Linux 3.9 kernel release offers SSD caching and server performance improvements

Linux 3.9 kernel release offers SSD caching and server performance improvements

Summary: The Linux 3.9 kernel brings with it an SSD caching, improved performance for multi-threaded network server applications and a host of other features.

TOPICS: Open Source, Linux

The latest version of the Linux kernel has been released – bringing with it support for SSD caching and a performance boost for some server workloads.

The 3.9 release, made available by Linus Torvalds on Sunday, offers various performance enhancements, new features and additional driver support.

SSD caching

SSDs or other storage devices will be able to be used as a cache for a hard drive, potentially speeding up data writes and reads. The ability to use SSDs as a cache comes courtesy of changes to the Device Mapper, which now includes a cache target called "dm-cache".

Server performance

Performance of multi-threaded network server applications running on multi-core systems should be improved. The improvement stems from the TCP and UDP sockets supporting a SO_REUSEPORT socket option that allows multiple sockets on the same host to bind to the same port.

Power consumption

The kernel will also support a "lightweight suspend" mode that is reported to allow some phones and tablets to consume almost as little power as when they are put into the deeper and less responsive suspend-to-RAM state.

The inclusion of Intel's PowerClamp driver will also allow the maximum power consumption of Intel processors to be throttled to limit a system's power consumption.

Raid support

The B-tree file system (Btrfs) has new Redundant Array of Inexpensive Disc (RAID) support, including experimental native support for RAID 5, block-level striping with distributed parity, and RAID 6, block-level striping with double distributed parity, in addition to Raid 0 and Raid 1 support. Embedding RAID capabilities within the file system should also make it simpler to manage the RAID array and restore data in the event of a failure.


Integrated into the 3.9 kernel are drivers for VMware's Virtual Machine Communication Interface (VMCI), which reduces the overhead in communication between virtual machines and their host.

The KVM hypervisor in the kernel will support the virtualisation features of the processors based on Arm's Cortex A15 core, allowing KVM to work on Arm cores.

Drivers for the Xen hypervisor in the kernel will also allow hotplugging of processors and memory components, allowing them to be swapped while the host system is running. The kernel's code for Microsoft's Hyper-V hypervisor also now supports the improved interrupt model introduced with Windows 8.

Graphics drivers

Support for AMD's forthcoming Fusion APUs based on its Richland architecture has been added. New AMD graphics chips are also supported, with the kernel's Radeon graphic driver now supporting the Oland graphics chips used on Radeon HD 8500 and 8600 cards. 

The graphics driver for the integrated GPU in Intel's upcoming Haswell processors has been tweaked to allow the graphics core to use less power when a single display pipe is used in the Embedded DisplayPort. Texas Instruments OMAP processor graphic drivers will also offer improved power management features and support OMAP5.

The Nouveau driver for Nvidia cards adds experimental automatic and manual fan controls for the NV40 and NV50 GPUs used on the GeForce series 6xxx to 9xxx cards. The kernel also now offers Nvidia Tegra 4 support. 

Changes to the locking mechanism used by graphics drivers should help prevent displays from temporarily freezing when the system checks available monitors.

Meanwhile updated code for compressing and decompressing LZO should allow for faster processing by CPUs.


The kernel includes a driver for Intel's series 7000 wi-fi components. The Ethernet subsystem features a driver for the AX88179 component used in a variety of USB 3.0 gigabit LAN hardware. Support for the Multiple Registration Protocol that was specified in IEEE 802.1Q-2011 has also been added to the network stack.

The driver code used to configure HD audio codecs is reported to have been made leaner and more robust. Support for Creative's CA0132 sound chip used in various motherboards has also been added.

Meanwhile the perf performance analysis tool now includes a test routine for measuring the memory performance of Non-Uniform Memory Access systems, with the kernel developers also shrinking some of the tracing data structures to improve performance.

Topics: Open Source, Linux


Nick Heath is chief reporter for TechRepublic UK. He writes about the technology that IT-decision makers need to know about, and the latest happenings in the European tech scene.

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  • Linux 3.9 kernel release offers SSD caching and server performance improvem

    Get those compilers ready boys, its going to be a while. Download, compile, configure, repeat. The 4 steps of linux. So glad I choose not to run linux and no don't have to continuously mess around with my PC. It just works without linux.
    • Oh Really ?

      Lovie, I just tell Open Suse to update and it's done ... Kinda like patch Tuesdays, but without breaking anything ...
      • More boring LD FUD!

        He is a laugh and only a laugh.
      • Update kernel without rebooting?

        I'm genuinely interested, can Open Suse update the kernel without rebooting? I'd thought only Ksplice (which is now owned by Oracle) allowed this.
        • Re: Update kernel without rebooting?

          Last time I did an OpenSuSE install, it didn't even need to go through a full boot to switch from the installation CD to the newly-installed system.
          • Re: Update kernel without rebooting?

            Sure, but updating the kernel without rebooting is a whole different beast.
      • I cannot remember the last

        Time patch tuesday broke something on any of my server or desktop systems. On the other hand, kernel updates on any flavour of Linux, in combination with certain software (such as Asterisk for instance) are a sure way to break things.
        • I guess you missed the ZDnet article

          "Microsoft pulls Patch Tuesday security fix"

          From just 2 weeks ago. Bricked who knows how many Windows systems.
          • Well

            You obviously missed the part where I go on about my servers and clients none of which were bricked by the recalled update.

            Although several of them must have it applied considering I run quite a few hundred Windows 7 machines and quite a few hundred Server 2008 R2 systems.
          • I din't miss the times that Mint broke...

            Several times, and had to boot windows to then learn how to fix what the updates broke. I too have never had any catastrophic issues with Windows updates. Yes, they have broken stuff, but I could at least boot into the desktop and fix it, not have to boot into a different machine to learn how to fix it.
        • I can

          Currently have a system with a very borked graphics driver after a "patch tuesday". It's not a "show stopper" but the system is 'degraded'.
    • The only criticism you ever have of linux is a lie.

      please stop these waste of our time posts.
      • The inserted spam messages are more worthwhile reading.

      • He thinks he's being funny

        This is his bit. There are a few here on ZD like this. Personally, I think it's a waste of time. We should all just ignore them.
        • Sigh ....

          Unfortunately you are right. Oh how I miss the days of William Patel AKA Mike Cox ...
          The WERE and had to be the BEST TALK BACKS on ZdNet
    • What do you use?

      It's not obviously windows... if it is you must teach me how to get rid of anti-virus, slow performance with time, updates that brick my machine, ...
      • I guess

        you aren't using Windows as well, certainly not the NT flavour of Windows, as none of the things you describe have bothered me, absolutely none of them.
        • I am

          And yes I've antivirus - when it's outdated I even get a warning message about being in danger.
          Yes performance goes down with time, after a clean install, take word as example, it can start in about 1 or 2 seconds - with time, several seconds.
          Recently a bad update bricked a few Windows machines - one example.
          Not saying others are better or worse, but windows is far from perfect.
          As for you, well I guess you are just a lucky person, because the problems I told about are famous.
    • Please

      Can people have mature adult conversation or does the word comments mean leave you maturity behind .

      I have installed Ubuntu LAMPS with webadmin and MyPHPAdmin on a Pentium 4 system twice . No compiling is needed. By the way I am a Windows 8 user and like for the most part. If you want to disagree with the article do so objectivity and logically. Tolling is for Kids.
      • .

        You must be new to ZDNet.