Development statistics for the 7.1 kernel

This release saw the merging of 15,849 non-merge changesets from 2,479 developers. That makes 7.1 one of the busiest development cycles in the kernel's history; only four other releases brought in more commits. The 6.7 release remains the busiest ever, with 17,284 commits; the size of that release was driven by the ill-fated addition of the bcachefs filesystem and all of its development history. The 5.8, 5.10, and 5.13 also brought in more commits than 7.1, though by much smaller margins.

The number of developers working on 7.1 does set a new record, beating the short-lived record of 2,362 set by 7.0. The trend here merits some attention, but we'll start with the usual numbers. The most prolific developers working on 7.1 were:

Most active 7.1 developers

By changesets Johan Hovold 181 1.1% Thomas Weißschuh 175 1.1% Eric Biggers 168 1.1% Stefan Metzmacher 155 1.0% Krzysztof Kozlowski 148 0.9% Rafael J. Wysocki 147 0.9% Russell King 130 0.8% Tejun Heo 125 0.8% Christoph Hellwig 122 0.8% Eric Dumazet 120 0.8% Jakub Kicinski 119 0.8% Sean Christopherson 113 0.7% Thorsten Blum 101 0.6% Thomas Zimmermann 86 0.5% Dmitry Torokhov 85 0.5% Andy Shevchenko 84 0.5% Mauro Carvalho Chehab 84 0.5% Chuck Lever 79 0.5% Bartosz Golaszewski 77 0.5% Lorenzo Stoakes 77 0.5%

By changed lines Jakub Kicinski 126367 12.7% Roman Li 105777 10.7% Namjae Jeon 54445 5.5% Andrew Lunn 16180 1.6% Eric Biggers 14471 1.5% Stefan Metzmacher 14403 1.5% Taniya Das 11956 1.2% Alexei Starovoitov 11410 1.2% Andy Shevchenko 7673 0.8% Mauro Carvalho Chehab 7637 0.8% Christian Brauner 7483 0.8% Pankaj Patil 7181 0.7% Christoph Hellwig 6368 0.6% Krzysztof Kozlowski 5993 0.6% Besar Wicaksono 5873 0.6% Dmitry Baryshkov 5787 0.6% Tejun Heo 5698 0.6% Derek J. Clark 5288 0.5% Vincent Donnefort 5033 0.5% Ratheesh Kannoth 4992 0.5%

In the lines-changed column, Jakub Kicinski [KSDB] removed a large chunk of old and unmaintained networking code, including the ISDN, Bluetooth CMTP, and ATM subsystems. Roman Li [KSDB] added yet another big set of amdgpu header files. Namjae Jeon [KSDB] has brought back the older NTFS filesystem implementation and added a lot of new features to it. Andrew Lunn [KSDB] removed a set of unmaintained networking drivers.

Nearly 8% of the commits in 7.1 carried Tested-by tags, while almost 51% had Reviewed-by tags. Both of those numbers are relatively low compared to recent releases. The top testers and reviewers this time were:

Test and review credits in 7.1
Tested-by Daniel Wheeler 89 5.8% Fuad Tabba 61 3.9% Gavin Shan 40 2.6% Shaopeng Tan 40 2.6% Mohd Ayaan Anwar 40 2.6% Jesse Chick 40 2.6% Mostafa Saleh 36 2.3% Punit Agrawal 34 2.2% Jon Hunter 33 2.1% Zeng Heng 31 2.0% Lad Prabhakar 29 1.9% Peter Newman 28 1.8% Eric Biggers 27 1.7% Venkat Rao Bagalkote 22 1.4% Randy Dunlap 21 1.4%	Reviewed-by Konrad Dybcio 334 3.1% Dmitry Baryshkov 300 2.8% Andy Shevchenko 197 1.9% Krzysztof Kozlowski 181 1.7% Christian König 170 1.6% Ilpo Järvinen 161 1.5% Simon Horman 140 1.3% Frank Li 134 1.3% Geert Uytterhoeven 122 1.1% Christoph Hellwig 119 1.1% Jonathan Cameron 118 1.1% Gary Guo 114 1.1% Andrea Righi 103 1.0% Rob Herring 100 0.9% Lorenzo Stoakes 94 0.9%

Daniel Wheeler [KSDB] maintains his perpetual position as the kernel's top credited tester. On the review side, Konrad Dybcio [KSDB] added his tag to 334 changes while Dmitry Baryshkov [KSDB] tagged 300; both performed reviews almost exclusively for Qualcomm drivers and devicetree files, mostly written by their Qualcomm colleagues.

Development for the 7.1 release was supported by 230 employers that we were able to identify; the most active of those were:

Most active 7.1 employers

By changesets (Unknown) 2160 13.6% Intel 1435 9.1% Google 1227 7.7% AMD 828 5.2% Qualcomm 787 5.0% Red Hat 745 4.7% (None) 694 4.4% NVIDIA 595 3.8% Meta 535 3.4% (Consultant) 500 3.2% SUSE 459 2.9% Oracle 390 2.5% Arm 334 2.1% Renesas Electronics 289 1.8% NXP Semiconductors 254 1.6% IBM 215 1.4% Huawei Technologies 210 1.3% Kylin 181 1.1% Linutronix 171 1.1% SerNet 155 1.0%

By lines changed Meta 156583 15.8% AMD 136736 13.8% (Unknown) 76738 7.7% Qualcomm 75847 7.6% Samsung 55391 5.6% Google 54537 5.5% Intel 48917 4.9% NVIDIA 37374 3.8% Red Hat 35706 3.6% (None) 35178 3.5% Oracle 15837 1.6% SerNet 14403 1.5% Arm 13030 1.3% SUSE 12208 1.2% NXP Semiconductors 11777 1.2% Huawei Technologies 11580 1.2% Realtek 10314 1.0% (Consultant) 9984 1.0% Marvell 8282 0.8% Amutable 7483 0.8%

As usual, there is little change here from previous development cycles.

The developers keep coming

There is one thing that is clearly changing, though. The 7.0 development-statistics article noted that the number of first-time kernel contributors has been growing. The 7.1 cycle continued that trend with 530 new contributors [KSDB], far more than the previous record of 489 set by 7.0. The numbers now look like this:

This trend, which shows no signs of stopping, is almost certainly driven by the increasing availability of LLM-based development tools; it has made itself felt in a number of ways. There are 299 commits in 7.1 that include an Assisted-by tag indicating the use of such a tool. The number of actual commits created with LLM involvement must be significantly higher, though; a number of developers are clearly not complying with the kernel's rules for disclosing that use.

These new developers are showing up in surprising places. The serial-line IP (SLIP) protocol implementation, for example, has seen almost no attention outside of maintenance changes for years, but it is now seeing fixes like this one from Weiming Shi [KSDB], a developer who first showed up in 6.19. The long-unloved floppy driver received this fix (since reverted) from 6.17 first-timer Guangshuo Li [KSDB]. The OMFS filesystem received its first non-mechanical change in many years from first-timer HyungJung Joo [KSDB].

The most prolific 7.1 first-timer, Michael Bommarito [KSDB] with 60 commits, contributed fixes to the SMB filesystem, the SCTP network protocol, the Bluetooth subsystem, io_uring, the SCSI subsystem, the amdgpu driver, the RDMA RoCEv2 implementation, and beyond. Almost all of those patches carried Assisted-by tags. There are few kernel developers who could make substantial changes across that much of the kernel; the ability of a previously unseen developer to do that is something new. Whether any developer, new or old, can fully understand substantive patches to that range of kernel subsystems is a different question.

Then, there is the seemingly infinite stream of typo fixes that has turned into an outright flood in recent times. As the documentation maintainer, I welcome these changes as a way for a new developer to become familiar with the development process, but I also try to encourage developers to move on to more substantial changes — advice that is taken less often than I would like.

Of course, access to an LLM is not the only reason a developer might enter our community. A minimum of 132 of the first-time developers seen in this development cycle can already be associated with an employer. Qualcomm leads the pack with 15 first-time developers; AMD employed 14, and Google 12. In total, 51 companies employed first-time 7.1 developers.

One of the many motivations behind bringing Rust into the kernel was the hope of attracting younger developers into the community. A total of five of the new developers (just under 1%) touched Rust files (those whose names end in ".rs"). Three of those developers contributed single, small patches, one added a number of tracepoints to the binder driver, and one (Eliot Courtney [KSDB]) contributed 23 commits, 19 of which were to the in-progress "nova" driver for NVIDIA GPUs. So Rust may be bringing in developers, but not yet in huge numbers yet.

Overall, the areas most frequently touched by new developers were:

Subsystem	# developers
Documentation	78
net	66
other drivers	52
drivers/net	49
drivers/staging	47
sound	46
include	36
drivers/gpu/drm	35
other fs	33
tools	32
arch/arm64	26
kernel	25
fs/smb	19
drivers/usb	17
drivers/iio	15
drivers/hwmon	13
drivers/bluetooth	10
MAINTAINERS	10
drivers/platform	10
drivers/i2c	9
mm	8

There are some interesting patterns here. The crowd of new developers working on the documentation is nice on its face .... but see "typo fixes", above. The number of first-timers changing the MAINTAINERS file could be of concern; there has been an episode or two recently where an unknown developer tried to claim maintainership of a subsystem, a prospect that is worrisome for obvious reasons. In this case, roughly half of the MAINTAINERS changes accompanied new drivers submitted by the new developer in question. There are a couple of previously unseen developers who showed up and claimed the maintainership of an existing subsystem, but they used email addresses from the company involved and, at a first glance, look legitimate. Meanwhile, the staging tree was meant to be a way for new developers to enter the community; it appears to still be serving that purpose.

One number that stands out is the number of new developers contributing to the SMB filesystem. These developers are not fixing typos; instead, they are addressing what appear to be serious, perhaps security-relevant bugs. Whether these developers are running their own tools to find bugs, or whether instead there is some sort of organized effort to direct new developers at those bugs is unclear. What does seem clear is that anybody who is using SMB in a setting where security matters may want to apply extra diligence to following kernel updates for a while.

As the numbers in the first part of this article show, the kernel's development process appears to be rolling along at its usual fast pace — or even a bit faster. But things are changing. New development tools have facilitated the entry of a large crowd of new developers into the community. If enough of them stay around, it should not take long to change the makeup of the kernel community — and how that community works — substantially. We live in interesting times.