The group scheduling improvements are of course, very well known already via our article with videos entitled The ~200 Line Linux Kernel Patch That Does Wonders. Each of the two videos showing off this feature now in the mainline kernel earned over 100,000 views each on YouTube. The improved group scheduling really improves the overall desktop experience if running intensive tasks from the terminal (i.e. a multi-threaded application or GCC with multiple jobs) while still having a responsive system to do other things like surf the web or watch movies.
The RCU-based path name lookup is Torvalds' other favorite feature. "The RCU-based name lookup is at the other end of the spectrum - the absolute anti-gimmick. It's some seriously good stuff, and gets rid of the last main global lock that really tends to hurt some kernel loads. The dentry lock is no longer a big serializing issue. What's really nice about it is that it actually improves performance a lot even for single-threaded loads (on an SMP kernel), because it gets rid of some of the most expensive parts of path component lookup, which was the d_lock on every component lookup. So I'm seeing improvements of 30-50%
on some seriously pathname-lookup intensive loads."
You can bet I am getting ready to benchmark this kernel release with OpenBenchmarking.org and Phoronix Test Suite 3.0 "Iveland" code.
There's many big DRM improvements for the open-source graphics drivers in this forthcoming kernel.
Also in the Linux 2.6.38 kernel is initial Nouveau Fermi acceleration support so that the DRM bits are in place for NVIDIA GeForce 400/500 series graphics cards can play with the open-source Nouveau driver for 2D/X-Video and 3D (Gallium3D) acceleration.
On the AMD side, the open-source Fusion support has landed along with the support for the Radeon HD 6000 series graphics cards.
One of my favorite features about the Linux 2.6.38 kernel are the ATI KMS driver improvements. Besides bringing support for Fusion and Northern Islands to the open-source driver, the 2.6.38 kernel has KMS page-flipping support, which delivers major performance improvements. (I have more Radeon 2.6.38 benchmarks on the way in the coming days.)
Last but not least, there's new drivers, ARM architecture updates, and lots of other improvements to love about the Linux 2.6.38 kernel. This is one of the most exciting kernel releases I've been looking forward to in a while.
You can read the Torvalds' 2.6.38-rc1 kernel release announcement at LKML.org.