Linux Kernel Development: How Fast it is Going, Who is Doing It, What They are Doing, and Who is Sponsoring It 
The kernel which forms the core of the Linux system is the result of one of the largest cooperative software projects ever attempted. Regular 2-3 month releases deliver stable updates to Linux users, each with significant new features, added device support, and improved performance.
The rate of change in the kernel is high and increasing, with over 10,000 patches going into each recent kernel release. These releases each contain the work of over 1000 developers representing around 200 corporations.
Since 2005, over 5,000 individual developers from nearly 500 different companies have contributed to the kernel. The Linux kernel, thus, has become a common resource developed on a massive scale by companies which are fierce competitors in other areas.
A number of changes have been noted since this paper was first published in 2008:
• We have seen a roughly 10% increase in the number of developers contributing to each kernel release
• The rate of change has increased significantly; the number of lines of code added to the kernel
each day has nearly tripled.
• The kernel code base has grown by over 2.7 million lines.
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