The Linux Foundation has updated its April 2008 study on Linux kernel development, the one called "Linux Kernel Development: How Fast is it Going, Who is doing it and Who is Sponsoring it?".

The updated study found that since April 2008 there's been a 10% increase in the number of developers contributing to each kernel release and that a net of 2.7 million lines of code have been added.

This level of activity has resulted in an average of 5.45 patches being accepted an hour, an increase of 42%.

It attributes some of the accelerated pace of development to new demand for Linux in emerging markets, such as netbooks, auto and energy, as well as to the new linux-next tree, a staging area for the next kernel cycle that enables the development process to scale more rapidly.

It also says that every Linux kernel is being developed by nearly 1,000 developers working for more than 200 different corporations. More than 70% of the contributions come from developers working for companies such as Red Hat, IBM, Novell, Intel, Oracle and Fujitsu.

Red Hat, Google, Novell, Intel and IBM top the list of companies that employ developers who are reviewing and approving Linux development.

An average of 10,923 lines of code is added a day and an average of 5,547 lines is removed every day.

See http://www.linuxfoundation.org/publications/whowriteslinux.pdf.