Efficiency Gets Another Boon: Parallel Kernel Support

In GPU programming, a kernel is the function or small program running across the GPU hardware. Kernels are parallel in nature and perform the same task(s) on a very large dataset.

Typically, companies like NVIDIA don't disclose their hardware limitations until a developer bumps into one of them. In GT200/G80, the entire chip could only be working on one kernel at a time.

When dealing with graphics this isn't usually a problem. There are millions of pixels to render. The problem is wider than the machine. But as you start to do more general purpose computing, not all kernels are going to be wide enough to fill the entire machine. If a single kernel couldn't fill every SM with threads/instructions, then those SMs just went idle. That's bad.


GT200 (left) vs. Fermi (right)

Fermi, once again, fixes this. Fermi's global dispatch logic can now issue multiple kernels in parallel to the entire system. At more than twice the size of GT200, the likelihood of idle SMs went up tremendously. NVIDIA needs to be able to dispatch multiple kernels in parallel to keep Fermi fed.

Application switch time (moving between GPU and CUDA mode) is also much faster on Fermi. NVIDIA says the transition is now 10x faster than GT200, and fast enough to be performed multiple times within a single frame. This is very important for implementing more elaborate GPU accelerated physics (or PhysX, great ;)…).

The connections to the outside world have also been improved. Fermi now supports parallel transfers to/from the CPU. Previously CPU->GPU and GPU->CPU transfers had to happen serially.

A More Efficient Architecture ECC, Unified 64-bit Addressing and New ISA
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  • 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.
  • 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.
  • Kingslayer - Thursday, October 1, 2009 - link

    Silicon duck is the greatest fanboy I've ever seen, maybe less annomynity would quiet his rhetoric.

    http://www.automotiveforums.com/vbulletin/member.p...">http://www.automotiveforums.com/vbulletin/member.p...
  • 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.
  • 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.

  • tamalero - Friday, October 2, 2009 - link

    a.-Since when the yields of the 5870 are lower than the GT300?
    they use the same tech and since the 5870 is less complex and smaller core, it will obviusly have HIGHER YIELDS. (also where are your sources, I want facts not your imaginary friend who tells you stuff)
    2.-Nvidia wasnt profiteable last year when they got caught shipping defective chipsets and forced by ATI to lower the prices of the GT200 series.
    3.- only Nvidia said "everyhing is OK" while demostrating no working silicon, thats not the way to show that the yields are "OK".
    4.- only the AMD division is lossing money, ATI is earning and will for sure earn a lot more now that the 58XX series are selling like hot cakes.
    5.- 50% if you count the INTEGRATED market, wich is not the focus of ATI, ATI and NVidia are mostly focused on discrete graphics.
    intel as 0% of the discrete market.
    and actually Nvidia would be the one to dissapear first, as they dont hae exclusivity for their SLIs and Corei7 corei5 chipsets.
    while ATI can with no problem produce stuff for their AMD mobos.


    and dude, I might be from another country, but at least Im not trying to spit insults every second unlike you, specially when proven wrong with facts.
    please, do the world a favor and get your medicine.

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