Development statistics for the 5.0 kernel

As of this writing, 12,517 non-merge changesets have been pulled into the mainline repository for the 5.0 release. This is low compared to the kernels that came before:

Cycle	Changesets
4.15	14,866
4.16	13,630
4.17	13,541
4.18	13,283
4.19	14,043
4.20	13,884
5.0	12,517	(so far)

One has to go back to 4.7, released in July 2016, to find a development cycle that brought in fewer changesets than 5.0. The number of developers contributing to 5.0 was 1,712, roughly equivalent to previous cycles; 276 of those developers made their first kernel contribution in this development cycle.

The most active developers were:

Most active 5.0 developers

By changesets Christoph Hellwig 213 1.7% Masahiro Yamada 135 1.1% Colin Ian King 135 1.1% Jens Axboe 112 0.9% Arnaldo Carvalho de Melo 112 0.9% Yangtao Li 106 0.8% Yue Haibing 100 0.8% Kuninori Morimoto 95 0.8% Andy Shevchenko 94 0.8% Rob Herring 92 0.7% Maxime Ripard 91 0.7% Boris Brezillon 89 0.7% Jakub Kicinski 83 0.7% Michael Straube 83 0.7% Thierry Reding 82 0.7% Ville Syrjälä 82 0.7% Geert Uytterhoeven 80 0.6% Linus Walleij 80 0.6% Paul E. McKenney 78 0.6% Gustavo A. R. Silva 77 0.6%

By changed lines Olof Johansson 41834 6.0% Kan Liang 31458 4.5% Yong Zhi 22799 3.3% Aaro Koskinen 20462 3.0% Firoz Khan 15981 2.3% Jens Axboe 13009 1.9% Tony Lindgren 12237 1.8% Boris Brezillon 11422 1.7% Sean Christopherson 10614 1.5% Dong Aisheng 7998 1.2% Eric Biggers 7476 1.1% Manivannan Sadhasivam 6724 1.0% Christoph Hellwig 6199 0.9% Federico Vaga 5877 0.8% Jordan Crouse 5772 0.8% Kuninori Morimoto 5255 0.8% Florian Westphal 5120 0.7% Mauro Carvalho Chehab 5097 0.7% Lorenzo Bianconi 4941 0.7% Sagi Grimberg 4827 0.7%

Christoph Hellwig was the most prolific contributor of changesets this time around; he did a lot of work in the block subsystem and the DMA API. Masahiro Yamada's work was mostly focused on improvements to the kernel's build system, Colin Ian King continues to make spelling and coding-style fixes throughout the tree, Jens Axboe converted a lot of block drivers to the multiqueue API (along with many other block-layer changes), and Arnaldo Carvalho de Melo worked extensively on the perf utility. Of the top twenty developers with regard to changesets, only one got there through work on the staging tree — a significant change from years past.

Switching to the "lines changed" column: Olof Johansson only contributed seven changesets to 5.0, but one of them was removing the old and unmaintained eicon ISDN driver. Other top contributors in the "lines changed" column include Kan Liang for adding some JSON metrics to the perf utility, Yong Zhi for the Intel IPU3 driver, Aaro Koskinen for work on MIPS OCTEON support, and Firoz Khan, who reworked how the system-call tables are generated for most architectures.

A total of 226 employers supported work on 5.0, which is a typical number. The most active of those were:

Most active 5.0 employers

By changesets Intel 1360 10.9% (None) 937 7.5% (Unknown) 867 6.9% Red Hat 859 6.9% Linaro 552 4.4% Google 487 3.9% Mellanox 481 3.8% SUSE 418 3.3% AMD 415 3.3% Renesas Electronics 394 3.1% IBM 347 2.8% Huawei Technologies 320 2.6% (Consultant) 311 2.5% Facebook 268 2.1% Bootlin 261 2.1% NXP Semiconductors 247 2.0% ARM 226 1.8% Oracle 204 1.6% Canonical 171 1.4% Code Aurora Forum 148 1.2%

By lines changed Intel 116158 16.8% Facebook 66816 9.7% Linaro 40368 5.8% Red Hat 33041 4.8% (None) 32191 4.7% (Unknown) 26858 3.9% Mellanox 26487 3.8% Google 24099 3.5% Nokia 20600 3.0% Bootlin 19019 2.7% AMD 17137 2.5% NXP Semiconductors 16716 2.4% SUSE 14546 2.1% Renesas Electronics 14103 2.0% IBM 13068 1.9% Atomide 12237 1.8% Huawei Technologies 10952 1.6% Code Aurora Forum 10566 1.5% (Consultant) 9353 1.4% ARM 7034 1.0%

The kernel development community relies heavily on its testers and reviewers. The testing and review picture for 5.0 looks like this:

Test and review credits in 5.0

Tested-by Andrew Bowers 50 6.4% Ming Lei 37 4.7% Jarkko Sakkinen 20 2.6% Arnaldo Carvalho de Melo 18 2.3% Janusz Krzysztofik 17 2.2% Alan Tull 17 2.2% Tony Luck 16 2.1% Aaron Brown 15 1.9% Jesper Dangaard Brouer 15 1.9% Heiko Stuebner 14 1.8% Marek Szyprowski 13 1.7% Corentin Labbe 13 1.7% Adam Ford 12 1.5% Wolfram Sang 11 1.4% Tom Zanussi 11 1.4% Steve Longerbeam 11 1.4% Ravulapati Vishnu vardhan Rao 11 1.4% David Ahern 10 1.3% Jarkko Nikula 10 1.3% Ondrej Jirman 10 1.3%

Reviewed-by Rob Herring 186 3.8% Ville Syrjälä 125 2.5% Simon Horman 108 2.2% Geert Uytterhoeven 92 1.9% Hannes Reinecke 90 1.8% Christoph Hellwig 83 1.7% Alex Deucher 72 1.5% David Sterba 69 1.4% Andrew Morton 60 1.2% Omar Sandoval 60 1.2% John Hurley 58 1.2% Rodrigo Vivi 57 1.2% Chris Wilson 57 1.2% Sagi Grimberg 56 1.1% Petr Machata 56 1.1% Daniel Vetter 52 1.1% Christian König 51 1.0% Chao Yu 48 1.0% Andy Shevchenko 44 0.9% Nikolay Borisov 41 0.8%

The kernel's repository can tell us who the patches came from, but it is silent on the question of where they came from. Some insights, though, can be had by looking at the time zone stored in the commit time for each patch. For 5.0, the result looks like this:

Originating time zone for 5.0 patches
Offset	Changesets		Notes
-8:00	1,676		US west coast
-7:00	622		US mountain
-6:00	361		US central
-5:00	939		US east coast
-4:00	295
-3:00	158		Brazil
-2:00	105
0:00	1,611		UK
+1:00	2,812		Western Europe
+2:00	1,457		Eastern Europe
+3:00	447		Finland, Russia
+5:30	513		India
+8:00	952		China
+9:00	302		Japan, Korea
+10:00	99		Australia
+11:00	140		Australia

A few time zones with less than ten changesets have been omitted from the above table. The association of time zones with countries is, of course, approximate. Daylight savings time can throw things off, as can developers whose systems are not set to their local time. If nothing else, the number of patches with times in UTC is probably higher than the number that actually came from countries in that time zone. There are still a few conclusions that can be drawn, though: it seems clear that an awful lot of kernel work still happens at or just east of the Prime Meridian, for example.

More than anything else, though, this table highlights something we already knew: the Linux kernel community is truly global in scope. Patches come in at a high rate from all over the world and are integrated in a (usually) smooth manner. In this sense, the 5.0 kernel is just like the many that came before it; it's business as usual in the kernel community.