ECC Support

AMD's Radeon HD 5870 can detect errors on the memory bus, but it can't correct them. The register file, L1 cache, L2 cache and DRAM all have full ECC support in Fermi. This is one of those Tesla-specific features.

Many Tesla customers won't even talk to NVIDIA about moving their algorithms to GPUs unless NVIDIA can deliver ECC support. The scale of their installations is so large that ECC is absolutely necessary (or at least perceived to be).

Unified 64-bit Memory Addressing

In previous architectures there was a different load instruction depending on the type of memory: local (per thread), shared (per group of threads) or global (per kernel). This created issues with pointers and generally made a mess that programmers had to clean up.

Fermi unifies the address space so that there's only one instruction and the address of the memory is what determines where it's stored. The lowest bits are for local memory, the next set is for shared and then the remainder of the address space is global.

The unified address space is apparently necessary to enable C++ support for NVIDIA GPUs, which Fermi is designed to do.

The other big change to memory addressability is in the size of the address space. G80 and GT200 had a 32-bit address space, but next year NVIDIA expects to see Tesla boards with over 4GB of GDDR5 on board. Fermi now supports 64-bit addresses but the chip can physically address 40-bits of memory, or 1TB. That should be enough for now.

Both the unified address space and 64-bit addressing are almost exclusively for the compute space at this point. Consumer graphics cards won't need more than 4GB of memory for at least another couple of years. These changes were painful for NVIDIA to implement, and ultimately contributed to Fermi's delay, but necessary in NVIDIA's eyes.

New ISA Changes Enable DX11, OpenCL and C++, Visual Studio Support

Now this is cool. NVIDIA is announcing Nexus (no, not the thing from Star Trek Generations) a visual studio plugin that enables hardware debugging for CUDA code in visual studio. You can treat the GPU like a CPU, step into functions, look at the state of the GPU all in visual studio with Nexus. This is a huge step forward for CUDA developers.

Nexus running in Visual Studio on a CUDA GPU

Simply enabling DX11 support is a big enough change for a GPU - AMD had to go through that with RV870. Fermi implements a wide set of changes to its ISA, primarily designed at enabling C++ support. Virtual functions, new/delete, try/catch are all parts of C++ and enabled on Fermi.

Efficiency Gets Another Boon: Parallel Kernel Support The RV770 Lesson (or The GT200 Story)


View All Comments

  • ioannis - Friday, October 2, 2009 - link

    Although the Star Trek TNG reference is ok, 'Nexus' should have been accompanied by a Blade Runner reference instead, Nexus-6 :)
  • - Friday, October 2, 2009 - link

    You are all talking too much about technologies. Who cares about this? DX11 from ATI is already available in Japan and they are selling like sex dolls. And why didnt NVDIA provided any benchmarks? Perhaps the drivers aren ready or Nvidia doesnt even know at what clockspeed this monster can run without exhausting your pcs power supply. Fermi is not here yet, it is a concept but not a product. ATI will cash in and Nvidia can only look. And when the Fermi-Monster will finally arrive, ATI will enroll with 5890 and X2 in the luxury class and some other products in the 100 Dollar class. Nvidia will always be a few months late and ATI will get the business. It is that easy. Who wants all this Cuda stuff? Some number crunching in the science field, ok. But if it were for physix an add-on board would do. But in reality there was never any run for physix. Why should this boom come now? I think Nvdia bet on the wrong card and they will suffer heavily for this wrong decision. They had better bought VIA or its CPU-division instead of Physix. Physix is no standard architecture and never will. In contrast, ATI is doing just what gamers want and this is were the money is. Were are the Gaming-benchmarks for FERMI? Nvidia is over! Reply
  • - Friday, October 2, 2009 - link

    With all this Cuda and Physix stuff Nvidia will have 20-30% more power consumption at any pricepoint and up to 50% higher production costs because of their much bigger die size. ATI will lower the price whenever necessary in order to beat Nvidia in the market place! And when will Nvida arrive? Yesterday we didnt see even a paperlaunch! It was the announcement of a paperlaunch maybe in late december but the cards wont be available until late q12010 I guess. They are so much out of the business but most people do not realise this. Reply
  • Ahmed0 - Friday, October 2, 2009 - link

    I know for sure SD is from Illinois (his online profiles which are related to his rants [which in turn are related to each other] point to it).

    So, Im going to go out on a limb here and suggest that SiliconDoc was/is this guy:">

    A little googling might (or might not) support the fact that he is a loony. Just type " silicondoc" and youll find he has quite a reputation there (different site but seems to be the same profile, "handwriting" and same bike)

    And that MIGHT lead us to the fact that he MIGHT actually be (currently) 45 and not a young raging teenage nerd called Brian.

    Of course... this is just some fun guesswork I did (its all just oh so entertaining).
  • Ahmed0 - Friday, October 2, 2009 - link

    Well... either that or all users called SiliconDoc are arsholes. Reply
  • k1ckass - Friday, October 2, 2009 - link

    I guess silicondoc would eat **** if nvidia says that it tastes good, LOL.

    btw, fermi cards shown appears to be fake...">

    and btw, I use an nvidia gtx, propable would get an hd5870 next week because of all this crap nvidia throws at its consumers.
  • Pastuch - Friday, October 2, 2009 - link

    Below is an email I got from Anand. Thanks so much for this wonderful site.

    Thank you for your email. SiliconDoc has been banned and we're accelerating the rollout of our new comments rating/reporting system as a result of him and a few other bad apples lately.


  • tamalero - Saturday, October 3, 2009 - link

    about time, was getting boring with the constant "bubba, red roosters, morons..etc.." Reply
  • sigmatau - Friday, October 2, 2009 - link

    SiliconDoc getting banned.... PRICELESS.
  • PorscheRacer - Friday, October 2, 2009 - link

    So it's safe now to post again? Much thanks has to go to Anand to cleaning up the virus that has infected these comments. I mean, it's new tech. Aren't we free to postulate about what we think is going on, discuss our thoughts and feelings without fear of some person trolling us down till we can't breathe? It feels better in here now, so thanks again. Reply

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