The Prelude

As Intel got into the chipset business it quickly found itself faced with an interesting problem. As the number of supported IO interfaces increased (back then we were talking about things like AGP, FSB), the size of the North Bridge die had to increase in order to accommodate all of the external facing IO. Eventually Intel ended up in a situation where IO dictated a minimum die area for the chipset, but the actual controllers driving that IO didn’t need all of that die area. Intel effectively had some free space on its North Bridge die to do whatever it wanted with. In the late 90s Micron saw this problem and contemplating throwing some L3 cache onto its North Bridges. Intel’s solution was to give graphics away for free.

The budget for Intel graphics was always whatever free space remained once all other necessary controllers in the North Bridge were accounted for. As a result, Intel’s integrated graphics was never particularly good. Intel didn’t care about graphics, it just had some free space on a necessary piece of silicon and decided to do something with it. High performance GPUs need lots of transistors, something Intel would never give its graphics architects - they only got the bare minimum. It also didn’t make sense to focus on things like driver optimizations and image quality. Investing in people and infrastructure to support something you’re giving away for free never made a lot of sense.

Intel hired some very passionate graphics engineers, who always petitioned Intel management to give them more die area to work with, but the answer always came back no. Intel was a pure blooded CPU company, and the GPU industry wasn’t interesting enough at the time. Intel’s GPU leadership needed another approach.

A few years ago they got that break. Once again, it had to do with IO demands on chipset die area. Intel’s chipsets were always built on a n-1 or n-2 process. If Intel was building a 45nm CPU, the chipset would be built on 65nm or 90nm. This waterfall effect allowed Intel to help get more mileage out of its older fabs, which made the accountants at Intel quite happy as those $2 - $3B buildings are painfully useless once obsolete. As the PC industry grew, so did shipments of Intel chipsets. Each Intel CPU sold needed at least one other Intel chip built on a previous generation node. Interface widths as well as the number of IOs required on chipsets continued to increase, driving chipset die areas up once again. This time however, the problem wasn’t as easy to deal with as giving the graphics guys more die area to work with. Looking at demand for Intel chipsets, and the increasing die area, it became clear that one of two things had to happen: Intel would either have to build more fabs on older process nodes to keep up with demand, or Intel would have to integrate parts of the chipset into the CPU.

Not wanting to invest in older fab technology, Intel management green-lit the second option: to move the Graphics and Memory Controller Hub onto the CPU die. All that would remain off-die would be a lightweight IO controller for things like SATA and USB. PCIe, the memory controller, and graphics would all move onto the CPU package, and then eventually share the same die with the CPU cores.

Pure economics and an unwillingness to invest in older fabs made the GPU a first class citizen in Intel silicon terms, but Intel management still didn’t have the motivation to dedicate more die area to the GPU. That encouragement would come externally, from Apple.

Looking at the past few years of Apple products, you’ll recognize one common thread: Apple as a company values GPU performance. As a small customer of Intel’s, Apple’s GPU desires didn’t really matter, but as Apple grew, so did its influence within Intel. With every microprocessor generation, Intel talks to its major customers and uses their input to help shape the designs. There’s no sense in building silicon that no one wants to buy, so Intel engages its customers and rolls their feedback into silicon. Apple eventually got to the point where it was buying enough high-margin Intel silicon to influence Intel’s roadmap. That’s how we got Intel’s HD 3000. And that’s how we got here.

Haswell GPU Architecture & Iris Pro
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  • s2z.domain@gmail.com - Friday, February 21, 2014 - link

    I wonder where this is going. Yes the multi core and cache on hand and graphics may be goody, ta.
    But human interaction in actual products?
    I weigh in at 46kg but think nothing of running with a Bergen/burden of 20kg so a big heavy laptop with ingratiated 10hr battery and 18.3" would be efficacious.
    What is all this current affinity with small screens?
    I could barely discern the vignette of the feathers of a water fowl at no more than 130m yesterday, morning run in the Clyde Valley woodlands.
    For the "laptop", > 17" screen, desktop 2*27", all discernible pixels, every one of them to be a prisoner. 4 core or 8 core and I bore the poor little devils with my incompetence with DSP and the Julia language. And spice etc.

    P.S. Can still average 11mph @ 50+ years of age. Some things one does wish to change. And thanks to the Jackdaws yesterday morning whilst I was fertilizing a Douglas Fir, took the boredom out of a another wise perilous predicament.
    Reply
  • johncaldwell - Wednesday, March 26, 2014 - link

    Hello,
    Look, 99% of all the comments here are out of my league. Could you answer a question for me please? I use an open source 3d computer animation and modeling program called Blender3d. The users of this program say that the GTX 650 is the best GPU for this program, siting that it works best for calculating cpu intensive tasks such as rendering with HDR and fluids and other particle effects, and they say that other cards that work great for gaming and video fall short for that program. Could you tell me how this Intel Iris Pro would do in a case such as this? Would your test made here be relevant to this case?
    Reply
  • jadhav333 - Friday, July 11, 2014 - link

    Same here johncaldwell. I would like to know the same.

    I am a Blender 3d user and work on cycles render which also uses the GPU to process its renders. I am planning to invest in a new workstation.. either a custome built hardware for a linux box or the latest Macbook Pro from Apple. In case of latter, how useful will it be, in terms of performance for GPU rendering on Blender.

    Anyone care to comment on this, please.
    Reply
  • HunkoAmazio - Monday, May 26, 2014 - link

    Wow I cant believe I understood this, My computer archieture class paid off... except I got lost when they were talking about n1 n2 nodes.... that must have been a post 2005 feature in CPU N bridge S Bridge Technology Reply
  • systemBuilder - Tuesday, August 05, 2014 - link

    I don't think you understand the difference between DRAM circuitry and arithmetic circuitry. A DRAM foundry process is tuned for high capacitance so that the memory lasts longer before refresh. High capacitance is DEATH to high-speed circuitry for arithmetic execution, that circuitry is tuned for very low capacitance, ergo, tuned for speed. By using DRAM instead of SRAM (which could have been built on-chip with low-capacitance foundry processes), Intel enlarged the cache by 4x+, since an SRAM cell is about 4x+ larger than a DRAM cell. Reply
  • Fingalad - Friday, September 12, 2014 - link

    CHEAP SLI! They should make a cheap IRIS pro graphics card and do a new board where you can add that board for SLI. Reply
  • P39Airacobra - Thursday, January 08, 2015 - link

    Not a bad GPU at all, On a small laptop screen you can game just fine, But it should be paired with a lower CPU, And the i3, i5, i7 should have Nvidia or AMD solutions. Reply

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