The fifth major milestone release in 2013 of the open-source Linux kernel is now available, providing users with improved file system performance. Linux creator Linus Torvalds also used the launch of the new Linux 3.12 kernel as an opportunity to talk about the future of kernel development.

The 3.12 kernel follows the Linux 3.11 release, which debuted in September, providing users with support for the Lustre file system. In Linux 3.12, the ext4 file system, which is used as the default file system in many Linux distributions, is getting a big boost.

The ext4 improvement includes the addition of what Linux developers are referring to as "aggressive extent caching." An "extent" is a common way for modern file systems to store data in a more continuous manner. Ext4's predecessor ext3 used a system in which every 4 kilobytes of data had a piece of metadata pointing to where that data is on the drive. Ext4, in contrast, simply allocates data from a given starting position. Ext4 first debuted as a stable, production-ready file system with the Linux 2.6.28 kernel in 2008.

According to the code commit for the new aggressive extent caching, it is a feature that will decrease memory usage in workloads that are mostly read-only.

Linux 4.0

Torvalds is now beginning to talk openly about the next big number change for Linux with Linux 4.0. Torvalds advanced the Linux kernel from 2.x to 3.x in July of 2011. The move to Linux 3 was not a milestone driven by features; rather it was driven by Torvalds' own desire to keep the release numbers to a manageable number. Prior to the Linux 3.0 release, the last 2.x release was Linux 2.6.39.

"We're getting to release numbers where I have to take off my socks to count that high again," Torvalds wrote in a Linux Kernel Mailing List post. "I'm ok with 3.<low teens>, but I don't want us to get to the kinds of crazy numbers we had in the 2.x series, so at some point we're going to cut over from 3.x to 4.x, just to keep the numbers small and easy to remember."

Seeing as Torvalds is just now releasing the Linux 3.12 kernel, he's not quite yet ready to jump to Linux 4.0, but he will be by Linux 3.19, which will be ready in 2014. While Linux kernels are now time-based rather than feature-based releases, Torvalds wants the Linux 4.0 kernel to have a core focus on stability and bug fixes.

"If we have enough heads-up that people *know* that for one release (and companies/managers know that too) the only patches that get accepted are the kind that fix bugs, maybe people really would have sufficient attention span that it could work," Torvalds wrote.

Sean Michael Kerner is a senior editor at eWEEK and InternetNews.com. Follow him on Twitter @TechJournalist.