2.6.39 development statistics

There have been just over 10,000 non-merge changesets merged for 2.6.39; with the sole exception of 2.6.37 (11,446 changesets), that's the highest since 2.6.33. Those changes came from 1,236 developers; only 2.6.37 (with 1,276 developers) has ever exceeded that number. Those developers added 670,000 lines of code while deleting 346,000 lines, for a net growth of 324,000 lines. The most active contributors this time around were:

Most active 2.6.39 developers

By changesets Thomas Gleixner 442 4.4% David S. Miller 201 2.0% Mike McCormack 138 1.4% Mark Brown 127 1.3% Tejun Heo 119 1.2% Russell King 89 0.9% Arnaldo Carvalho de Melo 86 0.9% Arend van Spriel 77 0.8% Al Viro 73 0.7% Aaro Koskinen 72 0.7% Tomas Winkler 70 0.7% Greg Kroah-Hartman 69 0.7% Chris Wilson 65 0.6% Joe Perches 60 0.6% Mauro Carvalho Chehab 60 0.6% Borislav Petkov 60 0.6% Eric Dumazet 59 0.6% Uwe Kleine-König 59 0.6% Dan Carpenter 59 0.6% Artem Bityutskiy 58 0.6%

By changed lines Wey-Yi Guy 45680 5.6% Wei Wang 25224 3.1% Alan Cox 20880 2.6% Laurent Pinchart 20459 2.5% Guan Xuetao 20167 2.5% Larry Finger 14763 1.8% Tomas Winkler 14095 1.7% Arnd Bergmann 13748 1.7% Igor M. Liplianin 13491 1.7% Aaro Koskinen 13274 1.6% Russell King 12862 1.6% Mike McCormack 11582 1.4% Jozsef Kadlecsik 10374 1.3% George 10353 1.3% Bhanu Gollapudi 9925 1.2% Thomas Gleixner 8869 1.1% Olivier Grenie 8167 1.0% Greg Ungerer 8105 1.0% Sakari Ailus 7513 0.9% Joe Perches 7048 0.9%

Thomas Gleixner got to the top of the per-changesets list with a massive reworking of how interrupts are managed in the kernel - a job which required significant changes in almost every architecture. David Miller did a great deal of work cleaning up, reworking, and optimizing the networking stack. Mike McCormack did a lot of cleanup work on the rtl8192e driver in the staging tree, Mark Brown contributed the usual large pile of changes concentrated in the sound driver subsystem, and Tejun Heo improved things all over the tree, primarily in the x86 architecture code.

On the lines-changed side, Wey-Yi Guy reworked some Intel network drivers, Wei Wang worked on the Realtek card reader driver in the staging tree, Alan Cox added the GMA500 driver to staging, Laurent Pinchart did a bunch of Video4Linux work including the addition of the media controller subsystem, and Guan Xuetao added the unicore32 architecture.

There were just over 200 known employers supporting work on the 2.6.39, the most active of which were:

Most active 2.6.39 employers

By changesets (None) 1374 13.7% Red Hat 1260 12.6% (Unknown) 690 6.9% Intel 571 5.7% Novell 376 3.7% Texas Instruments 372 3.7% IBM 305 3.0% Nokia 297 3.0% linutronix 276 2.8% (Consultant) 203 2.0% Google 180 1.8% Broadcom 180 1.8% Atheros 151 1.5% Samsung 150 1.5% Wolfson Micro 146 1.5% AMD 133 1.3% Pengutronix 123 1.2% ST Ericsson 116 1.2% LINBIT 111 1.1% Oracle 99 1.0%

By lines changed Intel 117903 14.6% (None) 94093 11.6% Red Hat 52140 6.4% Nokia 46063 5.7% Texas Instruments 39536 4.9% (Unknown) 37755 4.7% Realsil Micro 25370 3.1% IBM 24121 3.0% (Consultant) 23999 3.0% Broadcom 23330 2.9% Peking University 20487 2.5% Novell 19024 2.3% Samsung 17275 2.1% NetUP 13683 1.7% Google 11201 1.4% Realtek 10457 1.3% KFKI Research Inst 10430 1.3% Ericsson 9199 1.1% ST Ericsson 8611 1.1% Freescale 8457 1.0%

The percentage of changes coming from developers known to be working on their own time is at the lowest level seen since we started generating these statistics. Whether that means that volunteers are slowly losing interest in working with the kernel or that everybody who can do kernel work has been hired is hard to say.

Red Hat, as always, generates large numbers of patches; Texas Instruments continues the steady increase we have seen over the last few years, while Oracle continues to decline. New entries this time around include Realsil (the Realtek card reader work), the Peking University Microprocessor R&D Laboratory (the unicore32 architecture), NetUP (various drivers), and the KFKI Research Institute (ipset).

Occasionally it is interesting to look at the list of non-author signoffs - Signed-off-by tags added by developers who are not the authors of the patches involved. For 2.6.39, that list looks like this:

Developers with the most signoffs (total 8766)
Greg Kroah-Hartman	1162	13.3%
David S. Miller	546	6.2%
John W. Linville	437	5.0%
Mauro Carvalho Chehab	434	5.0%
Andrew Morton	317	3.6%
James Bottomley	220	2.5%
Ingo Molnar	186	2.1%
Mark Brown	158	1.8%
Sascha Hauer	135	1.5%
Tony Lindgren	129	1.5%
Takashi Iwai	124	1.4%
Samuel Ortiz	106	1.2%
Paul Mundt	100	1.1%
Matthew Garrett	99	1.1%
Russell King	98	1.1%
Jeff Kirsher	97	1.1%
Jiri Kosina	95	1.1%
Linus Torvalds	94	1.1%
Patrick McHardy	90	1.0%
Konrad Rzeszutek Wilk	89	1.0%

Greg Kroah-Hartman contributed "only" 69 patches to 2.6.39, but another 1,162 - over 13% of the total - passed through his hands on their way into the kernel. The bulk of those changes applied to the staging tree, but they were certainly not limited to staging. Linus Torvalds directly merged only 94 changes from others; everything else came in by way of a subsystem maintainer's tree.

Despite being one of the more active development cycles in recent years, 2.6.39 has also been one of the smoothest. The number of difficult regressions has been small, and, if Linus's current plan holds, the cycle could complete in just over 60 days, which would make it the shortest development cycle since the beginning of the git era. Kernel development is not without its glitches, but the process would appear to be working quite smoothly.

(As always, thanks are due to Greg Kroah-Hartman for his help in the creation of these statistics.)