Some 3.13 development statistics

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As of this writing, the current development kernel snapshot is 3.13-rc6. Linus has said that this cycle will almost certainly go to -rc8, even if things look stable (as they indeed do) to avoid opening the merge window while he is attending linux.conf.au. Your editor, wishing to avoid writing highly technical articles during that period for exactly the same reason, deems this the right time for our traditional, non-technical look at the 3.13 development cycle and where the patches came from this time around.

There have been just under 12,000 non-merge changesets pulled into the mainline kernel for 3.13 so far; the total will almost certainly exceed 12,000 by the time the final release happens. 3.13 is thus a significantly busier cycle than its immediate predecessors; indeed, only three previous cycles (2.6.25, 3.8, and 3.10) have brought in more changes. Those changes, which added 446,000 lines and deleted 241,000 for a net growth of 205,000 lines, were contributed by 1,339 developers. The most active of those developers were:

Most active 3.13 developers

By changesets Sachin Kamat 361 3.0% Jingoo Han 323 2.7% Marcel Holtmann 225 1.9% Viresh Kumar 169 1.4% Lars-Peter Clausen 150 1.3% H Hartley Sweeten 147 1.2% Ville Syrjälä 145 1.2% Joe Perches 135 1.1% Mark Brown 122 1.0% Takashi Iwai 120 1.0% Lee Jones 113 0.9% Linus Walleij 103 0.9% Peter Zijlstra 92 0.8% Wei Yongjun 88 0.7% Ben Widawsky 88 0.7% Al Viro 87 0.7% Ian Abbott 85 0.7% Russell King 83 0.7% Thierry Reding 80 0.7% Ingo Molnar 76 0.6%

By changed lines Ben Skeggs 19014 3.5% Greg Kroah-Hartman 17378 3.2% Jovi Zhangwei 16377 3.0% Guenter Roeck 13013 2.4% Eugene Krasnikov 10082 1.8% Patrick McHardy 8863 1.6% Joe Perches 7076 1.3% Ralf Baechle 6687 1.2% Archit Taneja 6246 1.1% Akhil Bhansali 6214 1.1% Aaro Koskinen 6164 1.1% Ard Biesheuvel 5814 1.1% Dave Chinner 5311 1.0% David Howells 5287 1.0% Russell King 5125 0.9% Hisashi Nakamura 4605 0.8% Ian Abbott 4452 0.8% Kent Overstreet 4349 0.8% Thierry Escande 4236 0.8% Jens Axboe 3745 0.7%

Sachin Kamat's and Jongoo Han's extensive janitorial work throughout the driver subsystem put them in the top two positions for changesets merged for the second cycle in a row. Marcel Holtmann did extensive surgery in the Bluetooth layer, Viresh Kumar did a lot of cleanup work in the cpufreq subsystem, and Lars-Peter Clausen did a lot of development in the driver tree, focusing especially on industrial I/O and audio drivers.

In the "lines changed" column, Ben Skeggs's work is concentrated, as always, on the nouveau driver. Greg Kroah-Hartman and Jovi Zhangwei do not properly belong on the list this month; they show up as a result of the addition of ktap to the staging tree (by Jovi) and its subsequent removal (by Greg). Guenter Roeck removed support for the Renesas H8/300 architecture, and Eugene Krasnikov contributed a single patch adding a driver for Qualcomm WCN3660/WCN3680 wireless adapters. Patrick McHardy's #6 position, resulting from the addition of the nftables subsystem, also merits a mention.

A minimum of 217 companies supported work on the 3.13 kernel; the most active of those were:

Most active 3.13 employers

By changesets Intel 1428 11.9% (None) 1323 11.1% Linaro 1166 9.7% Red Hat 1082 9.0% Samsung 594 5.0% (Unknown) 570 4.8% IBM 419 3.5% (Consultant) 342 2.9% SUSE 328 2.7% Texas Instruments 263 2.2% Outreach Program for Women 218 1.8% Freescale 206 1.7% Google 198 1.7% NVidia 180 1.5% Vision Engraving Systems 147 1.2% Oracle 135 1.1% Renesas Electronics 123 1.0% Free Electrons 121 1.0% Huawei Technologies 119 1.0% ARM 111 0.9%

By lines changed Red Hat 63583 11.7% Intel 59780 11.0% (None) 51458 9.4% 11.0% Linaro 32054 5.9% (Unknown) 26712 4.9% Texas Instruments 20219 3.7% Linux Foundation 18262 3.4% Huawei Technologies 18182 3.3% IBM 15435 2.8% (Consultant) 14802 2.7% Samsung 14739 2.7% Ericsson 13722 2.5% NVidia 10884 2.0% Astaro 8863 1.6% Wind River 8421 1.5% Renesas Electronics 7337 1.3% SUSE 7230 1.3% Fusion-IO 6956 1.3% Western Digital 6590 1.2% Nokia 6479 1.2%

The percentage of contributions from volunteers is up a bit this time around, but not by enough to suggest any real change in its long-term decline. Perhaps the biggest surprise here, though, is that, for the first time, Red Hat has been pushed down in the "by changesets" column by Linaro. If there was ever any doubt that the mobile and embedded industries are playing an ever larger role in the development of the kernel, this should help to dispel them. That said, if one looks at the employers of the subsystem maintainers who merged these patches, the picture looks a bit different:

Employers with the most non-author signoffs
Red Hat	2115	19.2%
Intel	1704	15.5%
Linux Foundation	1282	11.6%
Linaro	912	8.3%
Google	553	5.0%
Samsung	464	4.2%
(None)	403	3.7%
Texas Instruments	350	3.2%
Novell	348	3.2%
IBM	289	2.6%

The situation is changing here, with the mobile/embedded sector having a bigger presence than it did even one year ago, but, for the most part, entry into subsystem trees is still controlled by developers working for a relatively small number of mostly enterprise-oriented companies.

Finally, it can be interesting to look at first-time contributors — developers whose first patch ever went into 3.13. There were 219 of these first-time contributors in this development cycle. Your editor decided to look at the very first patch from each first-time contributor and see which files were touched. These changes are spread out throughout the kernel tree, but the most common places for first-time contributors to make their first changes in 3.13 were:

Directory	Contributors
drivers/staging	24
drivers/net	21
include	21
net	19
arch/arm	14
drivers/gpu	10
arch/powerpc	10
arch/x86	7
drivers/media	7
Documentation	7

One of the justifications behind the staging tree was that it would serve as an entry point for new developers; these numbers suggest that it is working. That said, if one looks at longer periods, more new contributors work in drivers/net than anywhere else.

Another interesting question is: what is the employment situation for first-time contributors to the kernel? Are new kernel hackers still volunteers, or do they have jobs already? The numbers are hazy, but there are still some conclusions that can be drawn:

Employer	Count
(Unknown)	97
Intel	21
Huawei Technologies	6
Samsung	6
Linaro	5
(None)	4
AMD	3
Texas Instruments	3
Outreach Program for Women	3

Another way to put this information is that 118 of the first-time contributors in 3.13 were working for companies, 97 of them were unknown, and four were known to be volunteers. Many (but not all) of the unknowns will eventually turn out to have been working on their own time. But, even if every single one of them were a volunteer, we would still have more first-time contributors coming from companies than working on their own. In a time when experienced kernel developers can be hard to hire, companies will have little choice but to grow their own; some companies, clearly, are working to do just that.

And that, in turn, suggests that the long-term decline in volunteer contributions may not be a big problem in the end. Getting code into the kernel remains a good way to get a job, but, it seems, quite a few developers are successful at getting the job first, and contributing afterward. With luck, that will help us to continue to have a stream of new developers coming into the kernel development community.

Index entries for this article
Kernel	Releases/3.13

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