2021 saw the consolidation of a number of kernel improvements, the introduction of new hardware support and much more. But while the year looks good for movement in the Linux kernel, the actual number of commits and lines is lower than ever.
The tech site phoronix has summarized the relevant 2021 Git development statistics. As of December 31, 2021, when running GitStats on the Linux kernel source tree, the repository had received 1,060,172 commits from about 243,000 different authors. The source tree currently consists of 32.2 million lines in 74.3k files.
The number of Linux kernel lines continues to grow at a fairly consistent rate, with new features emerging and extended hardware support reaching the mainline.
Despite some major feature additions and the introduction of hardware support in 2021, the kernel saw only 73.7k commits in 2021, down from 90.2k in 2020, 82.8k in 2019, 80.1k in 2018 and so on. The last time we saw less than 73.7k commits in a single year was in 2013, when we saw 70.9k. phoronix notes that this figure is partly due to the fact that there are only 5 major kernel releases in 2021, compared to 6 in some previous years. The extra merge window resulted in a large number of new commits; in addition, Linux 5.16 is scheduled for release in a few weeks, which will kick off the Linux 5.17 merge window in January.
In addition to the much lower than usual number of commits, the Linux kernel added 3.2 million lines and removed 1.3 million in 2021, down from 4 million lines added and 1.5 million lines removed in 2020.
As usual, Linus Torvalds remains the most prolific committer in the source tree, followed by David S. Miller, Arnd Bergmann, Christoph Hellwig, Lee Jones and Jakub Kicinski as the top five committers in the Linux kernel source tree. Long-time outstanding kernel contributors.
There were 4,421 different emails related to Linux kernel commits in 2021, down from 4,603 in 2020, but up from 4,383 in 2019.