernel that was released earlier this month.

The Linux 3.10 kernel includes 13,367 changes and was in development for 63 days. In contrast, the Linux 3.8 release, which was the first new Linux kernel of 2013, was in development for 70 days and included 12,394 changes.

The actual size of the Linux kernel is also growing. The Linux 3.10 kernel is made up of 16,961,031 lines of code, and the Linux 3.8 kernel, which was released at the beginning of the year, had 16,422,416 lines of code. In contrast, the Linux 3.0 kernel, which was released in July of 2011, had only 14,651,135 lines of code.

"Every year, since 2003 when I started keeping these numbers, I have said, 'Wow, we are going so fast, there's no way we can keep rate of change and number of developers and companies going,'" Linux kernel developer Greg Kroah-Hartman told eWEEK. "And every year, that number has increased. So I'm a bad judge of these things."

While the numbers in the recent report show an increasing Linux kernel size, Kroah-Hartman noted that development time, as measured by development days for a release, has been really constant over the long term. The time has been slightly shortened as Linux kernel developers have adapted the development process and fine-tuned tools.

"Rate of change, and number of patches accepted, keeps going up, as our community size has increased," he added.

Linus Torvalds

The Linux community began with a newsgroup message from developer Linus Torvalds some 22 years ago. Torvalds remains a key figure in the Linux development community as the person who formally releases new mainline Linux kernels. When it comes to actual code, however, Torvalds' contributions no longer rank among the top 100 Linux kernel developers.

Torvalds currently ranks 101st on the latest "Who Writes Linux" report for number of patches generated from the Linux 3.3 to the Linux 3.10 kernel releases. Topping the list is Linux kernel developer H Hartley Sweeten with 2.3 percent of changes. Sweeten is followed by kernel developer Mark Brown, who contributed 1.5 percent of changes.

In terms of corporate sponsors of Linux, Red Hat leads the list, with its developers contributing 10.2 percent of all changes. Red Hat is followed by chip vendors Intel at 8.8 percent and Texas Instruments at 4.1 percent. IBM is credited with contributing 3.1 percent of code changes, Google comes in at 2.4 percent and Oracle is at 1.3 percent.


A common question in the Linux community is when and if kernel development will ever hit an upper limit and plateau. Kroah-Hartman commented that he always thinks kernel development has plateaued, but the reality is that every year for the past decade, Linux kernel development has grown.

"We've broken all the rules as to how to develop a software project and have created something that has never been done before, so all of this is uncharted waters for everyone," Kroah-Hartman said. "All we can do is watch and keep on top of issues and work to smooth out any rough spots in our development process as they come up."

Sean Michael Kerner is a senior editor at eWEEK and InternetNews.com. Follow him on Twitter @TechJournalist.

Sean Michael Kerner

Sean Michael Kerner

Sean Michael Kerner is an Internet consultant, strategist, and contributor to several leading IT business web sites.