Development statistics for the 6.15 Linux kernel

By Jonathan Corbet
May 26, 2025

The 6.14 kernel development cycle only brought in 11,003 non-merge changesets, making it the slowest cycle since 4.0, which was released in 2015. The 6.15 kernel, instead, brought in 14,612 changesets, making it the busiest release since 6.7, released at the beginning of 2024. The kernel development process, in other words, is back up to full speed. The 6.15 release happened on May 25, so the time has come for the obligatory look at where the changes in this release came from.

As a reminder, LWN subscribers can find this information and more, at any time, for any kernel version since 2005, in the LWN Kernel Source Database.

The work in 6.15 was contributed by 2,068 developers — a relatively high number, though it falls short of the record 2,090 seen in the 6.2 development cycle. There were 262 developers who made their first kernel contribution in 6.15. The most active contributors this time around were:

Most active 6.15 developers

By changesets Kent Overstreet 266 1.8% Kuninori Morimoto 191 1.3% Ville Syrjälä 144 1.0% Andy Shevchenko 137 0.9% Alex Deucher 123 0.8% Nam Cao 123 0.8% Sean Christopherson 117 0.8% Krzysztof Kozlowski 115 0.8% Takashi Iwai 114 0.8% Dr. David Alan Gilbert 111 0.8% Thomas Weißschuh 108 0.7% Jani Nikula 106 0.7% Pavel Begunkov 102 0.7% Jakub Kicinski 94 0.6% Eric Biggers 93 0.6% Christoph Hellwig 92 0.6% Arnd Bergmann 91 0.6% Matthew Wilcox 89 0.6% Ian Rogers 89 0.6% Mario Limonciello 87 0.6%

By changed lines Wayne Lin 80287 9.5% Ian Rogers 33886 4.0% Miri Korenblit 29176 3.4% Bitterblue Smith 26801 3.2% Andrew Donnellan 25819 3.0% Edward Cree 12941 1.5% Austin Zheng 12889 1.5% Michael Ellerman 12629 1.5% Dikshita Agarwal 8901 1.1% Nick Chan 8802 1.0% Nick Terrell 8749 1.0% Kent Overstreet 8296 1.0% Christoph Hellwig 7202 0.8% Eric Biggers 7012 0.8% Dr. David Alan Gilbert 6844 0.8% Nuno Das Neves 6419 0.8% Ivaylo Ivanov 5938 0.7% David Howells 5909 0.7% Alex Deucher 5398 0.6% Matthew Brost 5312 0.6%

Once again, the developer with the most changesets was Kent Overstreet, who continues to work on stabilizing the bcachefs filesystem. Kuninori Morimoto contributed a large set of cleanups to the sound subsystem. Ville Syrjälä worked exclusively on the Intel i915 graphics driver. Andy Shevchenko contributed small improvements throughout the driver subsystem, and Alex Deucher worked, as always, on the AMD graphics driver subsystem.

Returning to a pattern often seen in recent years, the "lines changed" column is led by Wayne Lin, who contributed yet another set of AMD GPU header files. Ian Rogers made a number of contributions to the perf subsystem, including updating the large Intel vendor-events files. Miri Korenblit added the new "iwlmld" driver for newer Intel WiFi adapters. Bitterblue Smith added a number of RealTek WiFi driver variants, and Andrew Donnellan removed a couple of unused CXL drivers.

The top testers and reviewers this time around were:

Test and review credits in 6.15

Tested-by Daniel Wheeler 163 9.2% Neil Armstrong 64 3.6% Thomas Falcon 35 2.0% Babu Moger 30 1.7% Shaopeng Tan 30 1.7% Peter Newman 30 1.7% Amit Singh Tomar 30 1.7% Shanker Donthineni 30 1.7% Stefan Schmidt 28 1.6% Nicolin Chen 25 1.4% Xiaochun Lee 25 1.4% Venkat Rao Bagalkote 24 1.4% Andreas Hindborg 21 1.2% Alison Schofield 21 1.2% Carl Worth 21 1.2%	Reviewed-by Simon Horman 271 2.7% Krzysztof Kozlowski 161 1.6% Dmitry Baryshkov 147 1.5% Geert Uytterhoeven 112 1.1% Andrew Lunn 109 1.1% Ilpo Järvinen 105 1.1% Darrick J. Wong 105 1.1% David Sterba 102 1.0% Rob Herring (Arm) 100 1.0% Jonathan Cameron 97 1.0% Linus Walleij 96 1.0% Charles Keepax 93 0.9% Jan Kara 88 0.9% Christoph Hellwig 82 0.8% Jacob Keller 81 0.8%

Daniel Wheeler retains his permanent spot as the top-credited tester; nobody else even comes close. The top reviewers are a bit different this time around, with Simon Horman reviewing just over four networking patches for every day of this development cycle.

There were Tested-by tags in 1,411 6.15 commits (9.7% of the total), while 7,332 (50.2%) of the commits had Reviewed-by tags.

Work on 6.15 was supported by (at least) 195 employers, a slightly smaller number than usual. The most active employers were:

Most active 6.15 employers

By changesets Intel 1755 12.0% (Unknown) 1302 8.9% Google 983 6.7% (None) 930 6.4% Red Hat 889 6.1% AMD 881 6.0% Linaro 645 4.4% SUSE 549 3.8% Meta 493 3.4% NVIDIA 370 2.5% Huawei Technologies 370 2.5% Renesas Electronics 367 2.5% Qualcomm 319 2.2% Arm 301 2.1% Linutronix 296 2.0% Oracle 286 2.0% IBM 282 1.9% Microsoft 259 1.8% (Consultant) 180 1.2% NXP Semiconductors 179 1.2%

By lines changed AMD 125923 14.9% (Unknown) 97908 11.5% Intel 94150 11.1% Google 67461 8.0% IBM 48682 5.7% (None) 45049 5.3% Red Hat 43981 5.2% Qualcomm 34014 4.0% Meta 26182 3.1% Microsoft 19431 2.3% Linaro 16389 1.9% NVIDIA 16191 1.9% SUSE 15175 1.8% Huawei Technologies 14136 1.7% Xilinx 12961 1.5% Collabora 11640 1.4% Arm 9357 1.1% NXP Semiconductors 8857 1.0% Rockchip 8085 1.0% BayLibre 8037 0.9%

This is mostly the usual list of companies that consistently support kernel work from one year to the next. Linutronix has moved up the list this time around, mostly as the result of a lot of work on the kernel's timer subsystem. IBM, once one of the top contributors to the kernel, continues to move downward.

A different view of how the process works can be had by looking at the Signed-off-by tags applied to patches, specifically those applied by developers other than the author. Those additional signoffs are the traces left when developers forward a patch or apply it to a Git repository on its way toward the mainline; they thus give a clue as to who is doing the work of herding patches upstream. For 6.15, the signoff statistics look like this:

Non-author Signed-off-by tags in 6.15

Developers Jakub Kicinski 955 7.0% Mark Brown 774 5.7% Andrew Morton 649 4.8% Alex Deucher 571 4.2% Ingo Molnar 400 2.9% Greg Kroah-Hartman 389 2.9% Jens Axboe 325 2.4% Paolo Abeni 314 2.3% Hans Verkuil 257 1.9% Thomas Gleixner 235 1.7% Christian Brauner 218 1.6% Namhyung Kim 194 1.4% Jonathan Cameron 186 1.4% Alexei Starovoitov 183 1.3% Johannes Berg 160 1.2% Heiko Stuebner 148 1.1% Martin K. Petersen 137 1.0% Vinod Koul 137 1.0% David Sterba 131 1.0% Shawn Guo 130 1.0%

Employers Meta 1702 12.5% Google 1405 10.3% Intel 1310 9.6% Red Hat 1151 8.5% Arm 955 7.0% AMD 908 6.7% Linaro 768 5.7% Microsoft 427 3.1% Linux Foundation 418 3.1% SUSE 404 3.0% (Unknown) 376 2.8% (None) 331 2.4% Qualcomm 307 2.3% NVIDIA 304 2.2% Huawei Technologies 289 2.1% Linutronix 283 2.1% Cisco 281 2.1% Oracle 202 1.5% LG Electronics 194 1.4% IBM 173 1.3%

One patch out of every eight going into the kernel now passes through the hands of a maintainer at Meta, and nearly as many are handled by Google developers.

As of this writing, there are well over 12,000 commits in linux-next, almost all of which can be expected to find their way into the kernel during the 6.16 merge window. That suggests that the next development cycle will be as busy as this one was. As always, keep an eye on LWN to keep up with the next kernel as it is assembled and stabilized.

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