Linux is now 24 years old, and its community of developers, contributors and users shows no signs of shrinking. The annual “Who Writes Linux” report from the Linux Foundation was released today, and it includes many interesting nuggets about the people and companies who build Linux. Perhaps most interesting was the fact that the 3.15 kernel release cycle was said by the report to have been the busiest such cycle in the history of Linux.
Kernel 3.15 was released in June of 2014, and it included 13,722 patches, all integrated within the 70-day period in which it was in development. This was the largest patch cycle in the history of the kernel, and it averaged out to 8.17 patches integrated per hour. The average number of days between releases, now, is 66 days, down from 70 in 2013. The rate of change within the Linux kernel is increasing.
When Linux was first released in 1991, it was 10,000 lines of code. The kernel, as of release 3.18, now includes 18,997,848 lines of code. That code is spread across 47,986 files. In 2014, that code came from as many as 244 companies, and almost 1,500 individual developers.
Individual developers at the top of the list include H Hartley Sweeten of Vision Engraving & Routing Systems, perennial kernel developer Al Viro, and Takashi Iwai. Hartley, in particular, accounted for 2.2% of all kernel patches since the 2013 report was released.
Intel led this year’s corporate contributors list, with 10,108 changes made to the kernel by its employees. That accounted for 10.5% of the overall changes since 2013. Red Hat took the third spot with 8.4% of all changes. The No. 1 spot remains with unaffiliated developers, who accounted for 12.4% of all changes. Linaro, Samsung, IBM, SUSE and TI round out the top contributors, with Hartley’s contributions accounting for Vision Engraving Systems’ appearance in the Top 10.
One interesting statistic not necessarily included in previous years’ reports was information on new contributors. Last year, there were 1,963 new developers who contributed code to the kernel out of 4,171 developers overall working on the project. Chief among these new developers were the 1,418 brought in by the FOSS Outreach Program for Women.
Intel, Samsung, Google and IBM have all been bringing in new developers as well, with Intel topping the list at 147 new developers.
And, as usual, it’s still mostly Greg Kroah-Hartman running the show behind the scenes. While many other developers reviewed code contributed to the kernel, he accounted for 14.4% of all code sign-offs, almost double that of his nearest competitor, David S. Miller. Miller accounted for a hefty chunk of his own: 8.6% of all contributions were signed off by him. That was more than double the percentage put in by Miller’s nearest competitors, Mark Brown and Andrew Morton, who tied for third place.