Development statistics for 6.12

Linus Torvalds released the 6.12 kernel on November 17, as expected. This development cycle, the last for 2024, brought 13,344 non-merge changesets into the mainline kernel; that made it a relatively slow cycle from this perspective, but 6.12 includes a long list of significant new features. The time has come to look at where those changes came from, and to look at the year-long LTS cycle as well.

The 6.12 kernel included work from 2,074 developers; this is not a record (that is 2,090 in 6.2), but is close. Of those developers, 335 made their first contribution to the kernel during this cycle; that is a record for the Git era (and probably before as well). The most active developers during this cycle were:

Most active 6.12 developers

By changesets Krzysztof Kozlowski 225 1.7% Kent Overstreet 186 1.4% Tejun Heo 131 1.0% Jinjie Ruan 123 0.9% Javier Carrasco 109 0.8% Sean Christopherson 108 0.8% Andy Shevchenko 107 0.8% Takashi Iwai 106 0.8% Alex Deucher 95 0.7% Nuno Sa 94 0.7% Christoph Hellwig 90 0.7% Frank Li 89 0.7% Jani Nikula 88 0.7% Rob Herring 85 0.6% Matthew Wilcox 85 0.6% Ian Rogers 83 0.6% Namhyung Kim 75 0.6% Christian Brauner 74 0.6% Christophe JAILLET 73 0.5% Hongbo Li 72 0.5%

By changed lines Cezary Rojewski 22850 3.7% Yevgeny Kliteynik 17704 2.8% Samson Tam 14305 2.3% Tejun Heo 14224 2.3% Herbert Xu 11867 1.9% Nikita Shubin 9270 1.5% Pavitrakumar M 8378 1.3% Philipp Hortmann 7690 1.2% Eddie James 7138 1.1% Lorenzo Stoakes 6919 1.1% Dmitry Torokhov 6667 1.1% Alexandre Mergnat 6385 1.0% Kent Overstreet 6309 1.0% David Howells 5435 0.9% Harald Freudenberger 5124 0.8% Takashi Iwai 4922 0.8% Deven Bowers 4873 0.8% Inochi Amaoto 4739 0.8% Junfeng Guo 4503 0.7% Chuck Lever 4416 0.7%

Krzysztof Kozlowski continued a long-running effort to refactor low-level device code and devicetree bindings. Kent Overstreet is also working on a long-running project — the effort to stabilize the bcachefs filesystem. Tejun Heo contributed the extended scheduler class. Jinjie Ruan and Javier Carrasco both contributed a lot of cleanups in the driver subsystem.

In the "lines changed" column, Cezary Rojewski removed a number of old audio drivers. Yevgeny Kliteynik added a bunch of functionality to the mlx5 network-interface driver. Samson Tam added some new features to the AMD graphics driver, and Herbert Xu reverted a set of cryptographic-driver patches that were not properly submitted.

There were Reviewed-by tags in 48% of the commits merged for 6.12, while just under 10% of the commits in this release included Tested-by tags. The top testers and reviewers this time around were:

Test and review credits in 6.12
Tested-by Daniel Wheeler 198 14.6% Philipp Hortmann 58 4.3% Arnaldo Carvalho de Melo 55 4.0% Rafal Romanowski 33 2.4% Alexander Sverdlin 30 2.2% Jonathan Cameron 25 1.8% Valentin Schneider 23 1.7% Ojaswin Mujoo 22 1.6% Alibek Omarov 20 1.5% Zi Yan 19 1.4% Pucha Himasekhar Reddy 18 1.3% Andreas Kemnade 18 1.3% Alice Ryhl 17 1.3% Björn Töpel 17 1.3%	Reviewed-by Simon Horman 210 2.5% Krzysztof Kozlowski 180 2.2% Andrew Lunn 131 1.6% David Sterba 116 1.4% Jan Kara 109 1.3% Darrick J. Wong 99 1.2% Christoph Hellwig 98 1.2% Jeff Layton 97 1.2% Josef Bacik 95 1.1% Geert Uytterhoeven 93 1.1% Jonathan Cameron 90 1.1% Rob Herring 87 1.0% Andy Shevchenko 82 1.0% Konrad Dybcio 81 1.0%

The testing side is dominated, as usual, by people who seem to do that work as their primary job; one exception would be Arnaldo Carvalho de Melo, who tests a lot of perf patches as the maintainer before applying them. Simon Horman was the most prolific reviewer this time around, adding his tag to over three network-subsystem patches every day of this development cycle.

Work on 6.12 was supported by 218 employers that we were able to identify — a typical number. The most active employers were:

Most active 6.12 employers
By changesets Intel 1240 9.3% (Unknown) 1173 8.8% Google 957 7.2% AMD 810 6.1% Huawei Technologies 791 5.9% (None) 672 5.0% Red Hat 651 4.9% Linaro 618 4.6% Meta 480 3.6% NVIDIA 382 2.9% SUSE 361 2.7% Oracle 262 2.0% Renesas Electronics 254 1.9% IBM 249 1.9% Arm 241 1.8% NXP Semiconductors 236 1.8% (Consultant) 229 1.7% Qualcomm 175 1.3% Microsoft 159 1.2% Linutronix 140 1.0%	By lines changed Intel 68687 11.0% (Unknown) 52196 8.3% AMD 44794 7.2% Google 42921 6.9% Red Hat 38609 6.2% Meta 30757 4.9% NVIDIA 30555 4.9% IBM 20294 3.2% Oracle 18201 2.9% Linaro 17513 2.8% (None) 17146 2.7% SUSE 15243 2.4% BayLibre 14470 2.3% Qualcomm 11740 1.9% NXP Semiconductors 11214 1.8% Microsoft 10858 1.7% Huawei Technologies 10181 1.6% Realtek 9941 1.6% YADRO 9274 1.5% Arm 8545 1.4%

This list seldom contains surprises, and 6.12 follows in the usual pattern. One notable point is the appearance of Linutronix; that is a result of the merging of the final realtime patches and a fair amount of related refactoring work.

The longer cycle

While the kernel development cycle takes nine or ten weeks, almost without exception, it is a rare user who installs all of those releases. Instead, an increasing portion of the user body is running one of the long-term-support (LTS) releases and the stable updates that are built on top of them. By convention, the final release of the year becomes an LTS release.

As a result, there is an argument to be made that the real kernel development cycle takes about one year — the time that elapses between the LTS releases that are actually deployed by users. The 6.12 release, being the last release of 2024, is thus the end of that longer cycle, so there may be value in looking at the statistics for the full year.

Since the release of the last LTS kernel (6.6), the development community has created six releases, incorporating 86,715 non-merge changesets from 5,111 developers. The most active developers over the whole year were:

Most active 6.7-12 developers

By changesets Kent Overstreet 3972 4.6% Uwe Kleine-König 1596 1.8% Krzysztof Kozlowski 1339 1.5% Andy Shevchenko 817 0.9% Jani Nikula 676 0.8% Dmitry Baryshkov 637 0.7% Christoph Hellwig 634 0.7% Ville Syrjälä 581 0.7% Johannes Berg 568 0.7% Matthew Wilcox 537 0.6% Eric Dumazet 489 0.6% Ian Rogers 474 0.5% Geert Uytterhoeven 471 0.5% Darrick J. Wong 446 0.5% Thomas Zimmermann 431 0.5% Kees Cook 401 0.5% Arnd Bergmann 395 0.5% Sean Christopherson 381 0.4% Jeff Johnson 378 0.4% Jakub Kicinski 374 0.4%

By changed lines Kent Overstreet 259293 5.1% Aurabindo Pillai 228673 4.5% Hawking Zhang 152950 3.0% Ian Rogers 133772 2.6% Qingqing Zhuo 101474 2.0% Dmitry Baryshkov 88968 1.7% Hamza Mahfooz 73053 1.4% Arnd Bergmann 71392 1.4% Ard Biesheuvel 70780 1.4% Ben Li 68066 1.3% Lang Yu 66939 1.3% Philipp Hortmann 63036 1.2% Matthew Sakai 58728 1.2% Darrick J. Wong 55467 1.1% Matthew Brost 51447 1.0% Jakub Kicinski 47447 0.9% Matthew Wilcox 40377 0.8% Neil Armstrong 36116 0.7% Sarah Walker 29771 0.6% David Howells 27675 0.5%

Unsurprisingly, these results are consistent with what has been seen over the course of the last year. Overstreet, it should be noted, found his way to the top of both lists through the merger of a body of work that was developed out-of-tree for years. The main source of new lines of code coming into the kernel, though, was the seemingly endless stream of machine-generated header files for the amdgpu driver.

The top testers and reviewers over the longer cycle were:

Test and review credits in 6.7-12

Tested-by Daniel Wheeler 1136 14.1% Philipp Hortmann 244 3.0% Pucha Himasekhar Reddy 214 2.7% Arnaldo Carvalho de Melo 124 1.5% Michael Kelley 101 1.3% Neil Armstrong 99 1.2% Sohil Mehta 92 1.1% Rafal Romanowski 85 1.1% Nicolin Chen 81 1.0% Randy Dunlap 64 0.8% Björn Töpel 57 0.7% Babu Moger 56 0.7% Geert Uytterhoeven 54 0.7% Sujai Buvaneswaran 54 0.7% Guenter Roeck 51 0.6% Kees Cook 50 0.6% Helge Deller 50 0.6% Johan Hovold 49 0.6% Nathan Chancellor 47 0.6% Shameer Kolothum 44 0.5%

Reviewed-by Simon Horman 1146 2.1% Christoph Hellwig 1009 1.9% Krzysztof Kozlowski 1002 1.9% Konrad Dybcio 826 1.5% Dmitry Baryshkov 697 1.3% AngeloGioacchino Del Regno 657 1.2% David Sterba 626 1.2% Andy Shevchenko 611 1.1% Rodrigo Vivi 574 1.1% Ilpo Järvinen 550 1.0% Andrew Lunn 536 1.0% Rob Herring 534 1.0% Geert Uytterhoeven 525 1.0% Kees Cook 465 0.9% Matt Roper 451 0.8% Linus Walleij 437 0.8% Jani Nikula 430 0.8% Darrick J. Wong 426 0.8% Jeff Layton 424 0.8% Hawking Zhang 418 0.8%

The most active employers (out of the 361 total) over the longer cycle were:

Most active 6.7-12 employers

By changesets Intel 11356 13.1% (None) 6881 7.9% Google 5920 6.8% (Unknown) 5668 6.5% AMD 5233 6.0% Linaro 5112 5.9% Red Hat 4863 5.6% Huawei Technologies 2459 2.8% SUSE 2319 2.7% Meta 2207 2.5% Oracle 1986 2.3% Pengutronix 1871 2.2% Qualcomm 1792 2.1% NVIDIA 1713 2.0% IBM 1612 1.9% Renesas Electronics 1574 1.8% (Consultant) 1227 1.4% Arm 1178 1.4% NXP Semiconductors 916 1.1% Texas Instruments 781 0.9%

By lines changed AMD 918483 18.1% Intel 540531 10.6% Google 378278 7.4% (None) 352401 6.9% Linaro 314793 6.2% Red Hat 308732 6.1% (Unknown) 292949 5.8% Meta 150897 3.0% Oracle 136086 2.7% Qualcomm 108629 2.1% NVIDIA 94799 1.9% SUSE 86590 1.7% Realtek 78260 1.5% Emerson 63036 1.2% IBM 61320 1.2% Collabora 58147 1.1% Renesas Electronics 56839 1.1% Huawei Technologies 50113 1.0% NXP Semiconductors 41451 0.8% Microsoft 38985 0.8%

Intel has cemented its position as the most prolific contributor of changesets over this year, with nearly double the number of the next company (Google) on the list. Otherwise, though, this list looks similar to the 6.6 version at the end of the last long cycle.

All told, the kernel's development process continues to incorporate changes and bring in new developers at a high rate (though that rate has been stable for the last few years). As of this writing, there are over 10,000 changes in linux-next waiting for the 6.13 merge window to open, so there is plenty of work to start the next development cycle (and the next year-long LTS cycle). As always, LWN will be there to tell you how it goes.

Index entries for this article
Kernel	Releases/6.12

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