A new version of the Linux kernel, 2.6.34, has been released by Linus Torvalds featuring two new file systems and a number of updates to virtualisation and device driver code.
Btrfs, the next-generation file system for Linux, has also received a number of updates like better snapshot control, a new “btrfs” user command, a new interface for incremental backups.
The ability to compress a single file on demand and defrag a set range of bytes in the file has been added to the defragmentation code in Btrfs.
Kernel 2.6.34 comes nearly three months after the previous version, and by Torvalds’ own admission “nothing really stands out”.
“Nothing very interesting here, which is just how I like it,” Torvalds wrote in the release announcement to the Linux kernel mailing list.
“Various random fixes all over, nothing really stands out. Pretty much all of it is one- or few-liners, I think the biggest patch in the last week was fixing some semantics for the new SR-IOV VF netlink interface. And even that wasn't a big patch by any means.”
Virtualisation features enhancements include a new “vhost net” kernel-level backend for near-native KVM network performance.
This driver reduces virtualisation overhead and can reduce latency by a factor of five and improve bandwidth to almost-native performance. Existing “virtio net” code is used in guests without modification.
A VMware ballon driver has made it into 2.6.34 which allows the hypervisor to dynamically limit the amount of memory available to the guest. This driver will only activate if the host hypervisor is VMware.
“So 2.6.34 is out, and the merge window is thus officially open,” Torvalds wrote. “As usual, I probably won't do any real pulls for a day or two, in the (probably futile) hope that we'll have more people running plain 2.6.34 for a while. Go forth and test.”
The many driver changes include updates for Intel, nVidia (Nouveau) and Radeon graphics, storage, networking, USB, sound and video.
Architecture developments include a lot of activity around ARM, which is popular in mobile devices.
For a detailed summary of the changes for the 2.6.34 release, see the Kernelnewbies.org page.