Many of you are probably familiar with Linux—perhaps through your favorite distribution and tools—and you may know about its history and original development by Linus Torvalds, but you may not realize the relentless pace of development that the project entails. And, those new to open source may not be familiar with its far-reaching influence and pervasive use.
In this article, we’ll highlight details of the continuous Linux kernel development process and look at some of the operating system’s successes.
Linux, which will celebrate its 30th anniversary in 2021, is arguably the most successful open source project in history. The Linux Foundation, which provides a neutral home for kernel development and support, states:
Linux is the world’s largest and most pervasive open source software project in the history of computing. The Linux kernel is the largest component of the Linux operating system and is charged with managing the hardware, running user programs, and maintaining the security and integrity of the whole system. It is this kernel which, after its initial release by Linus Torvalds in 1991, jumpstarted the development of Linux as a whole.
The 2017 Linux Kernel Report, written by Jonathan Corbet and Greg Kroah-Hartman, says “Linux has come to dominate nearly every market it enters, including cloud, mobile, embedded, and supercomputing. This remarkable and sustained growth wouldn’t be possible without the rapid evolution of the Linux kernel and dedication of the kernel community.” Kernel releases occur regularly every nine or ten weeks and deliver new features, device support, and improved performance and security.
The rate of change in the Linux kernel is generally high, but the recent 5.8 release set new records in terms of changes and contributions. LWN.net, which regularly reports on kernel development, states “By the time the work was done, 16,306 non-merge changesets had been pulled into the mainline repository for this release. That happens to be a record, beating the previous record-holder (4.9, released in December 2016) by 92 changesets.”
Other highlights of the 5.8 release, as noted by LWN.net:
- 1,991 developers contributed to Linux kernel 5.8, which is also a record.
- 304 developers contributed for the first time in this cycle.
- More than 924,000 lines of code were added.
- Around 371,000 lines were removed (for a net growth of more than 553,000 lines of code).
Calling this “a busy development cycle” is a bit of an understatement, and the seeming ease with which this volume of change occurs speaks to the efficiency of the development model that has grown up around the kernel.
Such a level of activity—sustained more or less over many years—is remarkable, and the open source tenets behind this collaborative project deserve a closer look. The Linux Kernel Report describes the following features as key to the kernel development process:
- Short release cycles.
- A distributed, hierarchical development model for process scalability.
- The right tools, namely Git.
- A consensus-oriented model.
- A strong “no regressions” rule.
- Corporate participation.
- No internal boundaries within the project.
Through almost 30 years of experience, Linux kernel developers have clearly built a successful development model and one that evolves in response to changing needs. This evolution can be seen, for example, in the implementation of a code of conduct aimed at making the community more open and inclusive and in the recent steps taken to remove exclusionary language.
As mentioned previously, Linux has come to dominate nearly every market it enters. In many areas, the existence and growth of Linux have shaped the industry landscape, and the lack of Linux has become impossible to imagine.
Specifically, Linux runs 90 percent of the public cloud workload, has 62 percent of the embedded market share, and runs 82 percent of the world’s smartphones, according to the 2017 Linux Kernel Report. Additionally:
- Since November 2017, all 500 of the world’s fastest supercomputers have run the Linux operating system, according to the TOP500 supercomputing list.
- Since 2019, the use of Linux has surpassed Windows on Microsoft’s Azure cloud, and it runs the vast majority of Amazon EC2 images, according to The Cloud Market statistics.
- The Android operating system, which is based on a modified Linux kernel, has been the best-selling OS on smartphones since 2011, according to Wikipedia.
- Linux can be found in modern cars in the form of Automotive Grade Linux (AGL), which Toyota adopted starting with the 2018 Camry and Subaru included in the 2020 Outback.
- Linux is helping modernize the mainframe.
- And, Linux provides the basis for safe and reliable components for critical infrastructure through the Civil Infrastructure Platform.
In short, Linux is everywhere, and its continued growth and success are due in great part to the strong open source principles on which it was founded. In the words of Linus Torvalds upon release of the 5.8 kernel, “give it a whirl.”
The Linux Foundation: Home of Linux and many other open source projects.
Linux Kernel Newbies: Information and resources for aspiring Linux kernel developers.
LWN.net: Coverage of Linux and free software development.
Zack’s Kernel News: Monthly chronicle of Linux kernel development.