Kernel development statistics for 2.6.35

In the tradition of summarizing the statistics of the Linux kernel releases before the actual release of the kernel version itself, here is a summary of what has happened in the Linux kernel tree over the past few months.

This kernel release has seen 9460 changesets from about 1145 different developers so far. This continues the trend over the past few kernel releases for the size of both the changes as well as the development community as can be seen in this table:

Kernel	Patches	Devs
2.6.29	11,600	1170
2.6.30	11,700	1130
2.6.31	10,600	1150
2.6.32	10,800	1230
2.6.33	10,500	1150
2.6.34	9,100	1110
2.6.35	9,460	1145

Perhaps our years of increasing developer activity — getting more developers per release and more changes per release — has finally reached a plateau. If so, that is not a bad thing, as a number of us were wondering what the limits of our community were going to be. At around 10 thousand changes per release, that limit is indeed quite high, so there is no need to be concerned, as the Linux kernel is still, by far, the most active software development project the world has ever seen.

In looking at the individual developers, the quantity and size of contributions is still quite large:

Most active 2.6.35 developers

By changesets Mauro Carvalho Chehab 228 2.3% Dan Carpenter 135 1.3% Greg Kroah-Hartman 134 1.3% Arnaldo Carvalho de Melo 121 1.2% Johannes Berg 105 1.0% Ben Dooks 98 1.0% Julia Lawall 96 1.0% Hans Verkuil 92 0.9% Alexander Graf 84 0.8% Eric Dumazet 82 0.8% Peter Zijlstra 79 0.8% Paul Mundt 79 0.8% Johan Hovold 75 0.7% Tejun Heo 74 0.7% Stephen Hemminger 74 0.7% Mark Brown 71 0.7% Sage Weil 70 0.7% Alex Deucher 68 0.7% Randy Dunlap 67 0.7% Frederic Weisbecker 66 0.7%

By changed lines Uwe Kleine-König 194249 18.5% Ralph Campbell 53250 5.1% Greg Kroah-Hartman 31714 3.0% Stepan Moskovchenko 30037 2.9% Arnaud Patard 28783 2.7% Mauro Carvalho Chehab 27902 2.7% Eliot Blennerhassett 18490 1.8% Luis R. Rodriguez 16555 1.6% Daniel Mack 16176 1.5% Bob Beers 11703 1.1% Jason Wessel 10502 1.0% Viresh KUMAR 10499 1.0% Barry Song 10116 1.0% James Chapman 9645 0.9% Steve Wise 9580 0.9% Sjur Braendeland 8775 0.8% Alex Deucher 7721 0.7% Jassi Brar 7554 0.7% Sujith 7544 0.7% Giridhar Malavali 6867 0.7%

Uwe Kleine-König, who works for Pengutronix, dominates the "changed lines" list due to one patch that Linus just pulled for the 2.5.35-rc5 release that deleted almost all of the ARM default config files. Linus responded when Uwe posted his patch with:

Other than that major cleanup, the majority of the work was in drivers. Ralph Campbell did a lot of Infiniband driver work, I did a lot of cleanup on some staging drivers, and Stepan Moskovchenko and Arnaud Patard contributed new drivers to the staging tree. Mauro Carvalho Chehab contributed lots of Video for Linux driver work — rounding out the top 6 contributors by lines of code changed.

Continuing the view that this kernel is much like previous ones, 177 different employers were found to have contributed to the 2.6.35 kernel release:

Most active 2.6.35 employers

By changesets (None) 1429 14.2% Red Hat 1185 11.8% (Unknown) 904 9.0% Intel 637 6.3% Novell 559 5.6% IBM 295 2.9% Nokia 253 2.5% (Consultant) 215 2.1% Atheros Communications 175 1.7% AMD 173 1.7% Oracle 169 1.7% Samsung 163 1.6% Texas Instruments 162 1.6% (Academia) 140 1.4% Fujitsu 138 1.4% Google 122 1.2% Renesas Technology 102 1.0% Analog Devices 98 1.0% Simtec 96 1.0% NTT 93 0.9%

By lines changed Pengutronix 195175 18.6% Red Hat 82334 7.8% (None) 79313 7.6% (Unknown) 72426 6.9% QLogic 72131 6.9% Novell 49651 4.7% Intel 47260 4.5% Code Aurora Forum 40081 3.8% Mandriva 29105 2.8% Atheros Communications 29055 2.8% Samsung 25817 2.5% ST Ericsson 20463 2.0% Analog Devices 18889 1.8% AudioScience Inc. 18545 1.8% caiaq 16194 1.5% Nokia 14891 1.4% Texas Instruments 14864 1.4% (Consultant) 14209 1.4% IBM 12235 1.2% ST Microelectronics 11728 1.1%

But enough of the normal way of looking at the kernel as a whole body. Let's try something different this time, and break the contributions down by the different functional areas of the kernel.

The kernel is a bit strange in that it is a mature body of code that still changes quite frequently and throughout the whole body of code. It is not just drivers that are changing, but the "core" kernel as well. That is pretty unusual for a mature code base. The core kernel code — those files that all architectures and users use no matter what their configuration is — comprises 5% of the kernel (by lines of code), and you will find that 5% of the total kernel changes happen in that code. Here is the raw number of changes for the "core" kernel files for the 2.6.35-rc5 release.

Action	Lines	% of all changes
Added	27,550	4.50%
Deleted	7,450	1.90%
Modified	6,847	4.93%

Note that the percent deleted are a bit off because of the huge defconfig delete by Uwe as described above.

So, if the changes are made in a uniform way across the kernel, does that mean that the same companies contribute in a uniform way as well, or do some contribute more to one area than another?

I've broken the kernel files down into six different categories:

• core : This includes the files in the init, block, ipc, kernel, lib, mm, and virt subdirectories.
• drivers : This includes the files in the crypto, drivers, sound, security, include/acpi, include/crypto, include/drm, include/media, include/mtd, include/pcmcia, include/rdma, include/rxrpc, include/scsi, include/sound, and include/video subdirectories.
• filesystems : This includes the files in the fs subdirectory.
• networking : This includes the files in the net and include/net subdirectories.
• architecture-specific : This includes the files in the arch, include/xen, include/math-emu, and include/asm-generic subdirectories.
• miscellaneous : This includes all of the rest of the files not included in the above categories.

Category	% Lines
Core	4.37%
Drivers	57.06%
Filesystems	7.21%
Networking	5.03%
Arch-specific	21.92%
Miscellaneous	4.43%

Here are the top companies contributing to the different areas of the kernel:

Most active 2.6.35 employers (core)
By changesets Red Hat 218 16.5% (None) 148 11.2% IBM 66 5.0% Novell 60 4.5% Intel 59 4.5% (Unknown) 57 4.3% Fujitsu 33 2.5% Google 30 2.3% Wind River 22 1.7% Oracle 22 1.7% Nokia 22 1.7% (Consultant) 22 1.7%	By lines changed Wind River 9535 25.4% Red Hat 6277 16.7% Novell 2385 6.4% (None) 2074 5.5% IBM 2064 5.5% Intel 1480 3.9% Fujitsu 1431 3.8% Google 1417 3.8% VirtualLogix Inc. 992 2.6% ST Ericsson 957 2.6% caiaq 707 1.9% (Unknown) 614 1.6%

The companies contributing to the core kernel files are not surprising. These companies have all contributed to Linux for a long time, and it is part of their core strategy. Wind River has a high number of lines changed due to all of the KGDB work that Jason Wessel has been doing in getting that codebase cleaned up and merged into the main kernel tree.

Most active 2.6.35 employers (drivers)
By changesets (None) 1022 18.1% (Unknown) 678 12.0% Red Hat 528 9.4% Intel 499 8.9% Novell 336 6.0% Nokia 199 3.5% Atheros Communications 165 2.9% (Academia) 94 1.7% IBM 86 1.5% QLogic 86 1.5%	By lines changed QLogic 72122 12.2% (None) 61356 10.4% (Unknown) 60802 10.3% Red Hat 47204 8.0% Intel 39891 6.7% Novell 36951 6.2% Code Aurora Forum 34888 5.9% Mandriva 28867 4.9% Atheros Communications 28844 4.9% AudioScience Inc. 18535 3.1%

Because the drivers make up over 50% of the overall size of the kernel, the contributions here track the overall company statistics very closely. The company AudioScience Inc. sneaks onto the list of changes due to all of the work that Eliot Blennerhassett has been doing on the asihpi sound driver.

Most active 2.6.35 employers (filesystems)
By changesets Red Hat 134 15.9% Oracle 77 9.1% New Dream Network 76 9.0% Novell 76 9.0% (Unknown) 73 8.7% (None) 58 6.9% NetApp 42 5.0% Parallels 39 4.6% IBM 23 2.7% Univ. of Michigan CITI 23 2.7%	By lines changed Oracle 7194 24.2% Red Hat 6392 21.5% Novell 3989 13.4% (Unknown) 3081 10.4% (None) 2024 6.8% New Dream Network 1423 4.8% NetApp 897 3.0% Google 857 2.9% Parallels 687 2.3% (Consultant) 546 1.8%

Filesystem contributions, like drivers, match up with the different company strengths. New Dream Network might not be a familiar name to a lot of people, but their development on the Ceph filesystem pushed it into the list of top contributors. The University of Michigan did a lot of NFS work, bringing that organization into the top ten.

Most active 2.6.35 employers (networking)
By changesets SFR 74 9.6% (Consultant) 73 9.5% Red Hat 72 9.3% (None) 67 8.7% ProFUSION 55 7.1% Intel 45 5.8% Astaro 35 4.5% Vyatta 34 4.4% (Unknown) 34 4.4% Oracle 20 2.6% ST Ericsson 20 2.6% Univ. of Michigan CITI 20 2.6%	By lines changed Katalix Systems 9213 24.2% ST Ericsson 8003 21.0% (Consultant) 3691 9.7% Univ. of Michigan CITI 2334 6.1% Astaro 1956 5.1% Red Hat 1882 4.9% Intel 1607 4.2% SFR 1555 4.1% ProFUSION 1065 2.8% (None) 1060 2.8% (Unknown) 1035 2.7%

Like the filesystem list, networking also shows the University of Michigan's large contributions as well as many of the other common Linux companies. But here a number of not-so-familiar companies start showing up.

SFR is a French mobile phone company, and contributed lots of changes all through the networking core. ProFUSION is an embedded development company that did a lot of Bluetooth development for this kernel release. Katalix Systems is another embedded development company and they contributed a lot of l2tp changes. Astaro is a networking security company that contributed a number of netfilter changes.

Most active 2.6.35 employers (architecture-specific)
By changesets Red Hat 146 7.2% (None) 143 7.0% IBM 120 5.9% Novell 109 5.4% Samsung 100 4.9% Texas Instruments 94 4.6% AMD 90 4.4% Simtec 85 4.2% (Unknown) 75 3.7% (Consultant) 73 3.6%	By lines changed Pengutronix 194211 60.5% Samsung 15341 4.8% ST Microelectronics 10038 3.1% (None) 8338 2.6% Red Hat 7981 2.5% (Consultant) 6695 2.1% IBM 6064 1.9% Novell 5973 1.9% Code Aurora Forum 5114 1.6% Analog Devices 4345 1.4%

With the architecture-specific files taking up the second largest chunk of code in the kernel, the list of contributing companies is closer to the list of overall contributors as well, with more hardware companies showing that they contribute a lot of development to get Linux working properly on their specific processors.

Most active 2.6.35 employers (miscellaneous)
By changesets Red Hat 206 26.9% (None) 110 14.4% (Unknown) 35 4.6% Novell 28 3.7% Intel 27 3.5% IBM 18 2.4% Fujitsu 16 2.1% Google 15 2.0% Wind River 9 1.2% (Academia) 9 1.2% Vyatta 9 1.2%	By lines changed Red Hat 12772 34.0% Broadcom 6082 16.2% (None) 5156 13.7% (Unknown) 2757 7.3% Intel 2212 5.9% (Academia) 1850 4.9% Samsung 769 2.1% Wind River 593 1.6% Fujitsu 592 1.6% Nokia 532 1.4% IBM 499 1.3%

The rest of the various kernel files that don't fall into any other major category show that Red Hat has done a lot of work on the userspace performance monitoring tools that are bundled with the Linux kernel.

As for overall trends in the different categories, Red Hat shows that they completely dominate all areas of developing the Linux kernel when it comes to the number of contributions. No other company shows up in the top ten contributors for all categories like they do. But, by breaking out the kernel contributions in different areas of the kernel, we see that a number of different companies are large contributors in different, important areas. Normally these contributions get drowned out by the larger contributors, but the more specialized contributors are just as important to advancing the Linux kernel.