Following nearly three months of development, Linus Torvalds has released version 2.6.32 of the Linux kernel, which brings a number of improvements to the open source operating systems' graphics, virtualization and power management capabilities, as well as boosting overall performance.
In an announcement to the kernel mailing list, Torvalds said the release “feels long overdue” but it has been less than three months since 2.6.31.
Following eight release candidates, Torvalds said the "big feature" changes in 2.6.32 since 31, is with the Btrfs file system and the block layer writeback system.
“Other rather noticeable changes are in Intel and Radeon [drivers] and in drivers all over the place,” Torvalds wrote.
The recent inclusion of GEM (2.6.28) and KMS (2.6.29) in past kernel releases is now allowing significant advancements in Linux’s graphics support.
The Radeon driver for AMD (formerly ATI) r600/r700 3D graphics cards has KMS support and is based on the hardware specs that AMD has published.
The new drivers include 3D support, possibly making them the most advanced open source graphics card drivers.
Intel graphics drivers have also received enhancements; however, NVidia cards still require the binary Linux driver.
New VGA arbitration code solves problems relating to concurrent access for multiple independent processes to the VGA resources of multiple cards.
Linux’s new advanced file system, Btrfs, has also been updated to improve performance across workloads.
The introduction of Kernel Samepage Merging (or memory deduplication) is also designed to help improve performance of virtual machines. The KSM kernel daemon, ksmd, scans areas of user memory looking for pages of identical content which can be replaced by a single write-protected page, resulting in a dramatic decrease in memory usage in virtual environments.
Red Hat found that by using KSM, KVM (kernel-based virtual machine) can run as many as 52 Windows XP VMs with 1GB of memory each on a server with just 16GB of RAM.
KSM works transparently to user applications and can provide memory savings to existing production systems. KSM was originally developed for use with KVM, but it can be also used with any other virtualization system or in non-virtualization workloads.
General KVM virtualization improvements include: I/O performance improvements, syscall/sysenter emulation for cross-vendor migration, better SMP performance and support for 1GB pages.
For power management, there is new code for ACPI 4.0 support making Linux the first platform to support the specification.
Suspension of the operating system for energy-saving modes also received updates.
For a detailed list of changes made for the 2.6.32 release, see the Kernel Newbies 2.6.32 page.