Some 5.14 development statistics

To create 5.14, the kernel community applied 14,735 non-merge changesets from 1,912 developers; 261 of those developers made their first kernel contribution during this cycle. There were 861,000 lines of code added to the kernel and 321,000 lines removed, for a net growth of 540,000 lines.

The most active 5.14 developers were:

Most active 5.14 developers

By changesets Lee Jones 215 1.5% Andy Shevchenko 196 1.3% Mauro Carvalho Chehab 191 1.3% Peng Li 167 1.1% Yang Yingliang 153 1.0% Zhen Lei 145 1.0% Christoph Hellwig 136 0.9% Colin Ian King 136 0.9% Vladimir Oltean 134 0.9% Fabio Aiuto 132 0.9% Takashi Iwai 131 0.9% Sean Christopherson 122 0.8% Jiri Slaby 113 0.8% Jonathan Cameron 108 0.7% Christophe Leroy 107 0.7% Geert Uytterhoeven 102 0.7% Takashi Sakamoto 96 0.7% Krzysztof Kozlowski 94 0.6% Gustavo A. R. Silva 93 0.6% Thomas Gleixner 83 0.6%

By changed lines Aaron Liu 193379 18.9% Aurabindo Jayamohanan Pillai 48184 4.7% Christoph Hellwig 46667 4.6% Mustafa Ismail 32014 3.1% James Smart 30907 3.0% Shiraz Saleem 29185 2.8% Nicholas Kazlauskas 19620 1.9% Kashyap Desai 12891 1.3% Steen Hegelund 12584 1.2% Masahiro Yamada 10517 1.0% Jin Yao 10133 1.0% M Chetan Kumar 8947 0.9% Konrad Dybcio 8853 0.9% Srinivas Kandagatla 8266 0.8% Fabio Aiuto 6976 0.7% Vladimir Oltean 6444 0.6% Thierry Reding 6314 0.6% Takashi Iwai 5858 0.6% Mark Rutland 5612 0.5% Greg Kroah-Hartman 5485 0.5%

Lee Jones seems to have staked out a permanent position as the lead contributor of changesets; he continues to focus on cleanups and warning fixes all over the kernel tree. Andy Shevchenko made a lot of fixes throughout the driver subsystem. Mauro Carvalho Chehab worked mostly in the media subsystem with a bunch of documentation fixes on the side, Peng Li contributed a set of style fixes to various network drivers, and Yang Yingliang fixed a lot of warnings in various drivers.

In the "changed lines" column we see Aaron Liu and Aurabindo Jayamohanan Pillai on top with the inevitable set of amdgpu header files. Christoph Hellwig continues to do extensive refactoring work, mostly in the block subsystem. Mustafa Ismail contributed one patch series adding the Intel Ethernet protocol driver for RDMA, and James Smart added a new SCSI driver.

Work in 5.14 was supported by at least 231 employers, the most active of which where:

Most active 5.14 employers

By changesets Huawei Technologies 1731 11.7% Intel 1331 9.0% (Unknown) 1003 6.8% AMD 879 6.0% Red Hat 854 5.8% Google 756 5.1% (None) 744 5.0% Linaro 654 4.4% SUSE 503 3.4% IBM 445 3.0% NVIDIA 319 2.2% Oracle 290 2.0% Canonical 278 1.9% NXP Semiconductors 276 1.9% Facebook 274 1.9% Arm 255 1.7% (Consultant) 229 1.6% Renesas Electronics 203 1.4% Linux Foundation 170 1.2% Pengutronix 151 1.0%

By lines changed AMD 293439 28.6% Intel 135564 13.2% (Consultant) 50998 5.0% Broadcom 47742 4.7% Linaro 33652 3.3% Red Hat 30978 3.0% Huawei Technologies 29704 2.9% (Unknown) 29631 2.9% Google 29387 2.9% NVIDIA 28415 2.8% (None) 23154 2.3% IBM 22541 2.2% SUSE 19887 1.9% Marvell 17294 1.7% Microchip Technology 14852 1.4% NXP Semiconductors 12200 1.2% Arm 11831 1.2% SoMainline 10599 1.0% Socionext Inc. 10526 1.0% Code Aurora Forum 10050 1.0%

Huawei has found its way to the top of the list of changeset contributors again. Otherwise there is little new or surprising in this list.

Since the beginning, these reports have looked specifically at non-merge changesets, following the reasoning that those are the changes that contain the "real work". Merges, instead, are just the movement of patches from one Git branch or repository to another. That said, merges are a big part of a maintainer's work; each merge requires a look at the code involved and a judgment that the time has come to move that code along to the next stop on its path to the mainline kernel. So perhaps a look at merges, too, makes sense. The most active creators of merge commits in the 5.14 development cycle were:

Merge contributors in 5.14
Linus Torvalds	384	33.8%
David S. Miller	230	20.2%
Olof Johansson	82	7.2%
Mark Brown	54	4.8%
Dave Airlie	52	4.6%
Greg Kroah-Hartman	35	3.1%
Rafael J. Wysocki	28	2.5%
Jakub Kicinski	28	2.5%
Bjorn Helgaas	25	2.2%
Will Deacon	24	2.1%
Arnd Bergmann	16	1.4%
Marc Zyngier	14	1.2%
Stephen Boyd	13	1.1%
Takashi Iwai	10	0.9%
Paolo Bonzini	8	0.7%
Jens Axboe	8	0.7%
Darrick J. Wong	8	0.7%
Thomas Gleixner	6	0.5%
Ingo Molnar	6	0.5%
Jiri Kosina	6	0.5%

Linus Torvalds tends to be notably absent from the statistics in these reports; after all, by his own admission, he does not write much code these days. The merge numbers show where part of his activity is, though; he handles hundreds of pull requests from subsystem maintainers, looks at each one (often more closely than one might expect), and does the merge if it seems like the right thing to do. In the process, he generates one-third of the merges in the kernel history.

There are, however, two ways that any given patch moves through the chain of subsystem maintainers. One is via pull requests, each of which will generate one of the merges seen in the above table. But, before that can happen, a maintainer somewhere must apply the patch to their Git repository to start the process. When that happens, the maintainer will apply a Signed-off-by tag to the patch. To see that aspect of maintainer activity, one needs to look at those tags when applied to patches written by somebody else; the result for 5.14 is:

Non-author signoffs in 5.14
David S. Miller	1625	11.0%
Greg Kroah-Hartman	1118	7.5%
Alex Deucher	867	5.8%
Mark Brown	541	3.6%
Andrew Morton	489	3.3%
Martin K. Petersen	332	2.2%
Paolo Bonzini	324	2.2%
Jens Axboe	324	2.2%
Mauro Carvalho Chehab	284	1.9%
Michael Ellerman	273	1.8%
Takashi Iwai	216	1.5%
Jason Gunthorpe	213	1.4%
Hans Verkuil	209	1.4%
Guangbin Huang	180	1.2%
Will Deacon	176	1.2%
Bjorn Andersson	170	1.1%
Arnaldo Carvalho de Melo	169	1.1%
Jakub Kicinski	154	1.0%
Jonathan Cameron	148	1.0%
Herbert Xu	144	1.0%

Here, we see the maintainers who tend to apply patches directly rather than acting on pull requests; there are some names that appear on both but, in the end, this is a different list. The fact that David Miller appears at the top of both lists just confirms that he gets more done than just about anybody else — it is more than good to seem him apparently running at full capacity again. It also reflects a style of work that involves applying patches to topic branches, then merging them into the local trunk to send upstream; each patch series applied generates a set of non-author signoffs and a merge commit. Other maintainers apply patches directly to upstream-bound branches and do not generate these merges.

Either way, the maintainers who shepherd patches through the system are performing a crucial function within the kernel development process. Without this work, all of those developers cranking out patches would have no place to send them. Maintainership is hard and often unrewarding work; we all owe them some gratitude for keeping this whole development process going.

All told, the kernel development community appears to be continuing to operate smoothly at its usual fast pace. As of this writing, the 5.15 development cycle is already underway with large amounts of work queued to be merged. We will see the above story repeat, with variations of course, over the next nine or ten weeks.