Statistics from the 4.0 development cycle

The 4.0 kernel development cycle is heading toward its close; the final release can be expected on, mostly likely, April 12 (or possibly April 19 if a late regression turns up). This release will be notable for the new major version number, of course, even though the shift to 4.x does not mean anything more than "the minor numbers were getting too big." It may also be notable for being one of the slower development cycles in the last couple of years, though one should bear in mind that "slow" is used in a relative sense here.

To be specific, as of this writing, the 4.0 cycle has seen the addition of just over 10,000 non-merge changesets to the mainline repository. 1,403 developers have contributed to this release cycle so far; they have added 403,000 lines of code and removed 222,000 for a net growth of 181,000 lines. The list of the most active developers looks a bit different than it has in the last few cycles:

Most active 4.0 developers

By changesets Lars-Peter Clausen 179 1.8% Takashi Iwai 172 1.7% H Hartley Sweeten 153 1.5% Rickard Strandqvist 111 1.1% Antti Palosaari 95 0.9% Thierry Reding 94 0.9% Geert Uytterhoeven 88 0.9% Ian Abbott 88 0.9% Maxime Ripard 85 0.8% Michael S. Tsirkin 82 0.8% Marcel Holtmann 79 0.8% Ben Skeggs 77 0.8% Arnd Bergmann 76 0.8% Laurent Pinchart 75 0.7% Rasmus Villemoes 75 0.7% Al Viro 71 0.7% Trond Myklebust 71 0.7% Andy Shevchenko 66 0.7% Krzysztof Kozlowski 64 0.6% Christophe Ricard 62 0.6%

By changed lines Ben Skeggs 23587 4.8% Hans Verkuil 16433 3.3% Thomas Petazzoni 10642 2.1% Tero Kristo 9341 1.9% Hariprasad Shenai 8810 1.8% Michal Kazior 7878 1.6% H Hartley Sweeten 6925 1.4% Laurent Pinchart 6803 1.4% Dudley Du 5399 1.1% Takashi Iwai 5137 1.0% Antti Palosaari 4913 1.0% Boris Brezillon 4666 0.9% Christoph Hellwig 4365 0.9% Arnd Bergmann 3974 0.8% Rusty Russell 3963 0.8% Tony Lindgren 3960 0.8% Rickard Strandqvist 3921 0.8% Magnus Damm 3771 0.8% Andrzej Pietrasiewicz 3697 0.7% Maxime Ripard 3664 0.7%

For once, Hartley Sweeten's work on the Comedi drivers did not put him at the top of the "by changesets" list; that place was taken by Lars-Peter Clausen, who worked mostly in the audio and media driver trees. Takashi Iwai's work remains entirely within the audio subsystem tree. Below Hartley, Richard Strandqvist cleaned up a lot of dead code throughout the tree, while Antti Palosaari did a lot of work in the media driver subsystem.

In the "lines changed" column, Ben Skeggs carried out a massive renaming of symbols in the Nouveau driver; "nouveau" became "nvkm" in the parts of the code that make up the direct-rendering kernel module. Hans Verkuil continues to do work throughout the media subsystem; the bulk of his changed lines, though, took the form of removing some old, unloved drivers. Thomas Petazzoni added a number of framebuffer drivers to the staging tree, Tero Kristo cleaned up and enhanced the TI OMAP clock subsystem, and Hariprasad Shenai did a bunch of work on the cxgb4 network/InfiniBand drivers.

For some years, work on the staging tree has tended to dominate these two lists, but that is not the case for 4.0. Indeed, this is one of the slowest development cycles for the staging tree in general, as can be seen in the plot below:

The slow traffic in the staging tree explains much of the relative slowness of the 4.0 development cycle in general.

There are 197 employers who are known to have supported development of the 4.0 kernel. The most active of these were:

Most active 4.0 employers

By changesets Intel 1164 11.6% (None) 864 8.6% (Unknown) 712 7.1% Red Hat 703 7.0% SUSE 463 4.6% Linaro 401 4.0% Samsung 361 3.6% (Consultant) 336 3.3% Free Electrons 251 2.5% IBM 226 2.2% Renesas Electronics 188 1.9% Freescale 165 1.6% Google 154 1.5% Vision Engraving Systems 153 1.5% Primary Data 149 1.5% AMD 142 1.4% Texas Instruments 139 1.4% Oracle 137 1.4% Qualcomm 120 1.2% ARM 119 1.2%

By lines changed Intel 49062 9.9% Red Hat 46588 9.4% (None) 34171 6.9% Samsung 23835 4.8% Free Electrons 22943 4.6% Texas Instruments 22395 4.5% (Unknown) 22369 4.5% Cisco 19438 3.9% Linaro 17553 3.5% SUSE 11764 2.4% Renesas Electronics 10796 2.2% (Consultant) 10719 2.2% Chelsio 10439 2.1% IBM 10355 2.1% Code Aurora Forum 9697 2.0% Tieto 8115 1.6% ARM 7316 1.5% Vision Engraving Systems 6925 1.4% Qualcomm 6850 1.4% AMD 6781 1.4%

In the 3.19 development statistics article, we noted that developers with no affiliation (volunteers) were holding steady at about 11% of the total changeset contribution. The accompanying suggestion that the decline in volunteer developers could be ending may have been premature, though; in 4.0, only 8.6% of the (relatively low) changeset count came from volunteers. That is the lowest point since 3.10 and the second-lowest ever.

Otherwise, there is not much that jumps out from the above table; corporate support for kernel development doesn't change a whole lot from one development cycle to the next.

As of this writing, there are about 6,500 non-merge changesets in the linux-next tree, putting linux-next in a place similar to where it was at this point in the 3.19 development cycle. That suggests that, unless things change, 4.1 will be another relatively slow cycle — though, it bears repeating, the incorporation of over 10,000 changes in a development cycle lasting less than three months is not all that slow. Even if we are not setting records at the moment, it seems clear that the kernel development community remains strong and active.

Index entries for this article
Kernel	Releases/4.0

---

to post comments