Here's some of the changes that have been merged for this next kernel release that make it really great:
- The multi-queue block layer was merged. The multi-queue block layer (blk-mq) provides better disk (SSD) performance and with lower disk latencies by allowing I/O load to now be balanced across multiple CPU cores, supporting multiple hardware queues, etc. The multi-queue block layer can scale much better and developers have reported improvements in the range of 3.5 to 10 times greater IOPS and a 10 to 38x reduction in latency.
- AMD HDMI audio improvements. This includes the AMD hardware on the open-source driver now supporting the reading of ELD audio information, 7.1 channel audio support on capable hardware, and DTS HD-MA and TrueHD audio support. The Radeon HDMI driver is now enabling HDMI audio support by default where as on earlier kernels it required a special kernel command-line switch due to some users experiencing problems.
- AMD has published open-source Hawaii GPU support to allow the Radeon R9 290 series to work on Linux without Catalyst. Besides needing Linux 3.13, you will also need other new code in user-space.
- Radeon DPM is now enabled by default. For users of the open-source Radeon driver there is now dynamic power management being enabled by default rather than being concealed behind a kernel command-line boot-time switch. Dynamic power management allows AMD GPUs to dynamically adjust their clock speeds and voltages based upon load, allowing for lower heat output and energy consumption while idling. This also allows newer, high-end hardware to operate faster as previously the Radeon driver wouldn't up-clock GPUs compared to their boot frequencies. More details are covered in Radeon DPM Is Fantastic For Power Use, Thermal Performance.
- There's now NFTables as the eventual replacement to IPTables. After several years of work, NFTables will be in line for Linux 3.13 and it offers better error reporting, more efficient filtering rules support, a simpler kernel ABI, and will reduce code duplication over IPTables. IPTables isn't yet dead, but this should be a step in the right direction.
- Intel has published open-source Broadwell support for the graphics in the 2014 processors succeeding Haswell. The code comments make us really excited for Intel Broadwell hardware with it said to bring "some of the biggest changes we've seen on the execution and memory management side...equally large and exciting changes for the userspace drivers." Additionally, Broadwell graphics "dwarf any other silicon iteration during my tenure, and certainly can compete with the likes of the gen3->gen4 changes." The Intel Broadwell support will be further refined over future Linux kernel releases and there's also new user-space code required for Broadwell graphics with hardware acceleration on Linux.
- New power management and re-clocking code for the open-source NVIDIA (Nouveau) driver. With the new power management code is now fan management being enabled by default. The re-clocking work does include support for GeForce 400/500 "Fermi" and GeForce 600/700 "Kepler" GPUs, but this re-clocking support isn't yet ready for use or enabled by default. Right now video memory re-clocking isn't working right so there's still a huge performance handicap to Nouveau. Proper re-clocking will allow Nouveau to really compete with NVIDIA's driver.
- There's now an Armada DRM driver in the mainline kernel along with PRIME and Render Nodes improvements to the MSM driver, overall continuing to improve the open-source ARM graphics landscape on Linux. There's also mainline NVIDIA Tegra support for new hardware.
- There's ongoing work with Btrfs performance tuning.
- Samsung's F2FS supports new features as the promising Flash-Friendly File-System.
- In making the Linux power efficiency and performance competitive, there's been a number of changes to ACPI and power management, including more hardware having CPUfreq drivers.
- While part of the power management work, Linux 3.13 introduces a Linux Power-Capping Framework and Run-Time Average Power Liming driver from Intel. The RAPL driver allows limiting power consumption of certain components from exceeding defined thresholds.
- Intel's open-source Direct Rendering Manager driver now supports HDMI Stereo/3D. This support is for the HDMI specification's handling of a standardized stereoscopic 3D display format since version 1.4.
That's 13 interesting items about this next kernel release, but stay tuned for more articles as the 3.13 merge window isn't even over yet! The kernel releases lately have been very exciting in the road to the Linux 4.0 kernel in about one year.