Statistics from the 3.4 development cycle

As of this writing, Linus has merged just over 10,700 changes for 3.4; those changes were contributed from 1,259 developers. The total growth of the kernel source this time around is 215,000 lines. The developers most active in this cycle were:

Most active 3.4 developers

By changesets Mark Brown 284 2.7% Russell King 211 2.0% Johannes Berg 147 1.4% Al Viro 136 1.3% Axel Lin 133 1.2% Johan Hedberg 122 1.1% Guenter Roeck 121 1.1% Masanari Iida 109 1.0% Stanislav Kinsbursky 97 0.9% Trond Myklebust 85 0.8% Jiri Slaby 82 0.8% Ben Hutchings 82 0.8% Greg Kroah-Hartman 78 0.7% Takashi Iwai 78 0.7% Dan Carpenter 78 0.7% Stephen Warren 76 0.7% Stanislaw Gruszka 76 0.7% Alex Deucher 73 0.7%

By changed lines Joe Perches 56571 8.1% Dan Magenheimer 24077 3.4% Stephen Rothwell 17354 2.5% Greg Kroah-Hartman 15015 2.1% Mark Brown 12266 1.8% Jiri Olsa 11842 1.7% Mark A. Allyn 10976 1.6% Stephen Warren 10386 1.5% Arun Murthy 9347 1.3% Ingo Molnar 8779 1.3% Alex Deucher 8770 1.3% David Howells 8034 1.2% Guenter Roeck 7634 1.1% Chris Kelly 7023 1.0% Johannes Berg 6657 1.0% Ben Hutchings 6650 1.0% Al Viro 6628 0.9% Russell King 6610 0.9%

Mark Brown finds himself at the top of the list of changeset contributors for the second cycle in a row; as usual, he has done a great deal of work with sound drivers and related subsystems. Russell King is the chief ARM maintainer; he has also taken an active role in the refactoring and cleanup of the ARM architecture code. Johannes Berg continues to do a lot of work with the mac80211 layer and the iwlwifi driver, Al Viro has been improving the VFS API and fixing issues throughout the kernel, and Axel Lin has done a lot of cleanup work in the ALSA and regulator subsystems and beyond.

Joe Perches leads the "lines changed" column with coding-style fixes, pr_*() conversions, and related work. Dan Magenheimer added the "ramster" memory sharing mechanism to the staging tree. Linux-next maintainer Stephen Rothwell made it into the『lines changed』column with the removal of a lot of old PowerPC code. Greg Kroah-Hartman works all over the tree, but the bulk of his changed lines were to be found in the staging tree.

Some 195 companies contributed changes during the 3.4 development cycle. The top contributors this time around were:

Most active 3.4 employers

By changesets (None) 1156 10.8% Intel 1138 10.6% Red Hat 960 9.0% (Unknown) 688 6.4% Texas Instruments 428 4.0% IBM 381 3.6% Novell 372 3.5% (Consultant) 298 2.8% Wolfson Microelectronics 286 2.7% Samsung 234 2.2% Google 222 2.1% Oracle 188 1.8% Freescale 175 1.6% Qualcomm 161 1.5% Linaro 143 1.3% Broadcom 140 1.3% NetApp 133 1.2% MiTAC 133 1.2% AMD 132 1.2%

By lines changed (None) 108509 15.5% Intel 67464 9.7% Red Hat 65966 9.4% (Unknown) 50900 7.3% IBM 36800 5.3% Oracle 26617 3.8% Texas Instruments 25687 3.7% Samsung 24966 3.6% NVidia 20604 2.9% Linux Foundation 16917 2.4% ST Ericsson 15792 2.3% Novell 15185 2.2% Wolfson Microelectronics 14039 2.0% (Consultant) 13495 1.9% AMD 10151 1.5% Freescale 10102 1.4% Linaro 9360 1.3% Google 9070 1.3% Qualcomm 8972 1.3%

A longstanding invariant in the above table has been Red Hat as the top corporate contributor; in 3.4, however, Red Hat has been pushed down one position by Intel. Red Hat's contributions are down somewhat; 960 changesets in 3.4 compared to 1,290 in 3.3. But the more significant change is the burst of activity from Intel. This work is mostly centered around support for Intel's own hardware, as one would expect, but also extends to things like support for the x32 ABI. Meanwhile, Texas Instruments continues the growth in participation seen over the last few years, as do a number of other mobile and embedded companies. Once upon a time, it was said that Linux development was dominated by "big iron" enterprise-oriented companies; those companies have not gone away, but they are clearly not the only driving force behind Linux kernel development at this point. On the other hand, the participation by volunteers is at the lowest level seen in many cycles, continuing a longstanding trend.

A brief focus on ARM

Recent development cycles have seen a lot of work in the ARM subtree, and 3.4 is no exception; 1,100 changesets touched code in arch/arm this time around. Those changes were contributed by 178 developers representing 51 companies. Among those companies, the most active were:

Most active 3.4 employers (ARM subtree)
By changesets (Consultant) 149 13.5% Texas Instruments 121 11.0% (None) 103 9.4% Samsung 91 8.3% Linaro 80 7.3% NVidia 54 4.9% ARM 52 4.7% (Unknown) 48 4.4% Calxeda 46 4.2% Freescale 40 3.6% Atmel 37 3.4% Atomide 30 2.7% OpenSource AB 24 2.2% Google 23 2.1% ST Ericsson 23 2.1%	By lines changed Samsung 8162 16.8% (None) 5967 12.3% NVidia 4929 10.2% (Consultant) 4755 9.8% Linaro 3550 7.3% Texas Instruments 3118 6.4% ARM 2659 5.5% Calxeda 2408 5.0% Atmel 2080 4.3% (Unknown) 1862 3.8% Vista-Silicon S.L. 1121 2.3% Freescale 1117 2.3% Atomide 1005 2.1% Google 737 1.5% PHILOSYS Software 659 1.4%

ARM is clearly an active area for consultants, who contributed over 13% of the changes this time around. Otherwise, there are few surprises to be seen in this area; the companies working in the mobile area are the biggest contributors to the ARM tree, while those focused on other types of systems have little presence here.

There is one other way to look at ARM development. Much of the work on ARM is done through the Linaro consortium. Many developers contributing code from a linaro.com address are "on loan" from other companies; the above table, to the extent possible, credits those changes to the "real" employer that paid for the work. If, instead, all changes from a Linaro address are credited to Linaro, the results change: Linaro, with 11.9% of all the changes in arch/arm, becomes the top employer, though it still accounts for fewer changes than independent consultants do. Linaro clearly has become an important part of the ARM development community.

In summary, it has been another busy and productive development cycle in the kernel community. Despite the usual hiccups, things are stabilizing and chances are good that 3.4-rc7 will be the last prepatch, meaning that this cycle will be a relatively short one. There is little rest for kernel developers, though; the 3.5 cycle with its frantic merge window will start shortly thereafter. Stay tuned to LWN, as always, for ongoing coverage of development in this large and energetic community.