Who wrote 2.6.37

The 2.6.37 development cycle is coming to a close; that must mean that it is time to look at the development statistics for this release. 2.6.37 has been a more active cycle than most, with 11,220 non-merge changesets added (as of 2.6.37-rc7). Only three cycles have seen more changes: 2.6.25 (12,243 changesets), 2.6.29 (11,678), and 2.6.30 (11,989). The relatively slow period since 2.6.33 appears to have come to an end.

The 2.6.36 kernel was unique in that it was actually smaller than its predecessor. 2.6.37 does not continue that trend; some 1,140,000 lines of code were added, and 641,000 lines were removed, for a net growth of 494,000 lines. Most notably, perhaps: the 2.6.37 kernel includes patches from 1,250 developers, the highest ever. The development community, clearly, is active and growing.

The most active contributors this time around were:

Most active 2.6.37 developers

By changesets Chris Wilson 211 1.9% Greg Kroah-Hartman 171 1.5% Eric Dumazet 166 1.5% Johannes Berg 149 1.3% Thomas Gleixner 147 1.3% Paul Mundt 140 1.2% Mauro Carvalho Chehab 122 1.1% Joe Perches 107 1.0% Avi Kivity 105 0.9% Mark Brown 100 0.9% Hans Verkuil 100 0.9% Namhyung Kim 100 0.9% Dan Carpenter 99 0.9% Christoph Hellwig 93 0.8% Jean Delvare 88 0.8% Axel Lin 88 0.8% Daniel Vetter 87 0.8% Vasiliy Kulikov 86 0.8% Arnd Bergmann 86 0.8% Julia Lawall 84 0.7%

By changed lines Henry Ptasinski 143303 9.6% Greg Kroah-Hartman 100861 6.7% Vipin Mehta 92398 6.2% Luis R. Rodriguez 71636 4.8% Mark Brown 53690 3.6% David Cross 48198 3.2% Dmitry Kravkov 47198 3.1% Larry Finger 40378 2.7% Krishna Gudipati 38712 2.6% Stefan Richter 29434 2.0% Stephen Hemminger 28504 1.9% Rasesh Mody 22335 1.5% Prashant P. Shah 15086 1.0% Michael Chan 14118 0.9% Christian Lamparter 13530 0.9% Liam Girdwood 13324 0.9% William Hubbs 12971 0.9% Vinod Koul 12944 0.9% Marek Belisko 11531 0.8% Al Cho 10097 0.7%

These lists feature a combination of old and new names. Chris Wilson got to the top of the by-changesets list by virtue of his work with the Intel graphics drivers. Greg Kroah-Hartman worked on the USB and TTY subsystems, but the bulk of his changes were made to the staging tree, and the new brcm80211 driver in particular. Eric Dumazet has been active all over the networking layer, Johannes Berg has been busy with wireless networking, and Thomas Gleixner rewrote the generic interrupt handling code (among many other things).

Looking at lines changed: Henry Ptasinski arrived at the top of the list through the addition of the brcm80211 driver which, as can be seen, is not a small piece of code. Vipin Mehta added the ath6kl driver to the staging tree, Luis Rodriguez worked on the mac80211 layer and the ath9k driver, and Mark Brown, as always, did a massive amount of work within the ALSA sound layer. It's interesting to note that five of the top ten in this column were mainly involved with the staging tree. One of the others (Krishna Gudipati) submitted a single "driver cleanup patch" which drew Linus's ire at the time - calling a nearly 40,000-line patch a "cleanup" seemed like a bit much.

A minimum of 193 employers supported work on the 2.6.37 kernel; the top supporters were:

Most active 2.6.37 employers

By changesets (None) 1864 16.6% Red Hat 1265 11.3% (Unknown) 946 8.4% Intel 746 6.6% Novell 644 5.7% IBM 447 4.0% Oracle 272 2.4% Texas Instruments 250 2.2% Nokia 235 2.1% Renesas Technology 210 1.9% Samsung 205 1.8% Broadcom 172 1.5% Societe Française de Radiotelephone 166 1.5% AMD 163 1.5% (Consultant) 155 1.4% Pengutronix 154 1.4% (Academia) 146 1.3% Wolfson Micro 129 1.1% Google 128 1.1% Fujitsu 127 1.1%

By lines changed Broadcom 246749 16.4% (None) 188830 12.6% Atheros 165693 11.0% Novell 127476 8.5% Wolfson Micro 100196 6.7% Brocade 64012 4.3% (Unknown) 59325 4.0% Red Hat 59000 3.9% Intel 53893 3.6% Cypress Semiconductor 48241 3.2% Vyatta 30720 2.0% Texas Instruments 22874 1.5% Samsung 16771 1.1% IBM 16567 1.1% Nokia 14731 1.0% Renesas Technology 14488 1.0% (Consultant) 13592 0.9% Slimlogic Ltd 13324 0.9% ST Ericsson 13056 0.9% Chelsio 10770 0.7%

Looking at the by-changesets column, the situation looks mostly like business as usual. Red Hat remains, by far, the largest corporate contributor to the kernel. On the lines-changed side, instead, Red Hat had to settle for eighth place behind companies which, for the most part, have contributed a lot of driver code.

It has been some time since we looked at the reviewing and testing of code. In the 2.6.37 development cycle, the developers with the most Reviewed-by tags were:

Most active 2.6.37 reviewers
Ingo Molnar	86	12.6%
Christoph Hellwig	37	5.4%
Mike Christie	29	4.3%
Michael Chan	26	3.8%
Josh Triplett	22	3.2%
Daniel Vetter	21	3.1%
Chuck Lever	21	3.1%
H. Peter Anvin	20	2.9%
Konrad Rzeszutek Wilk	19	2.8%
Alex Elder	17	2.5%
Luciano Coelho	16	2.3%
Suresh Jayaraman	16	2.3%
Swen Schillig	16	2.3%
Michal Marek	15	2.2%
Jeff Layton	15	2.2%
Sam Ravnborg	15	2.2%
Wu Fengguang	12	1.8%
Francisco Jerez	12	1.8%
KOSAKI Motohiro	12	1.8%
Christoph Lameter	11	1.6%

As always, there is only so much that can be learned from these numbers; the bulk of all patch reviews do not lead to the addition of a Reviewed-by tag. On the other hand, there has been some real social pressure to credit users who test patches and report bugs:

Most credited 2.6.37 reporters and testers

Reported-by credits Stephen Rothwell 24 4.2% Randy Dunlap 21 3.7% Linus Torvalds 19 3.3% Ingo Molnar 15 2.6% Guennadi Liakhovetski 10 1.8% Jonathan Cameron 7 1.2% David Brownell 7 1.2% Sitsofe Wheeler 6 1.1% Andrew Morton 6 1.1% Dan Rosenberg 6 1.1% Jiri Slaby 5 0.9% Ben Greear 5 0.9% Eric Dumazet 4 0.7% Daniel Vetter 4 0.7% David S. Miller 4 0.7% Robin Holt 4 0.7% Andi Kleen 4 0.7% Dan Carpenter 4 0.7% Sachin Sant 4 0.7% Dr. David Alan Gilbert 4 0.7%

Tested-by: credits Wolfram Sang 15 4.1% Luciano Coelho 11 3.0% Kevin Hilman 10 2.7% Jeff Pieper 10 2.7% Will Deacon 9 2.5% Caglar Akyuz 8 2.2% Michael Williamson 8 2.2% Emil Tantilov 7 1.9% Randy Dunlap 6 1.6% Stephen Ko 6 1.6% Ben Greear 6 1.6% Eric Benard 5 1.4% Tuomas Katila 5 1.4% Maxim Levitsky 5 1.4% Ingo Molnar 4 1.1% Juuso Oikarinen 3 0.8% Jason Wessel 3 0.8% Kuninori Morimoto 3 0.8% Rabin Vincent 3 0.8% Ben Gardiner 3 0.8%

All told, there were 568 Reported-by and 366 Tested-by tag lines found in patches merged for 2.6.37. We are, it seems, slowly getting better at recognizing the people who are doing this crucially important work.

In summary, the kernel development process continues to look healthy. We have a great deal of activity from an increasing number of developers, while, it seems, keeping a reasonable lid on the number of regressions introduced. Whether the high patch rate will continue into 2.6.38 remains to be seen; as of this writing, there are just under 5,000 changes in linux-next. Unless the subsystem maintainers put more work into linux-next in the near future, the next development cycle could be relatively slow.

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