Development statistics for the 5.11 kernel

The 5.11 kernel was released on February 14 — the most romantic sort of Valentine's day gift one could hope for. This kernel saw the merging of 14,340 changesets from 1,912 developers; it is certainly not the busiest development cycle we have seen recently, but it still saw a lot of activity. Read on for our traditional look at where the code merged for 5.11 came from.

The history of the 5.x kernels to date looks like this:

Release	Changesets	Developers
5.0	12,808	1,760
5.1	13,034	1,727
5.2	14,024	1,784
5.3	14,605	1,882
5.4	14,619	1,877
5.5	14,350	1,885
5.6	12,665	1,712
5.7	13,901	1,878
5.8	16,306	1,991
5.9	14,858	1,917
5.10	16,174	1,971
5.11	14,340	1,912

The 5.11 development cycle, thus, looks fairly average and unremarkable in general — a middle-of-the road 5.x kernel. That said, the number of developers involved remains over 1,900; 280 of those developers made their first kernel contribution during the 5.11 cycle. The 5.11 kernel contains 608,000 more lines of code than 5.10 did.

The most active 5.11 developers were:

Most active 5.11 developers

By changesets Lee Jones 497 3.5% Krzysztof Kozlowski 195 1.4% Thomas Gleixner 148 1.0% Christophe Leroy 135 0.9% Chuck Lever 133 0.9% Christoph Hellwig 132 0.9% Sakari Ailus 126 0.9% Arnd Bergmann 119 0.8% Ville Syrjälä 119 0.8% Jonathan Cameron 115 0.8% Gustavo A. R. Silva 93 0.6% Tom Rix 90 0.6% Andy Shevchenko 89 0.6% Geert Uytterhoeven 87 0.6% Johannes Berg 86 0.6% Alex Elder 83 0.6% Takashi Iwai 83 0.6% Christian König 82 0.6% Colin Ian King 81 0.6% Trond Myklebust 81 0.6%

By changed lines Huang Rui 269436 28.0% Bhawanpreet Lakha 81661 8.5% Lee Jones 17973 1.9% Oded Gabbay 14281 1.5% Jiaxin Yu 13408 1.4% Johannes Berg 9764 1.0% Sakari Ailus 9305 1.0% Ilya Dryomov 7528 0.8% Srinivas Kandagatla 6072 0.6% Jonathan Cameron 5958 0.6% Fabio Estevam 5913 0.6% Christian König 5789 0.6% Roman Li 5370 0.6% Arnd Bergmann 5084 0.5% Chuck Lever 4681 0.5% Thomas Gleixner 4672 0.5% Christoph Hellwig 4612 0.5% Jin Yao 4577 0.5% Jarkko Sakkinen 4575 0.5% Peter Geis 4521 0.5%

Lee Jones was the contributor of the largest number of changesets this time around; the bulk of that work went into fixing compiler warnings throughout the tree. Krzysztof Kozlowski continues to contribute cleanups and small improvements to drivers and devicetree files. Thomas Gleixner worked on a lot of low-level improvements, including the kmap_local() mechanism. Christophe Leroy did a lot of work in the PowerPC architecture code, and Chuck Lever contributed a large number of (mostly) NFS-server changes.

The largest code addition — by far — was by Huang Rui, who added yet another set of massive amdgpu header files; Bhawanpreet Lakha also worked on the AMD graphics drivers. Oded Gabbay added support for the Habana "Gaudi" processor, which inevitably included a set of large header files, and Jiaxin Yu added the mt8192 audio driver.

Work on the 5.11 kernel was supported by 225 companies that we were able to identify; that is a typical number. The most active of those companies were:

Most active 5.11 employers

By changesets Intel 1364 9.5% (Unknown) 1106 7.7% Linaro 1050 7.3% Red Hat 836 5.8% AMD 825 5.8% Huawei Technologies 766 5.3% Google 698 4.9% (None) 523 3.6% SUSE 451 3.1% IBM 432 3.0% NVIDIA 400 2.8% Facebook 390 2.7% Arm 313 2.2% Samsung 288 2.0% NXP Semiconductors 284 2.0% (Consultant) 255 1.8% Oracle 250 1.7% Linutronix 233 1.6% Renesas Electronics 222 1.5% Code Aurora Forum 205 1.4%

By lines changed AMD 382664 39.7% Intel 94102 9.8% Linaro 47288 4.9% (Unknown) 39747 4.1% (None) 28334 2.9% Google 25976 2.7% Red Hat 24926 2.6% MediaTek 19657 2.0% NVIDIA 18029 1.9% Huawei Technologies 17853 1.9% NXP Semiconductors 15108 1.6% IBM 14767 1.5% SUSE 14337 1.5% Facebook 13033 1.4% (Consultant) 12716 1.3% Code Aurora Forum 12491 1.3% Arm 10065 1.0% BayLibre 9688 1.0% Linutronix 8843 0.9% Texas Instruments 7916 0.8%

As usual, there are few surprises here. If there is any sort of trend to point out in these results, it is that contributions from hardware companies are slowly growing in proportion relative to those from software and support companies.

Drilling down

The above numbers are all relative to the kernel source tree as a whole. If one looks at specific subsystems, the picture changes a bit. The results at this level tend to be more variable from one release to the next, so it makes sense to look over a long time period. The following numbers, thus, are accumulated over the time since the 5.5 release in January 2020; they are, in other words, a first approximation of the work that was merged last year.

Much of the core kernel code lives in the kernel directory. The developers and companies most actively working in that directory during 2020 were:

Most active (kernel)
Developers Paul E. McKenney 250 9.0% Peter Zijlstra 140 5.1% Christoph Hellwig 110 4.0% Thomas Gleixner 105 3.8% Steven Rostedt 98 3.5% Yonghong Song 59 2.1% Marco Elver 58 2.1% Masami Hiramatsu 56 2.0% Eric W. Biederman 44 1.6% Andrii Nakryiko 40 1.4%	Companies Facebook 486 17.6% Intel 294 10.6% Google 274 9.9% Red Hat 228 8.2% Linutronix 161 5.8% (Unknown) 141 5.1% Linaro 121 4.4% (Consultant) 112 4.0% VMware 98 3.5% Arm 97 3.5%

Over the last few years, Facebook has become the home to an increasing number of core-kernel developers, to the point that the company contributes far more patches to the kernel directory than any other.

The picture shifts a bit if one looks at patches to the memory-management code, found in the mm subdirectory.

Most active (mm)
Developers Christoph Hellwig 82 5.4% Matthew Wilcox 65 4.3% David Hildenbrand 60 4.0% Wei Yang 57 3.8% Roman Gushchin 51 3.4% Andrey Konovalov 48 3.2% Johannes Weiner 45 3.0% Vlastimil Babka 36 2.4% John Hubbard 34 2.2% Alex Shi 30 2.0% Mike Rapoport 30 2.0%	Companies Red Hat 162 10.7% Google 156 10.3% Facebook 121 8.0% (Unknown) 117 7.7% Oracle 95 6.3% (Consultant) 85 5.6% (None) 75 5.0% SUSE 73 4.8% Alibaba 73 4.8% Huawei Technologies 71 4.7% Intel 68 4.5%

The picture for filesystems looks like this:

Most active (fs)
Developers Pavel Begunkov 343 5.8% Christoph Hellwig 322 5.4% Jens Axboe 264 4.4% Darrick J. Wong 244 4.1% Josef Bacik 228 3.8% Trond Myklebust 207 3.5% Nikolay Borisov 199 3.3% Al Viro 174 2.9% Eric Biggers 154 2.6% Qu Wenruo 145 2.4%	Companies Red Hat 1043 17.5% SUSE 788 13.2% Facebook 690 11.6% Oracle 547 9.2% Huawei Technologies 389 6.5% (Consultant) 365 6.1% Google 347 5.8% (None) 314 5.3% (Unknown) 285 4.8% Hammerspace 207 3.5%

Much of the "filesystem" work over last year has been focused on the rapidly developing io_uring subsystem and on core infrastructural work. Beyond that, XFS, Btrfs, and NFS were all areas of active development.

And if one looks at the networking subsystem, the results are:

Most active (net)
Developers Chuck Lever 188 4.1% Christoph Hellwig 169 3.7% Paolo Abeni 136 3.0% Florian Westphal 124 2.7% Eric Dumazet 115 2.5% Karsten Graul 106 2.3% Pablo Neira Ayuso 105 2.3% Johannes Berg 100 2.2% Vladimir Oltean 83 1.8% Xin Long 77 1.7%	Companies Red Hat 573 12.5% Google 430 9.4% Intel 383 8.3% (None) 308 6.7% (Unknown) 303 6.6% (Consultant) 238 5.2% Oracle 219 4.8% Mellanox 183 4.0% IBM 179 3.9% Huawei Technologies 172 3.7%

There are a couple of interesting results here. Chuck Lever shows up for his work on the RPC code used by the NFS filesystem, for example, while Christoph Hellwig's work was mostly driven by improvements he was making elsewhere in the tree; neither is normally seen as a core networking developer. Paolo Abeni and Florian Westphal both worked on the mostly under-the-radar upstreaming of the multipath TCP code, which has been long in coming.

One conclusion that can be drawn here is that core-kernel work is somewhat concentrated in a relatively small number of companies. That said, it is much less so than it was some years ago. It would appear that more companies working within Linux have come to the conclusion that their interests lie in working beyond the specific subsystems needed to make their own hardware work. That seems like a good thing for the long-term sustainability of the kernel.

Index entries for this article
Kernel	Releases/5.11

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