Statistics from the 5.10 kernel development cycle

Linus Torvalds released the 5.10 kernel on December 13 at the end of a typical nine-week development cycle. At that point, 16,174 non-merge changesets had been pulled into the mainline; that makes 5.10 a larger cycle than 5.9, but it falls just short of the record set by 5.8, which ended with 16,308 changesets. For the most part 5.10 is just another routine kernel release, but there are a couple of interesting things to be seen in the overall statistics.

A total of 1,971 developers contributed to 5.10 — again, just short of the record set by 5.8. Of those developers, 252 (just under 13%) made their first contribution in 5.10; that is the lowest number seen since 5.6. The most active 5.10 developers were:

Most active 5.10 developers

By changesets Krzysztof Kozlowski 491 3.0% Mauro Carvalho Chehab 378 2.3% Christoph Hellwig 265 1.6% Pierre-Louis Bossart 116 0.7% Lee Jones 116 0.7% Randy Dunlap 115 0.7% Allen Pais 112 0.7% Jonathan Cameron 107 0.7% Maxime Ripard 103 0.6% Dave Airlie 98 0.6% Lad Prabhakar 97 0.6% Andy Shevchenko 87 0.5% Chris Wilson 85 0.5% Evan Quan 84 0.5% Colin Ian King 84 0.5% Andrii Nakryiko 82 0.5% Vladimir Oltean 80 0.5% Alex Deucher 79 0.5% Qinglang Miao 77 0.5% Kees Cook 70 0.4%

By changed lines Sudeep Dutt 26779 3.5% Mauro Carvalho Chehab 22741 2.9% Corentin Labbe 19091 2.5% Fabio Estevam 16757 2.2% Christoph Hellwig 14286 1.9% Cezary Rojewski 14106 1.8% Chandan Uddaraju 9357 1.2% Daniel W. S. Almeida 8012 1.0% Mike Travis 7873 1.0% Andrii Nakryiko 7455 1.0% Oded Gabbay 6989 0.9% Hans Verkuil 6839 0.9% Larry Finger 6758 0.9% Vadym Kochan 6382 0.8% Krzysztof Kozlowski 6371 0.8% Mauro Rossi 6227 0.8% Jonathan Marek 6106 0.8% Marc Kleine-Budde 6049 0.8% Jin Yao 5811 0.8% Jiaxin Yu 5464 0.7%

The author contributing the most changesets to 5.10 was Krzysztof Kozlowski, who made cleanups and small improvements all over the Arm and driver subsystems — at a rate of almost eight per day, seven days per week. Mauro Carvalho Chehab did a lot of work across the media, documentation, and staging subsystems. Christoph Hellwig's work included significant rewrites across the filesystem and block layers, along with the set_fs() removal. Pierre-Louis Bossart did a lot of work in the sound subsystem, and Lee Jones contributed a large number of warning fixes.

Sudeep Dutt contributed a single patch to 5.10, but that patch removed the drivers for Intel "many integrated core" (MIC) devices, deleting enough code to land at the top of the "lines changed" column. Corentin Labbe resurrected the Zoran MJPEG capture driver in the staging tree, and Fabio Estevam removed a bunch of old Arm board files.

The busiest testers and bug reporters this time were:

Test and report credits in 5.10
Tested-by Hoegeun Kwon 86 7.3% Chanwoo Choi 79 6.7% Stefan Wahren 79 6.7% Thierry Reding 33 2.8% Aaron Brown 31 2.6% Arnaldo Carvalho de Melo 24 2.0% Nikolay Borisov 23 1.9% Nick Desaulniers 21 1.8% Yoshihiro Shimoda 16 1.4% Jonas Karlman 16 1.4% Douglas Gilbert 16 1.4% Marek Szyprowski 15 1.3% Srinivas Kandagatla 13 1.1% Sedat Dilek 13 1.1% Daniel Thompson 12 1.0%	Reported-by kernel test robot 191 15.1% Hulk Robot 190 15.0% Syzbot 97 7.7% Dan Carpenter 40 3.2% Stephen Rothwell 23 1.8% Randy Dunlap 20 1.6% Qian Cai 17 1.3% Naresh Kamboju 14 1.1% Julien Grall 8 0.6% Alexei Starovoitov 7 0.6% Rob Herring 7 0.6% Marek Szyprowski 7 0.6% Colin Ian King 7 0.6% Geert Uytterhoeven 6 0.5% Lars-Peter Clausen 6 0.5%

The top three testers show an interesting pattern: their Tested-by tags all appear together on the same patches, all targeting the vc4 DRM driver. On the report side, we see that nearly 38% of all credited bug reports come from automated testing systems. Note that, since these tags appear in patches, they indicate reports that actually resulted in some sort of fix; that is a lot of bugs that won't be around to affect users later on.

A total of 228 companies (that we know of) supported work on the 5.10 kernel, an increase relative to recent past releases. The companies supporting the most work were:

Most active 5.10 employers

By changesets Huawei Technologies 1434 8.9% Intel 1297 8.0% (Unknown) 1075 6.6% (None) 954 5.9% Red Hat 915 5.7% Google 848 5.2% AMD 698 4.3% Linaro 670 4.1% Samsung 570 3.5% IBM 521 3.2% NXP Semiconductors 439 2.7% Facebook 422 2.6% Oracle 414 2.6% SUSE 410 2.5% (Consultant) 404 2.5% Code Aurora Forum 313 1.9% Arm 307 1.9% Renesas Electronics 283 1.7% NVIDIA 262 1.6% Texas Instruments 218 1.3%

By lines changed Intel 96976 12.6% Huawei Technologies 41049 5.3% (Unknown) 40948 5.3% Google 39160 5.1% NXP Semiconductors 35898 4.7% (None) 30998 4.0% Red Hat 30467 3.9% Code Aurora Forum 29615 3.8% Linaro 29384 3.8% Facebook 27479 3.6% BayLibre 24159 3.1% AMD 23343 3.0% (Consultant) 19905 2.6% IBM 18312 2.4% MediaTek 15893 2.1% Arm 13390 1.7% Texas Instruments 11814 1.5% SUSE 11063 1.4% Oracle 10542 1.4% NVIDIA 10481 1.4%

The presence of Huawei at the top of the "by changesets" column may be a bit of a surprise, though something similar happened in 5.8. As was the case then, Chehab's work obviously helped to drive that number, but it was also the result of 94 other developers working for Huawei who contributed at least one patch to 5.10. Huawei has built up a significant kernel-development operation. Beyond that, these results are mostly as one would expect.

Another difference in this cycle can be seen by looking at the non-author signoffs in the merged commits. Applying a Signed-off-by tag to a patch that one did not write is usually done by maintainers who are applying patches to be sent upstream; looking at these signoffs thus give an indication of who the gatekeepers to the kernel are. For 5.10, the results look like this:

Non-author signoffs in 5.10

Developers David S. Miller 1074 7.0% Greg Kroah-Hartman 780 5.1% Mark Brown 707 4.6% Alex Deucher 609 4.0% Jakub Kicinski 486 3.2% Mauro Carvalho Chehab 485 3.1% Kalle Valo 453 2.9% Andrew Morton 423 2.7% Jens Axboe 329 2.1% Alexei Starovoitov 317 2.1% Hans Verkuil 315 2.0% Martin K. Petersen 289 1.9% Michael Ellerman 245 1.6% Vinod Koul 239 1.6% Shawn Guo 197 1.3% Paolo Bonzini 196 1.3% Borislav Petkov 187 1.2% David Sterba 176 1.1% Herbert Xu 175 1.1% Will Deacon 172 1.1%

Employers Red Hat 2198 14.3% Linaro 1588 10.3% Facebook 1214 7.9% Intel 1143 7.4% Google 1082 7.0% Linux Foundation 863 5.6% Huawei Technologies 788 5.1% SUSE 710 4.6% AMD 642 4.2% Code Aurora Forum 508 3.3% IBM 418 2.7% Oracle 407 2.6% (None) 392 2.5% NVIDIA 364 2.4% Cisco 315 2.0% Arm 296 1.9% Qualcomm 239 1.6% (Consultant) 221 1.4% Texas Instruments 187 1.2% Samsung 138 0.9%

Seeing David Miller, the maintainer of the networking subsystem, at the top of this list is traditional, and he occupies this position for 5.10 as well. Miller, unfortunately, abruptly dropped out of the kernel community just after the 5.9 release due to a health issue, so this table reflects his work done prior to the 5.10 merge window. After that, Jakub Kicinski took over networking maintenance, which explains his appearance on the list (and Facebook's relatively high position). This change will be more strongly felt in the 5.11 release; Kicinski currently has signed off nearly 900 patches in linux-next.

Happily, Miller is recovering and has started applying networking patches again. Meanwhile, this episode turned into an unplanned test of the community's response when one of its most active maintainers is no longer able to do that work. That response appears to have gone well, with the flow of networking patches into the mainline and linux-next continuing at a strong pace. There appears to have been little disruption in the networking community overall.

It would be nice to believe that all important kernel subsystems are as well prepared for an abrupt maintainer change, but that is almost certainly not the case. So the kernel community might not pass the next test in such good form. That said, the numbers this time around show that kernel development is still going strong; kernels are released on a predictable schedule, participation across the community is high, and there are still numerous new developers making their debut in each release. 2020 was a difficult year, but the kernel community has gotten through it with, it seems, relatively little trouble.

Index entries for this article
Kernel	Releases/5.10

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