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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  • PorscheRacer - Thursday, October 1, 2009 - link

    I have no clue what the red rooster thing implies, and I never understood why people called nVIDIA the green goblin. Until now. You, sir, have made it clear to me. They are called the green goblin, because that's where the trolls come from. Like wow. Your partisan and righteous thinking has no merit, no basis except conjecture and criticism. Save a keyboard, chill out and let's see if you can post anything in here without using the words, nVIDIA, ATI, red rooster, green goblin, and anything with ALL CAPS.

    It's fine to be passionate about something. But to exessive extents that push everyone else away and leave people ashamed, discouraged and embarrased; that's not how to win hearts and minds. I can already see you getting riled up over this post telling you to chill out....
  • SiliconDoc - Friday, October 2, 2009 - link

    Hmmmm, that's very interesting. First you go into a pretend place where you assume green goblin is something "they call" nVIDIA, but just earlier, you'd never seen it in print before in your life.
    Along with that little fib problem, you make the rest of the paragraph a whining attack. One might think you need to settle down and take your own medicine.
    And speaking of advice, your next paragraph talks about what you did in your first that you claim noone should, so I guess you're exempt in your own mind.
  • kirillian - Thursday, October 1, 2009 - link

    Yall...seriously...leave the poor NVidia Fanboy alone. His head is probably throbbing with the fact that he found his first website (other than HardOCP) that isn't extremely NVidia biased.
  • SiliconDoc - Friday, October 2, 2009 - link

    Gee, I find that interesting that you know all about bias at other websites...
    So that says what again about here ?
  • silverblue - Thursday, October 1, 2009 - link

    The 5870 is but one single GPU. The 295 is two and costs more. The 4870X2/CF is also a case of two GPUs. A 5870X2 would annihilate everything out there right now, and guess what? 5870 CF does just that. If money is no object, that would be the current option, or 5850s in CF to cut down on power usage and a fair amount of the cost without substantially decreasing performance.

    By stating "if someone wants to get their next-gen performance now", of course he's going to point in the direction of ATI as they are the only people with a DX11 part, and they currently hold the single GPU speed crown. This will not be the case in a few months, but for now, they do.
  • SiliconDoc - Friday, October 2, 2009 - link

    I kinda doubt the 5870x2 blows away GTX295 quad, don't you ?
    --
    Now you want to whine cost, too, but then excuse it for the 5870CF. LOL.
    Another big fat riotous red rooster.
    Really, you people love lies, and what's bad when it's nvidia, is good when it's ati, you just exactly said it !
    ROFLMAO
    --
    Should I go get a 295 quad setup review and show you ?
    --
    How come you were wrong, whined I should settle down, then came back blowing lies again ?

    There's no DX11 ready to speak of, so that's another pale and feckless attempt at the face save, after your excited, out of control, whipped up incorrect initial post, and this follow up fibber.

    You need to settle down. "I want you banned"
    Finally, you try to pretend you're not full of it, with your spewing caveat of prediction, "this will not be the case in a few months" - LOL
    It's NOT the case NOW, but in a few months, it sure looks like it might BE THE CASE NO MATTER WHAT, unless of course ati launches the 5870x2 along with nvidia's SC GT300, which for all I know could happen.
    So, even in that, you are NOT correct to any certainty, are you...
    LOL
    Calm down, and think FIRST, then start on your rampage without lying.
  • silverblue - Friday, October 2, 2009 - link

    My GOD... you're a retard of the highest order.

    Why would I want to compare a dual GPU setup with an 8 GPU setup? What numpty would do that when it would logically be far faster? Even a quad 5870 setup wouldn't beat a quad 295 setup, and you know what? WE KNOW! 8 cores versus 4 is no contest. Core for core, RV870 is noticeably faster than the GT200 series, but you're the only person attempting to compare a single GPU card to a dual GPU card and saying the single GPU card sucks because it doesn't win.

    And where did I say "I want you banned"? As someone once said, "lay off the crack".
  • SiliconDoc - Friday, October 2, 2009 - link

    Aren't you the one who claimed only ati for the next gen performance ?
    Well, you really blew it, and no face save is possible. A single NVIDIA card beats the best single ati card. PERIOD.

    It's true right now, and may or may not change within two months.
    PERIOD.
  • silverblue - Friday, October 2, 2009 - link

    No, I said that ATI currently has the single GPU crown. Not card - GPU. In a couple of months, ATI may have the 5870X2 out, and that WILL send the 295 the way of the dodo if it's priced correctly.

    No face saving necessary on my part.
  • Zaitsev - Wednesday, September 30, 2009 - link

    ^^LOL. I don't see what all the bickering is about. If you're willing to wait a few more months, then you can buy a faster card. If you want to buy now, there are also some nice options available. Currently there are 5 brands of 5870's and 1 5850 at the egg.

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