Where the 3.6 kernel came from

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As of this writing, the 3.6 development is nearing its close with the 3.6-rc7 prepatch having been released on September 23. There may or may not be a 3.6-rc8 before the final release, but, either way, the real 3.6 kernel is not far away. It thus seems like an appropriate time for our traditional look at what happened in this cycle and who the active participants were.

At the release of -rc7, Linus had pulled 10,153 non-merge changesets from 1,216 developers into the mainline. That makes this release cycle just a little slower than its immediate predecessors, but, with over 10,000 changesets committed, the development community has certainly not been idle. This development cycle is already slightly longer than 3.5 (which required 62 days) and may be as much as two weeks longer by the end, if another prepatch release is required. Almost 523,000 lines of code were added and almost 252,000 were removed this time around for a net growth of about 271,000 lines.

Most active 3.6 developers By changesets H Hartley Sweeten 460 4.5% Mark Brown 175 1.7% David S. Miller 154 1.5% Axel Lin 152 1.5% Johannes Berg 115 1.1% Al Viro 113 1.1% Hans Verkuil 111 1.1% Lars-Peter Clausen 90 0.9% Sachin Kamat 84 0.8% Daniel Vetter 83 0.8% Eric Dumazet 79 0.8% Rafael J. Wysocki 77 0.8% Guenter Roeck 76 0.7% Alex Elder 76 0.7% Guennadi Liakhovetski 75 0.7% Sven Eckelmann 75 0.7% Ian Abbott 74 0.7% Arik Nemtsov 74 0.7% Dan Carpenter 72 0.7% Shawn Guo 70 0.7% By changed lines Greg Kroah-Hartman 113897 18.3% Mark Brown 18761 3.0% H Hartley Sweeten 14362 2.3% John W. Linville 14177 2.3% Chris Metcalf 11419 1.8% Hans Verkuil 9493 1.5% Alex Williamson 7335 1.2% Pavel Shilovsky 6226 1.0% Sven Eckelmann 5694 0.9% Johannes Berg 5518 0.9% Alexander Block 5465 0.9% Kevin McKinney 5211 0.8% David S. Miller 4600 0.7% Christoph Hellwig 4512 0.7% Yan, Zheng 4481 0.7% Felix Fietkau 4433 0.7% Ola Lilja 4191 0.7% Johannes Goetzfried 4129 0.7% Vaibhav Hiremath 4087 0.7% Nicolas Royer 3989 0.6%

H. Hartley Sweeten is at the top of the changesets column this month as the result of a seemingly unending series of patches to get the Comedi subsystem ready for graduation from the staging tree. Mark Brown continues work on audio drivers and related code. David Miller naturally has patches all over the networking subsystem; his biggest contribution this time around was the long-desired removal of the IPv4 routing cache. Axel Lin made lots of changes to drivers in the regulator and MTD subsystems, among others, and Johannes Berg continues his wireless subsystem work.

Greg Kroah-Hartman pulled the CSR wireless driver into the staging tree to get to the top of the "lines changed" column, even though his 69 changesets weren't quite enough to show up in the left column. John Linville removed some old, unused drivers, making him the developer who removed the most code from the kernel this time around. Chris Metcalf added a number of new features to the Tile architecture subtree.

The list of developers credited for reporting problems is worth a look:

Top 3.6 bug reporters Fengguang Wu 44 7.7% Martin Hundebøll 21 3.7% David S. Miller 19 3.3% Dan Carpenter 17 3.0% Randy Dunlap 14 2.4% Bjørn Mork 11 1.9% Al Viro 10 1.7% Ian Abbott 9 1.6% Stephen Rothwell 9 1.6% Eric Dumazet 8 1.4%

What we are seeing here is clearly the result of Fengguang Wu's build and boot testing work. As Fengguang finds problems, he reports them and they get fixed before the wider user community has to deal with them. Coming up with 44 bug reports in just over 60 days is a good bit of work.

Some 208 companies (that we know of) contributed to the 3.6 kernel. The most active of these were:

Most active 3.6 employers By changesets (None) 1124 11.1% Red Hat 1035 10.2% Intel 884 8.7% (Unknown) 828 8.2% Vision Engraving Systems 460 4.5% Texas Instruments 418 4.1% Linaro 409 4.0% IBM 286 2.8% SUSE 282 2.8% Google 243 2.4% Wolfson Microelectronics 180 1.8% (Consultant) 167 1.6% Freescale 152 1.5% Ingics Technology 152 1.5% Samsung 143 1.4% Qualcomm 135 1.3% Cisco 127 1.3% Wizery Ltd. 125 1.2% NVidia 124 1.2% Oracle 122 1.2% By lines changed Linux Foundation 122520 19.7% (None) 63608 10.2% Red Hat 59662 9.6% Intel 37556 6.0% (Unknown) 25719 4.1% Texas Instruments 25533 4.1% Wolfson Microelectronics 23020 3.7% Vision Engraving Systems 14876 2.4% (Consultant) 12830 2.1% Linaro 11677 1.9% Tilera 11436 1.8% Cisco 11223 1.8% IBM 11006 1.8% Freescale 9630 1.6% SUSE 9035 1.5% Marvell 7984 1.3% Samsung 7621 1.2% OMICRON Electronics 7259 1.2% Etersoft 6236 1.0% Google 5673 0.9%

Greg Kroah-Hartman's move to the Linux Foundation has caused a bit of a shift in the numbers; the Foundation has moved up in the rankings at SUSE's expense. Beyond that, we see the continued growth of the embedded industry's participation, the continuing slow decline of hobbyist contributions, and an equally slow decline in contributions from "big iron" companies like Oracle and IBM.

Taking a quick look at maintainer signoffs — "Signed-off-by" tags applied by somebody other than the author — the picture is this:

Non-author Signed-off-by tags By developer Greg Kroah-Hartman 1232 14.1% David S. Miller 754 8.6% John W. Linville 376 4.3% Mauro Carvalho Chehab 323 3.7% Mark Brown 291 3.3% Andrew Morton 280 3.2% Ingo Molnar 173 2.0% Luciano Coelho 132 1.5% Johannes Berg 128 1.5% Gustavo Padovan 124 1.4% By company Red Hat 2323 26.6% Linux Foundation 1278 14.6% Intel 592 6.8% Google 428 4.9% (None) 411 4.7% Texas Instruments 359 4.1% Wolfson Microelectronics 292 3.3% SUSE 270 3.1% Samsung 230 2.6% IBM 189 2.2%

The last time LWN put up a version of this table was for 2.6.34 in May, 2010. At that time, over half the patches heading into the kernel passed through the hands of somebody at Red Hat or SUSE. That situation has changed a bit since then, though the list of developers contains mostly the same names. Once again, we are seeing the mobile and embedded industry on the rise.

All told, it looks like business as usual. There are a lot of problems to be solved in the kernel space, so vast numbers of developers are working to solve them. There appears to be little danger that Andrew Morton's famous 2005 prediction that "we have to finish this thing one day" will come true anytime in the near future. But, if we can't manage to finish the job, at least we seem to have the energy and resources to keep trying.

