The launch of Bulldozer in October wasn't exactly a success for AMD. In our review, Anand ended up recommending the Intel i5-2500K over AMD FX-8150. One of the reasons behind the poor performance of Bulldozer is its unique design: each Bulldozer module consists of two integer and one floating point core. Todays operating systems don't know how to optimally schedule threads for this design and as a result, the full potential of Bulldozer has not been achieved. Microsoft has released a hotfix for Windows 7 and Server 2008 R2 that should increase the performance of Bulldozer.

Let's look at the problem to see what happened and how the hotfix helps address it. Before the update, Windows didn't know how to ideally schedule threads on Bulldozer. Essentially, it didn't know when it was good to place threads on single module versus multiple modules.

The picture above explains this pretty well. Before the update, Windows more or less randomly placed the threads which meant many modules were unnecessarily active at the same time. This capped the maximum Turbo speeds because those can only be achieved when some of the modules are inactive (power gated).

VR-Zone is claiming that Windows sees one Bulldozer module as a single multi-threaded core, similar to an Intel Hyper-Threading core. Basically, your 8-core FX-8150 is seen as a quad-core, 8-thread CPU—just like Intel's i7-2600K for instance. This goes against AMD's design and marketing because Bulldozer is closer to an 8-core CPU.

We have not yet tested Bulldozer with the hotfix, but don't expect miracles as Microsoft is suggesting a 2-7% increase. Better scheduling for the Bulldozer CPUs will improve performance a bit, but not enough to close the gap in many scenarios. Windows 8 already has the new thread scheduler, and according to AMD's own and third party tests the performance increase is up to around 10%, but Bulldozer needs a lot more than 10% to surpass Sandy Bridge.

Update: VR-Zone reports (and we can confirm) that the download link for the hotfix is no longer functional. There were apparently unexpected performance drops in some cases after applying the hotfix and Microsoft is investigating the issues. Modifying the scheduler in Windows is not something to be done lightly, as it changes a core element of the OS, so more testing and validation for such updates is always a good idea.

Update 2: Apparently there is a second part to the hotfix that was not pushed live, and this hotfix was pushed live prematurely.

Source: Microsoft

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  • LancerVI - Friday, December 16, 2011 - link

    Hey, 10% may not catch it up, but a 10% bump is pretty damn good!

    That being said, I'm still waiting to replace my I7 920 C0 with something. It's probably going to be Ivy Bridge.
  • goldenatom - Friday, December 16, 2011 - link

    Same here, the old 920 is feeling a bit long in the tooth, pretty disappointed by the Ivy Bridge delay....not to mention the limited (and dang expensive) cpu releases for x58 over time...
  • KingofL337 - Friday, December 16, 2011 - link

    I'm still Rocking a Q6600 @ 3.5GHz and haven't found a reason to upgrade.
  • MonkeyPaw - Friday, December 16, 2011 - link

    I just grabbed a Phenom II X4 at 3.3ghz. Not cutting edge anymore, but considering I was moving from a 1.3ghz single core, it's significantly better. :)
  • knedle - Friday, December 16, 2011 - link

    I gave up on my Q6600 and gave it to my brother, he never complained to me about it's performance, so I think it's still pretty good CPU.
    As for me, I moved to Sandy Bridge - something more energy efficient, to minimize electricity bills. ;)
  • dj christian - Saturday, December 17, 2011 - link

    Agreed! See no reason for me upgrading my old trustworthy Q6600 until Ivy Bridge comes out. Will do good for both perfomance, powerdraw and requiring less powerfull fan which will do good for noise.
  • CK804 - Friday, December 16, 2011 - link

    I'm still running a Q6700 at stock speeds on a 975X board. The only reason for me to upgrade would be to lower power consumption and noise.
  • claytontullos - Saturday, December 17, 2011 - link

    I've got a 920 D0 - No reason to upgrade.

    I've got it clocked at 3.6ghz.
  • Samus - Sunday, December 18, 2011 - link

    ditto, i have my 920 d0 clocked at 3.96 at 1.325v, completely cool and stable, no reason to upgrade, especially with 12gb of triple channel
  • augiem - Sunday, December 18, 2011 - link

    Same here. (Can't remember the stepping.) @ 3.6 + 12GB mem, I don't see anything out there on the market worth spending hundreds of dollars on for an upgrade. Sure, you may get a 4.0 clock and 10% better performance per clock with SB, but it's just not significant in real-world use. I'm really suprised this build has lasted me 2.5 years already with no signs of feeling at all weak with all the 3D, video editing, photoshop, games, etc. stuff I do. I'm used to a 1.5 year upgrade cycle, but there's just no reason to upgrade. I guess processors just haven't been improving at the break-neck pace of the past.

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