Some 5.16 kernel development statistics

The 5.16 kernel was released on January 9, as expected. This development cycle incorporated 14,190 changesets from 1,988 developers; it was thus quite a bit busier than its predecessor, and fairly typical for recent kernel releases in general. A new release means that the time has come to have a look at where those changes came from.

The 1,998 developers contributing to 5.16 was the second-highest number ever, with only 5.13 (with 2,062 developers) being higher. This time around, 296 developers contributed their first change to the kernel, which is at the high end of the typical range. The most active developers in this cycle were:

Most active 5.16 developers

By changesets Michael Straube 286 2.0% Cai Huoqing 232 1.6% Jakub Kicinski 200 1.4% Christoph Hellwig 158 1.1% Bart Van Assche 157 1.1% Krzysztof Kozlowski 140 1.0% Mauro Carvalho Chehab 130 0.9% Pavel Begunkov 122 0.9% Thomas Gleixner 117 0.8% Alex Deucher 112 0.8% Matthew Wilcox 108 0.8% Geert Uytterhoeven 103 0.7% Jani Nikula 94 0.7% Ian Rogers 91 0.6% Arnd Bergmann 88 0.6% Ville Syrjälä 86 0.6% Mark Brown 85 0.6% Martin Kaiser 85 0.6% Colin Ian King 82 0.6% Jens Axboe 80 0.6%

By changed lines Ping-Ke Shih 91116 11.4% Zhan Liu 34501 4.3% Nick Terrell 28611 3.6% Sameer Pujar 15121 1.9% Johan Almbladh 13901 1.7% Thomas Bogendoerfer 11591 1.4% Michael Straube 9014 1.1% Dmitry Baryshkov 7836 1.0% Srinivas Kandagatla 7663 1.0% Larry Finger 7586 0.9% Prabhakar Kushwaha 6261 0.8% Jakub Kicinski 5796 0.7% Fangzhi Zuo 5765 0.7% Alex Deucher 5627 0.7% Peter Zijlstra 5448 0.7% Jani Nikula 5287 0.7% Simon Trimmer 5249 0.7% Shawn Guo 5152 0.6% Tony Lindgren 5020 0.6% Derek Fang 4973 0.6%

The most prolific contributor of changesets for 5.16 was Michael Straube, who worked almost exclusively on the r8188eu wireless network adapter driver in the staging tree; that driver has now received 755 changes since being merged for the 5.15 release. Cai Huoqing contributed clean-up patches in many areas of the kernel, Jakub Kicinski made improvements throughout the networking subsystem, Christoph Hellwig continues his refactoring work in the block and filesystem layers, and Bart Van Assche reworked much of the SCSI subsystem code.

In the lines-changed column, Ping-Ke Shih came out on top with the addition of the Realtek rtw89 driver; unlike many past Realtek drivers, this one skipped the staging tree and landed directly under drivers/net. Zhan Liu contributed exactly two patches adding yet another set of amdgpu header files. Nick Terrell updated the kernel's zstd compression module, Sameer Pujar added a set of NVIDIA Tegra sound drivers, and Johan Almbladh added eBPF JIT compilers for the 32- and 64-bit MIPS architectures. It's worth noting that there were relatively few large code removals in 5.16 (the biggest was the removal of Netlogic MIPS support by Thomas Bogendoerfer), so the kernel as a whole grew by 422,000 lines.

The kernel project depends on its testers and reviewers as much as it depends on its developers. For the 5.16 cycle, the contributors with the most test and review credits were:

Test and review credits in 5.16
Tested-by Daniel Wheeler 153 14.8% Sandeep Penigalapati 34 3.3% Tony Brelinski 25 2.4% Deren Wu 24 2.3% Gurucharan G 22 2.1% Sohaib Mohamed 22 2.1% Konrad Jankowski 20 1.9% Alexei Starovoitov 16 1.5% Mark Wunderlich 14 1.4% John Garry 13 1.3% Christian Zigotzky 13 1.3% Fuad Tabba 12 1.2% Shawn Guo 12 1.2% Geert Uytterhoeven 10 1.0% Ferry Toth 10 1.0%	Reviewed-by Christoph Hellwig 202 3.2% Rob Herring 194 3.0% Hans de Goede 119 1.9% Pierre-Louis Bossart 104 1.6% Stephen Boyd 100 1.6% David Howells 83 1.3% David Sterba 80 1.2% Jani Nikula 77 1.2% Christian König 74 1.2% Andrew Lunn 68 1.1% Jan Kara 60 0.9% Kai Vehmanen 60 0.9% Kees Cook 58 0.9% Florian Fainelli 57 0.9% Linus Walleij 55 0.9%

Once again, Daniel Wheeler heads the list of test credits, having received 15% of all such credits during the 5.16 development cycle. That is over two patches tested per day — every day, weekends and holidays included. Wheeler appears to be doing this work as part of his employer's internal review process, as do many of the other top testers. The top reviewers, instead, tend to be active developers who also manage to get a lot of reviews done. The top two reviewers for 5.16 are the same as for 5.15; Christoph Hellwig managed to review three patches and write two of his own for every day of the 70-day 5.16 development cycle.

A different sort of review is associated with the task of selecting patches to apply and push into the mainline kernel. That decision may involve a thorough review in its own right, or it may rely on the review efforts of others. When maintainers accept patches, they will apply a Signed-off-by tag to those patches. By looking at signoffs by people other than the author of a patch, it is possible to get a picture for who the most active maintainers are. For 5.16 they were:

Top signoffs in 5.16
David S. Miller	1082	7.8%
Greg Kroah-Hartman	1062	7.6%
Mark Brown	558	4.0%
Alex Deucher	472	3.4%
Jens Axboe	442	3.2%
Andrew Morton	400	2.9%
Martin K. Petersen	353	2.5%
Jakub Kicinski	325	2.3%
Mauro Carvalho Chehab	325	2.3%
Bjorn Andersson	305	2.2%
Paolo Bonzini	230	1.7%
Jonathan Cameron	224	1.6%
Kalle Valo	210	1.5%
Arnaldo Carvalho de Melo	203	1.5%
Hans Verkuil	183	1.3%
Felix Fietkau	163	1.2%
David Sterba	162	1.2%
Alexei Starovoitov	154	1.1%
Borislav Petkov	152	1.1%
Saeed Mahameed	148	1.1%

This list of maintainers tends not to change much from one release to another; it is made up of some of the kernel project's most senior developers who have been on the job for many years.

Work on 5.16 was supported by 251 employers that we were able to identify. The most active of those were:

Most active 5.16 employers

By changesets Intel 1454 10.2% (Unknown) 1196 8.4% Google 932 6.6% (None) 781 5.5% Red Hat 765 5.4% AMD 682 4.8% Facebook 641 4.5% Linaro 592 4.2% NVIDIA 463 3.3% Huawei Technologies 422 3.0% SUSE 311 2.2% Oracle 294 2.1% IBM 274 1.9% (Consultant) 266 1.9% Canonical 249 1.8% Arm 244 1.7% Baidu 234 1.6% Renesas Electronics 221 1.6% MediaTek 199 1.4% Code Aurora Forum 192 1.4%

By lines changed Realtek 97237 12.2% Intel 72565 9.1% AMD 67076 8.4% Facebook 50894 6.4% (Unknown) 43152 5.4% (None) 40389 5.0% Linaro 39428 4.9% NVIDIA 38898 4.9% Google 35871 4.5% Red Hat 23312 2.9% Marvell 19136 2.4% MediaTek 15399 1.9% Code Aurora Forum 14564 1.8% Anyfi Networks 13901 1.7% Renesas Electronics 12888 1.6% SUSE 10940 1.4% IBM 10808 1.4% Huawei Technologies 10378 1.3% Cirrus Logic 10046 1.3% Oracle 8728 1.1%

This table, too, tends not to change much from one release to the next. For the curious, the "unknown" category consists of nearly 400 developers, most of whom contributed one or two patches. Any one of these developers is a small contributor to this release, but together they add up to a significant portion of the total patch flow. Many of those developers will move on, having done what they came to the kernel project to do; others are just getting started and will become significant contributors over time.

In summary, 5.16 was just another typical kernel development cycle. Lots of patches from nearly 2,000 developers, all integrated into another solid (though not perfect) kernel release. The kernel project does not lack its share of problems with quality control, testing, support for maintainers, and more, but it nonetheless manages to get the work done on a predictable schedule. Work now begins on 5.17, which will be released in mid-March.

Index entries for this article
Kernel	Releases/5.16

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