Linux Kernel Development: How Fast it is Going, Who is Doing It, What They are Doing, and Who is Sponsoring It 
As documented in 2009 the Linux community saw, with the release of 2.6.30, a peak in the lines of code added. This can largely be attributed to significant new features being added to the kernel, most notably the first additions of Btrfs, perf and ftrace, as well as the peak of the inflow from the Linux-staging tree that had been happening for some time.
This update shows a slightly different picture. The number of commits peaked with the 2.6.30 release; the number of commits for 2.6.35 was 18% lower. Most other metrics have fallen as well. In short, we see a step back from the frenzied activity of 2.6.30 even though the number of
developers involved has fallen only slightly since its peak in 2.6.32.
The numbers in this edition of the paper reflect the natural development cycle of an operating system that had major pieces added/changed in the previous year. Of course the Linux kernel community is still hard at work and growing. In fact, there have been 1.5 million lines of code added to the kernel since the 2009 update.
The data in this year’s update also shows a good showing of new players in the Linux kernel development space from the world of mobile/consumer electronics and embedded technology (and their suppliers). This is a healthy development and not surprising given the growth of Linux usage in embedded devices.
Read the full report: