After a relatively short development cycle of only nine weeks, Linux 3.10 made its official debut on Sunday.
"So I delayed this by a day, considering whether to do another -rc, but decided that there wasn't enough upside," wrote Linux creator Linus Torvalds in the announcement email on Sunday evening.
The cycle wasn't as quiet as Torvalds would have liked, he explained, and there were more pull requests late in the cycle than he would have wished. Nevertheless, "at some point delaying things doesn't really help things, and just makes the pent up demand for the next merge window worse," he said.
So, the seventh release candidate of this kernel was once again the last one, and Linux 3.10 is now officially here.
Roughly two-thirds of the patches included focus on drivers, Torvalds noted, "while the rest is evenly split between arch updates and 'misc.' No major new subsystems this time around, although there are individual new features."
Ready for a run-down? Here's a quick look at some of the highlights.
1. Timer-Free Multitasking Support
Multitasking capabilities have evolved considerably over the years, but one cost associated with the "preemptive multitasking" that's used in most modern operating systems today is that a timer typically needs to be running continuously in the background. At the same time, "CPUs of laptops and mobile devices require inactivity to enter in low power modes," explains the changelog on KernelNewbies.org. So, because of this timer, those CPUs often can't save as much power as they should. New in Kernel 3.10, however, is support for timer-free multitasking, which should bring better power efficiency.
2. ARM big.LITTLE support
Also notable about Linux 3.10 is that it adds support for the ARM big.LITTLE architecture, an ARM symmetric multiprocessing solution that combines "big" and fast processors with "little" and power-efficient ones. "Power-efficient scheduling is currently a challenge for Linux even on homogeneous architectures; big.LITTLE throws another degree of freedom into the mix," explains Linux kernel developer and LWN.net editor Jonathan Corbet.
In recognition of the growing popularity of solid-state drive storage devices (SSDs) -- something we've also seen addressed in other recent kernel releases -- Linux 3.10 includes Bcache, a filesystem-agnostic technology that allows SSDs to cache other block devices. Created with desktops, servers and high-end storage arrays in mind -- "perhaps even embedded," the changelog notes -- it allows SSDs to act as a cache to slower traditional storage media.
4. A More Space-Efficient Btrfs
New in the Btrfs filesystem, meanwhile, is a new key type for metadata extent references that uses disk space more efficiently. The result is a 30-percent to 35-percent decrease in the size of the extent tree, which means less copy-on-write operations and "larger parts of the extent tree stored in memory, which makes heavy metadata operations go much faster," the changelog explains.
5. Improved Radeon Support
Last but not least, Linux 3.10 includes support for the video accelerators used in AMD's modern Radeon graphic chips. "The Radeon driver in the new Linux kernel now offers interfaces for interacting with the Unified Video Decoder (UVD) on Radeon HD 4000 and later HD graphics cards," explains editor Thorsten Leemhuis on The H.
As always, this is only a small sampling of what's new in Linux 3.10; other enhancements include a variety of drivers, scalability improvements and much more. A thorough summary is available on The H.