New Features in Linux Kernel 3.9

Ten weeks to the day after the arrival of version 3.8, Linux creator Linus Torvalds on Monday released version 3.9 of the Linux kernel.
“This week has been very quiet, which makes me much more comfortable doing the final 3.9 release, so I guess the last -rc8 ended up working,” wrote Torvalds in the announcement email early Monday. “Because not only aren't there very many commits here, even the ones that made it really are tiny and not pretty obscure and not very interesting.”

Linus Torvalds on Monday released version 3.9 of the Linux kernel.

That's certainly not to say that this new kernel release doesn't include a number of interesting features overall, however – quite the contrary, in fact. Here's a quick look at some of the highlights. 1. SSD Caching
It's always nice to see new features that enable faster performance, and one such example is Linux 3.9's addition of a device mapper target (dm-cache) that enables the use of speedy devices such as solid-state drives (SSDs) as a cache for slower devices such as rotating hard disks.  “Different 'policy' plugins can be used to change the algorithms used to select which blocks are promoted, demoted, cleaned etc.,” explains the changelog on KernelNewbies.org. “It supports writeback and writethrough modes.”
2. Expanded Architecture Support
Broadened support is another change that's pretty much always welcome, and Linux 3.9 actually adds two new architectures to the list of those supported. Specifically, this new release brings the Linux kernel port to the ARC700 processor family (750D and 770D) from Synopsys as well as the Meta ATP (Meta 1) and HTP (Meta 2) processor cores from Imagination. Meta cores can be found in many digital radios, while the ARC700 family is commonly embedded in SoCs in TV set-top boxes and digital media players.
3. Better Power Efficiency
Thanks to the inclusion of the Intel PowerClamp driver, which performs synchronized idle injection across all online CPUs, Linux 3.9 also offers improved power efficiency in terms of performance per watt.
4. Chromebook Support
Particularly useful for Chromebook owners yearning to get their favorite distro up and running on their machine, meanwhile, is that Linux 3.9 adds full support for “all the devices present in the Chrome laptops sold by many companies,” as KernelNewbies puts it.
5. Another Boost for ARM
Linux's support for ARM has improved considerably over the past few releases, and kernel 3.9 brings a key improvement in the form of support for the KVM virtualization system in the ARM architecture port. As KernelNewbies notes, “this brings virtualization capabilities to the Linux ARM ecosystem.”
6. Android Developer Support
Finally, targeting Android developers this time, Linux 3.9 adds support for the “Goldfish” virtualized platform that's part of the Android development environment. Essentially, that means it's now possible to develop for Android with “out-of-the-box” kernels.