Linux’s 2011 milestones were more than a change in version number. The year brought major work in memory management, scheduling, locking, and Xen virtualization, while Linux moved from the 2.6 series to 3.0 to mark its 20th anniversary. The release sequence ran from Linux 2.6.37 on January 4 to Linux 3.1 on October 24.
Linux kernel releases in 2011, in order
| Release | Date | Why it mattered |
|---|---|---|
| Linux 2.6.37 | January 4, 2011 | First upstream kernel able to boot as a Xen Dom0 host, though backend-driver support was still limited. Xen Project |
| Linux 2.6.38 | March 14, 2011 | Advanced Transparent Huge Pages and automatic process grouping; also included B.A.T.M.A.N. mesh networking and pstore. Kernel.org release history |
| Linux 2.6.39 | May 18, 2011 | Removed the Big Kernel Lock and added UniCore-32 support. State of the Kernel presentation |
| Linux 3.0 | July 21, 2011 | Marked Linux’s 20th anniversary with a numbering reset, not a wholesale technical break from 2.6.39. Linux Foundation |
| Linux 3.1 | October 24, 2011 | First release after 3.0, issued as the Kernel Summit began. LWN.net |
The dates above identify these major mainline releases, not every point release, distribution backport, or individual change made during the year.
What changed in Linux 2.6.38?
Memory management: Transparent Huge Pages
Transparent Huge Pages (THP) aimed to reduce page-management overhead for workloads using large memory regions. By handling memory in larger units where appropriate, the feature sought to make large-memory workloads more efficient without requiring applications to manage huge pages directly. The feature was one of several scalability-focused changes highlighted for 2.6.38. State of the Kernel presentation
Scheduling: automatic process grouping
Automatic process grouping, often called the “wonder patch,” grouped processes in the same session or terminal. The goal was improved fairness and responsiveness: a group doing substantial work should not let one process dominate scheduling simply because it spawned many processes.
The Tool Desk
Outbyte Driver Updater FREEFix the driver behind crashes, sound loss and screen glitchesFind Drivers →Outbyte PC Repair FREERepair Windows errors before they cause bigger problemsFix Now →#1 Best Overall
Networking and crash-data preservation
Linux 2.6.38 added B.A.T.M.A.N. mesh networking, which supports routing across a mesh of participating nodes. It also included pstore, a mechanism for preserving crash data across a reboot so it can be examined afterward. Transcendent Memory work appeared in staging, the kernel area used for code not yet ready for full mainline status. State of the Kernel presentation
Why Linux 2.6.39’s Big Kernel Lock removal mattered
The Big Kernel Lock (BKL) was a broad serialization mechanism: code holding it could prevent other kernel work from proceeding concurrently. Its removal in 2.6.39 marked a significant step in a longer effort to reduce global bottlenecks and improve concurrency. That milestone should not be read as a claim that every kernel operation became fully parallel; it records the removal of this particular major locking mechanism. The release also included UniCore-32 and Transcendent Memory support. State of the Kernel presentation
Why Linux moved from 2.6.39 to 3.0
Linux 3.0 was released on July 21, 2011, for the project’s 20th anniversary. The jump was primarily a version-numbering reset, not a declaration of a new kernel architecture or a broad compatibility break. The Linux Foundation quoted Linus Torvalds describing the change as “simply a way to drop an inconvenient numbering system in honor of twenty years of Linux.” Torvalds also said the 3.0 merge window had been calmer than most. Linux Foundation’s 2011 review Kernel.org
Linux continued its established time-based mainline cadence after the renumbering: 3.1 followed on October 24, as the Kernel Summit began. The first digit changing did not, by itself, mean that software users should expect a wholesale technical rewrite. LWN.net
PC Slower Than It Used to Be?
A free scan shows the junk files, broken settings and background clutter dragging Windows down - then fixes them in one click.Free scan · Windows 10 & 11Outdated Drivers Are Slowing You Down
One free scan finds every outdated or missing driver and matches the right update for your exact hardware.Free scan · exact hardware matchRank #3
How Xen host support advanced during 2011
Xen support illustrates why a version milestone can represent a progression rather than a single on/off event. Linux 2.6.37 was the first upstream kernel reported to boot as a Xen Dom0, or host domain, although backend-driver limitations remained. By Linux 3.0, the mainline kernel had the needed Dom0 and DomU support, enabling Linux to act as a Xen host using upstream code rather than relying on the same extent of out-of-tree patching. Xen Project Linux Foundation
Other upstream and architecture milestones
The Linux Foundation’s year-end review also identified several changes beyond the headline releases:
Rank #4
- Used Book in Good Condition
- OpenRISC support: an additional architecture milestone.
- SMEP: Supervisor Mode Execution Protection, a processor security feature supported by the kernel.
- User namespaces and IP Sets: kernel capabilities relevant to isolation and network administration.
- Ext4 write barriers: work related to ordering writes for filesystem reliability.
- ARM upstreaming: continued effort to reconcile and bring into mainline development that had been fragmented across vendor trees.
These examples show that 2011’s story was not limited to a handful of release headlines: architecture support, security, filesystem behavior, and integration work were progressing alongside them. Linux Foundation’s 2011 review
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.A fast release cadence built on distributed contributions
Kernel.org’s development documentation describes a rolling, time-based process: mainline releases arrive roughly every two or three months, with a merge window followed by release candidates. The documentation says more than 9,500 patches went into Linux 2.6.38, while 112—about 1.3%—were selected directly by Linus Torvalds. Those figures, as stated in the current kernel development documentation, illustrate the maintainer-led and distributed nature of kernel development; they are not a complete accounting of all development activity in 2011. Kernel.org development process
Why consumer-device vendors pursued longer support
The Linux Foundation identified the Long Term Support Initiative (LTSI) as another important 2011 development. A workgroup that included Hitachi, LG Electronics, NEC, Panasonic, Sony, Toshiba, and Samsung sought a shared consumer-device kernel tree supported for two to three years—roughly the typical lifespan of consumer electronics, according to the Foundation. The initiative addressed a different problem from mainline’s rapid release rhythm: device makers often need a more stable maintenance horizon than a new mainline release every few months provides. Linux Foundation’s 2011 review
What the 2011 milestones add up to
The most consequential pattern was gradual modernization, not a dramatic reset. Linux 2.6.38 brought memory and scheduling changes alongside networking and crash-data tools; 2.6.39 removed the BKL; and Xen host support matured across 2.6.37 and 3.0. The 3.0 label commemorated 20 years of Linux, while LTSI reflected a parallel effort to serve hardware vendors that needed longer-lived kernels. These milestones capture major themes, rather than an exhaustive account of every 2011 kernel change.
Quick Recap
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
