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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  • fic2 - Friday, December 16, 2011 - link


    FX cpus are selling very well: "we can't get enough to meet demand" - i.e. yields are so low that AMD can't produce enough for the 1% of people that want them.
  • ZekkPacus - Friday, December 16, 2011 - link

    At every price point you can get an Intel CPU that will kick the snot out of an FX for the same price, except in VERY specific multi-threaded integer heavy/FP light scenarios.

    Current retail price for the i5-2500k in the UK is £167.40. The FX-8120, which generally appears under the 2500k in bench, costs £179.95 and is as rare as you like. Granted, AM3+ motherboards are much cheaper, but I don't think the cost difference is worth it, especially given we have now gone as far as AM3+ is likely to go and the Piledriver CPU will most likely require a new socket. I personally know from experience that the only two Zambezi parts regularly available in the channel are the FX-4100 and the FX-6100. That's not due to overwhelming demand, that's due to a lack of product being made available by AMD. I find it very telling that not one major OEM is producing desktops based on Zambezi, because they just can't guarantee supply.
  • ZekkPacus - Friday, December 16, 2011 - link

    Infact, a cursory glance reveals that there aren't even any A8-3850 based machines available from HP or Dell. That's the ONE bright spot in AMD's product range right now - an agressively priced quad-core CPU that offers blistering price/performance when compared to an i3, which it's more or less competing against. I'm looking to build an HTPC soon and would've prefered to base it around one of those bad boys, but the 95W TDP and the lack of supply has forced me into Intel's hands again.
  • JonnyDough - Saturday, December 17, 2011 - link

    For an HTPC you could have just used a single core Sempron. LOL
  • vortex222 - Saturday, December 17, 2011 - link

    unless you do transcoding, stream ripping, light big screen gaming, content serving....

    Technically an e350 is a fine htpc core, but in practice such systems are painful to use. Even when surfing to Youtube to watch a video.
  • frozentundra123456 - Saturday, December 17, 2011 - link

    I am becoming somehat more impressed with Llano on the desktop than I was originally, and agree it is the best line that AMD sells.

    However, I wouldnt exactly call the A8-3850 "blistering" in comparison to the i3 2100. Infact I would think that the i3 would offer superior CPU performance in most cases except for very highly theaded scenrios. If you are comparing graphics without a discrete card, then yes, the A8 is superior. But personally, since I do some gaming at moderate settings, I would prefer an i3 with a mid-range discrete card. The A8 IGP is still not quite good enough, and if you add a discrete card, it kind of defeats the purpose of an APU.

    But for HPTC use like you are talking about, Llano might be ideal.
  • ZekkPacus - Wednesday, December 21, 2011 - link

    Was talking purely from a price/performance standpoint - bang for buck, if you like. AMD motherboards are also cheaper than Intel ones whilst retaining the same or better features (c'mon Intel, how long has USB3 been out and it's still not native).
  • Samus - Sunday, December 18, 2011 - link

  • niva - Wednesday, December 21, 2011 - link

    What's the problem, if it gets the job done? If you're not gaming a p4 system might be more than enough for what you need.
  • Roy2001 - Sunday, December 18, 2011 - link

    Nothing can save the BD.

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