True, 19.4 percent of all Linux kernel development done since September 2013 appears to have been done by individual developers, but the rest has all been created by corporate programmers. Leading the way were Intel employees with 10.5 percent of Linux code to their credit. Following Intel was Red Hat, 8.4 percent; Linaro, 5.6 percent; Samsung, 4.4 percent; IBM 3.2 percent; and SUSE, 3 percent. In short, as the Linux Foundation report observes, "well over 80% of all kernel development is demonstrably done by developers who are being paid for their work."
This report covers work completed through Linux kernel 3.18, with an emphasis on releases 3.11 to 3.18. Looking closely at the contributors, it's clear that x86 Linux is still the heart of Linux kernel development community. The presence of Linaro and Samsung also point out that ARM and Android respectively are getting their fair share of programmer time as well.
All together more than 4,000 developers from 200 companies have contributed to the kernel. Half of the kernel developers were contributing for the first time. That number may look large, and it is, but the Foundation also found that "there is still a relatively small number who are doing the majority of the work. In any given development cycle, approximately 1/3 of the developers involved contribute exactly one patch." Since the 2.6.11 release, the top ten developers have contributed 36,664 changes -- 8.2 percent of the total. The top thirty developers contributed just over 17 percent of the all the code.
What makes that even more impressive is that the Linux kernel community has been merging patches at an average rate of 7.71 patches per hour. That's not per day, that's per hour. The average days of development per release has decreased in the last year from 70 days to 66 days.
Some of the highlights include the O_TMPFILE option for the creation of temporary files, NFS 4.2 support, virtualization support on the ARM64 architecture with Xen and KVM, the "zswap" compressed swap cache, support for using GPU rendering engines independently of a graphical display, the multi=queue block layer for improved high-end disk I/O performance, the "nftables" firewall that will eventually replace iptables, the real-time earliest-deadline-first scheduler, a vast array of networking improvements, a major reworking of the control group subsystem, "file sealing" support for secure interprocess communication, and the "overlayfs" union file system. On top of this of course are hundreds of new drivers and thousands of fixes.
That's the good news. The troubling news is that the volume of contributions from unpaid developers has been in slow decline for many years. It was 14.6 percent in 2012 and 13.6 percent in 2013; now it is 11.8 percent.
Of course, this may just be a sign of Linux's success. Companies that may have nothing to do with technology per se now need experienced Linux engineers and programmers for their IT departments. The Linux Foundation thinks that's the most plausible reason. After all, "Kernel developers are in short supply, so anybody who demonstrates an ability to get code into the mainline tends not to have trouble finding job offers."
At the same time, just over half of first time Linux kernel developers were already working for a company. In particular, Intel, by a margin of three to one, is bringing new developers to Linux, while Samsung, IBM, Google, and Huawai are also helping new programmers get their start on Linux kernel development.
The Foundation has also found that the Linux kernel code review is tending to be done by companies. In order of sign offs, Red Hat led the way with 18.8 percent, followed by the Linux Foundation, 14.8 percent; Intel 12.2 percent; Linaro, 9.3 percent; Google, 5.8 percent; and Samsung, 5.2 percent.
Put it all together and what you see is a Linux that now, more than ever, is a Linux created by big business rather than volunteers.