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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  • rennya - Friday, October 2, 2009 - link

    Go ask the administrator to check my IP and they can verify that my IP comes from a SE Asia country. Are you accusing me of lying for claiming that I come from a nirvana where 5870 GPU is plentiful?

    Is that all you can do?

    Fact - 5870 is not paper launch. You cannot even deny this.

    Ah, BTW, English in SE Asia is the same as the ones used in America and Europe.
  • Totally - Friday, October 2, 2009 - link

    Seriously, what are you on? It has to be some good stuff. I want some.

    I like how you go on and on spouting nonsense about how GT300 has 50% more theoretical bandwith, but without clock speeds there is no way to gauge how much of it will be saturated. In plain speak: Without hard numbers BANDWIDTH ALONE MEANS NOTHING. Sure nvidia has tons of road but we have no idea what they are going to drive on it.

    About the 5870 being a paper launch, my best friend had his since the 30th. Day the 5850 launched, took a look over at newegg at 7 in the evening they where there available to order. And still you can order/go to the store and purchase either right now!!! That's not a paper launch. Last time I checked a paper launch is when a product goes live and it's unavailable for over a month.
  • lyeoh - Friday, October 2, 2009 - link

    Doesn't look like good stuff to me. You'd probably get brain damage or worse.

    Should be banned in most countries.
  • SiliconDoc - Wednesday, September 30, 2009 - link

    When anand posts the GD bit width and transistor count, and mem, then CLAIMS bandwith is NOT DOUBLE, it is CLEAR the very simple calculation you 3rd graders don't know is AVAILABLE.
    ---
    IT'S 240 GB !
    4800x384/8 !

    duhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh

    It's not FUD, it's just you people are so ignorant it's EASY to have the wool pulled over your eyes.
  • Lightnix - Wednesday, September 30, 2009 - link

    4800mHz x 384 / 8 = 230400mB/s = 230.4GB/s

    Or 50% faster than 153GB/s - still a big gap but clearly not even nearly double.

    It's not FUD, it's just you trolls are so bad at maths you can't even use a calculator to do basic arithmetic with it's EASY to have the wool pulled over your eyes.
  • SiliconDoc - Wednesday, September 30, 2009 - link

    The author claimed not double the former GT200, sir.
    In the 5870 review just the other day, the 5870 had a disappointing 153+ bandwith, vs the 115 of the 4780 or 124 of the 4890.
    --
    So you can see with the 5870 it went up by not much.
    --
    In this review, the former GT200 referred to has a 112, 127, 141, or 159 bandwith, as compared to the MYSTERY # 240 for the GT300.
    So the author claims in back reference to the ati card the nvidia card "also fails" to double it's predecesor.
    --
    I have a problem with that - since this new GT300 is gonig to be 240 bandwith, nearly 100 GB/sec more than the card the author holds up higher and gioves a massive break to, the one not being reviewed, the ati 5870.
    --
    It's bias, period. The author could fairly have mentioned how it will be far ahead of it's competition, and be much higher, as it's predecessor nvidia card was also much higher.
    Instead, we get the cryptic BS that winds up praising ati instead of pointing out the massive LEAD this new GT300 will have in the bandiwth area.
    I hope you can understand, but if you cannot, it's no wonder the author does such a thing, as it appears he can snowball plenty with it.
  • UNCjigga - Thursday, October 1, 2009 - link

    STFU you stupid moron. There's no "bias". The 5870 has a full, in-depth, separate review with full benchmarks. The author didn't do direct comparisons because THERE IS NO CARD TO COMPARE IT WITH TODAY. FERMI ONLY EXISTS ON PAPER--the mere existence of engineering samples doesn't help this review. The author even indicated he wished he had more info to share but that's all Nvidia allowed. How about we wait until a GT300 ships before we start making final judgements, ok?
  • SiliconDoc - Thursday, October 1, 2009 - link

    Good job ignoramus.

    http://www.fudzilla.com/content/view/15762/1">http://www.fudzilla.com/content/view/15762/1

    Oh, look at that, you're 100% INCORRECT.

    Another loser idiot with insults and NOTHING ELSE but the sheepled parrot mind that was slammed into stupidity by the author of this piece.

    Great job doofu.
  • ufon68 - Thursday, October 1, 2009 - link

    Wow, you must be the biggest fanboy i've ever seen. It would be funny if it wasn't so sad you're vasting so much energy on such insignificant issue and everyone around here just thought to themselves..."what a total failure".

    But hey, on the bright-side, you made me jump off that fence and register, so you might not be as useless as you seem.
  • monomer - Thursday, October 1, 2009 - link

    Wow, your proof that Fermi exists is a photo of Huang holding up a mock-up of what the new card is going to look like?

    If that was a real card, and engineering samples existed, why isn't it actually in a PCI-e slot running something? Why were no functioning Fermi cards actually shown at the conference? Why was the ray-tracing demo performed on a GT200?

    Finally, why did Huang say that cards will be ready in "a few short months", if they are actually ready now?

    You need to calm down a little. You also need to work on your reading skills and to stop making up controversies where none exist.

    Yes, Anand pointed out that the memory bandwidth did not double, but in the very same sentence, he mentions that it did not double for the 5870 either.


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