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)


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  • Jamahl - Thursday, October 1, 2009 - link

    Silicondoc, go see a REAL doc please. Reply
  • 457R4LDR34DKN07 - Thursday, October 1, 2009 - link

    A few points I have about this chip. First it is massive which leads me to believe it is going to be hot and use a lot of power (depending on frequencies). Second it is a one size fits all processor and not specifically a graphics processor. Third is it is going to be difficult to make with decent yields IE expensive and will be hard to scale performance up. I do believe It will be fast due to cache but redesigning cache will be hard for this monolith. Reply
  • silverblue - Thursday, October 1, 2009 - link

    It should take the performance crown back from ATI but I'm worried that it's going to be difficult to scale it down for lesser cards (which is where nVidia will make more of its money anyway).

    When it's out and we can compare its performance as well as price with the 58x0 series, I'll be happier. Choice is never a bad thing. I also don't want nVidia to be too badly hurt by Larrabee so it's in their best interests to get this thing out soon.
  • AnnonymousCoward - Thursday, October 1, 2009 - link

    The Atom is for mobile applications, and Intel is still designing faster desktop chips. The "Atom" of graphics is called "integrated", and it has been around forever. There's no reason to believe that PC games of 2010 won't require faster graphics.

    The fact that nvidia wants to GROW doesn't mean their bread-and-butter business is going away. Every company wants to grow.

    If Fermi's die size is significantly increased by adding stuff that doesn't benefit 3D games, that's a problem, and they should consider 2 different designs for Tesla and gaming. Intel has Xeon chips separate, don't they?

    If digital displays overcome their 60Hz limitation, there will be more incentive for cards to render more than 60fps.

    Lastly, Anand, you have a reoccurring grammar problem of separating two complete sentences with a comma. This is hard to read and annoying. Please either use a semicolon or start a new sentence. Two examples are, Page 8, sentences that begin with "Display resolutions" and "The architecture". Aside from that, excellent article as usual.
  • Ananke - Thursday, October 1, 2009 - link

    Actually, NVidia is great company, as well as AMD is. However, NVidia cards recently tend to be more expensive compared to their counterparts, so WHY somebody would pay more for the same result?

    If and when they bring that Fermi to the market, and if that thing is $200 per card delivered to me, I may consider buying. Most people here don't care if NVidia is capable of building supercomputers. They care if they can buy descent gaming card for less than $200. Very simple economics.
  • SiliconDoc - Thursday, October 1, 2009 - link

    I'm not sure, other than there's another red raver ready on repeat, but if all that you and your "overwhelming number" of fps freaks care about is fps dollar bang, you still don't have your information correct.
    Does ATI have a gaming presets panel, filled with a hundred popular games all configurable with one click of the mouse to get there?
    Somehow, when Derek quickly put up the very, very disappointing new ati CCC shell, it was immediately complained about from all corners, and the worst part was lesser functionality in the same amount of clicks. A drop down mess, instead of a side spread nice bookmarks panel.
    So really, even if you're only all about fps, at basically perhaps a few frames more at 2560x with 4xaa and 16aa on only a few specific games, less equal or below at lower rez, WHY would you settle for that CCC nightmare, or some other mushed up thing like ramming into atitool and manually clicking and typing in everything to get a gaming profile, or endless jacking with rivatuner ?
    Not only that, but then you've got zero PhysX (certainly part of 3d gaming), no ambient occlusion, less GAME support with TWIMTBP dominating the field, and no UNIFIED 190.26 driver, but a speckling hack of various ati versions in order to get the right one to work with your particular ati card ?
    I mean it's nice to make a big fat dream line that everything is equal, but that really is not the case at all. It's not even close.
    I find ragin red roosters come back with "I don't run CCC !" To which of course one must ask "Why not ? Why can't you run your "equal card" panel, why is it - because it sucks ?
    Well it most definitely DOES compared to the NVidia implementation.
    Something usually costs more because, well, we all know why.
  • Divide Overflow - Thursday, October 1, 2009 - link

    Agreed. I'm a bit worried that this monster will cost an arm and a leg and won't scale well into consumer price points. Reply
  • Kingslayer - Thursday, October 1, 2009 - link

    Silicon duck is the greatest fanboy I've ever seen, maybe less annomynity would quiet his rhetoric.">
  • tamalero - Thursday, October 1, 2009 - link

    well that answers everything, when someone has to spam the "catholic", must be a bibblethumper who only spreads a single thing and doesnt believe nor accept any other information, even with confirmed facts. Reply
  • SiliconDoc - Thursday, October 1, 2009 - link

    What makes you think I'm "catholic" ?
    And that's interesting you've thrown out another nutball cleche', anyway.
    How is it that you've determined that a "catholic" doesn't accept "any other 'even confirmed' facts" ? ( I rather doubt you know what Confirmation is, so you don't get a pun point, and that certainly doesn't prove I'm anything but knowledgeable. )
    Or even a "Bible thumper" ?
    Have you ever met a bible thumper?
    Be nice to meet one some day, guess you've been sinnin' yer little lying butt off - you must attract them ! Not sure what proives either, other than it is just as confirmed a fact as you've ever shared.
    I suppose that puts 95% of the world's population in your idiot bucket, since that's low giving 5% to athiests, probably not that many.
    So in your world, you, the athiest, and your less than 5%, are those who know the facts ? LOL
    About what ? LOL
    Now aren't you REALLY talking about, yourself, and all your little lying red ragers here ?
    Let's count the PROOFS you and yours have failed, I'll be generous
    1. Paper launch definition
    2. Not really NVIDIA launch day
    3. 5870 is NOT 10.5" but 11.1" IN FACT, and longer than 285 and 295
    4. GT300 is already cooked and cards are being tested just not by your red rooster master, he's low down on the 2 month plus totem pole
    5. GT300 cores have a good yield
    6. ati cores did/do not have a good yield on 5870
    7. Nvidia is and has been very profitable
    8. ati amd have been losing lots of money, BILLIONS on billions sold BAD BAD losses
    9. ati cores as a general rule and NEARLY ALWAYS have hotter running cores as released, because of their tiny chip that causes greater heat density with the same, and more and even less power useage, this is a physical law of science and cannot be changed by red fan wishes.
    10. NVIDIA has a higher market share 28% than ati who is 3rd and at only 18% or so. Intel actually leads at 50%, but ati is LAST.
    Shall we go on, close minded, ati card thumping red rooster ?
    I mean it's just SPECTACULAR that you can be such a hypocrit.


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