Introduction

"What you have seen is a public demonstration of 4 GHz silicon straight off our manufacturing line. We have positive indications to be able to take Netburst to the 10 GHz space."

"While architectural enhancements are important, Intel intends to continue its lead in raw speed. Otellini demonstrated a new high-frequency mark for processors, running a Pentium 4 processor at 4.7 GHz."

The first assertion was made at IDF Spring 2002, and the second press release was broadcasted after Fall IDF 2002. Fast forward to the beginning of 2004, and we read in the Prescott presentation: "2005-2010: the era of thread level parallelism and multi-core CPU technology. " What happened to "the 10 GHz space"?


Fig 1. "2005-2010: the era of thread level parallelism and multi-core CPU technology ".

The presentation of the new 6xx Prescott even states that Intel is now committed to " Adding value beyond GHz". This sounds like Intel is not interested in clock speeds anymore, let alone 10 GHz CPUs.

Already, the hype is spreading: Dual core CPUs offer a much smoother computing experience; processing power will increase quickly from about 5 Gigaflops to 50 gigaflops and so on. It is almost like higher clock speeds and extracting more ILP (Instruction Level parallelism), which has been researched for decades now, are not important anymore.

At the same time, we are hearing that "Netburst is dead, Tejas is cancelled and AMD's next-generation K9 project is pushed back." Designs built for high clock speeds and IPC (Instructions per Clock) are no longer highly regarded as heroes, but black sheep. They are held responsible for all the sins of the CPU world: exploding power dissipation, diminishing performance increases and exorbitant investments in state of the art fabs to produce these high clock speed chips. A Prescott or Athlon 64 CPU in your system is out of fashion. If you want to be trendy, get a quad core P-m, also known as Whitefield [2], made in India.

To the point

I am exaggerating, of course. A good friend of mine, Chris Rijk, said: "PR departments having no 'middle gears': they either hype something to great lengths, or not at all." Trying to understand what is really going on is the purpose of this article. We are going to take a critical look at what the future CPU architectures have to offer. Is the traditional approach of increasing IPC and clock speed to get better performance doomed? Does multi-core technology overcome the hurdles that were too high for the single-core CPUs? Are multi-core CPUs the best solution for all markets? Will multi-core CPUs make a difference in the desktop and workstation market?

In this first instalment, we explore the problems that the current CPU architectures face. The intention is to evaluate whether the solution proposed by Intel and other manufactures is a long-term solution, one that really solves those problems. We will also investigate one CPU in particular, the Intel Prescott. So, basically there are 4 chapters in this article that will discuss:

  • The problems that CPU architects face today: Wire Delay, Power and the Memory wall.
    Chapter 1 - The brakes on CPU power
  • The reason why Intel and others propose dual core as a solution to these problems.
    Chapter 2 - Why single core CPUs are no longer "cool"
  • Whether or not these problems can be solved without dual core.
    Chapter 3 - Containing the epidemic problems
  • A case study of the Intel Prescott.
    Chapter 4 - The Pentium 4 crash landing

Although Intel is undeniably the industry leader in the CPU market, this doesn't always mean that the solutions proposed are the right ones. For example, remember MMX, which was a technology that should have turned the (x86-based) PC into a multimedia monster. In hindsight, the critics were right. MMX was little more than a marketing stunt to make people upgrade.

The first implementation of hyperthreading on Intel's Foster Xeon (Willamette Xeon) was turned off by default by all OEMs. And hyperpipelined CPUs with 30+ stages turned out to be an impressive, but pretty bad idea.

In other words, not all hypes have turned out to be beneficial for the customer. Millions of customers are still waiting for the rich content on the Internet that is enabled by and runs so much faster on the Netburst architecture...


CHAPTER 1: The brakes on CPU power
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  • AnnoyedGrunt - Tuesday, February 08, 2005 - link

    It's possible that 22 was referring solely to the grammar of the sentence, which could potentially make more sense if it was rewritten as, "while other applications will REQUIRE exponential investments in develpment....."

    Very good article overall, but some portions could be polished a bit perhaps to make it easier for people only slightly familiar with processor details (people like myself) to understand.

    Really looking forward to part 2!

    -D'oh!
    Reply
  • JarredWalton - Tuesday, February 08, 2005 - link

    23 - Not at all. Have you ever tried writing multi-threaded code? If it take 12 months to write and debug a single-threaded program that handles a task, and you try to do the same thing in multi-threaded code, I would expect 24 to 36 months to get everything done properly.

    Let's not even get into the discussion of the fact that not all code really *can* benefit from multi-threadedness. I had a similar conversation with several others in the Dual Core AMD Roadmap article. You can read the comments there for additional insight, I hope:

    http://www.anandtech.com/talkarticle.aspx?i=2303
    Reply
  • cosmotic - Tuesday, February 08, 2005 - link

    "while the other applications will see exponential investments in development time to achieve the same performance increase." Thats a really stupid statement. Reply
  • cosmotic - Tuesday, February 08, 2005 - link

    That first image really sucks. You should at least make it look decent. It looks like crap now. Reply
  • IceWindius - Tuesday, February 08, 2005 - link

    Math hurts, and thus my head hurts.......


    Either way, Intel finally admits they fucked up and AMD spanked them for it. Justice is served.
    Reply
  • faboloso112 - Tuesday, February 08, 2005 - link

    only about halfway through the article but this is a damn good article.

    not a fanboi of any sort but i certainly do hate intel's pr team.

    i think the reason amd has done well for itself is because it doesn't pride itself nor relies of fake product specs and their exaggerated capabilities and scalability...unlike intel...and ill admit...i got cought up in the hype too with the whole 10ghz thing at the time because based on moore's law and how things had been going w/ the clock speed jumps...i thought one day it would be possible...but look at where the prescott stands now...and look at how instead of blabbing about 10ghz..they talk of multi-core cpu.

    i think ill stop talking now and return to the article...
    Reply
  • erikvanvelzen - Tuesday, February 08, 2005 - link

    i eat these sort of articles about cpu's, memory and the like which have references to hardware which i actually use.

    If you like this, check out these articles by John 'Hannibal' Stokes @ arstechnica.com:
    http://arstechnica.com/cpu/index.html
    http://arstechnica.com/articles/paedia/cpu.ars
    Reply
  • jbond04 - Tuesday, February 08, 2005 - link

    AWESOME article, Johan. Good to see someone do some real research regarding the Prescott processor. Keep up the good work! Reply
  • Oxonium - Tuesday, February 08, 2005 - link

    Johan used to write very good articles for Ace's Hardware. I'm glad to see him writing those same high-quality articles for Anandtech. Keep up the good work! Reply
  • BlackMountainCow - Tuesday, February 08, 2005 - link

    Wow, very interesting read. Finally some stuff based on real facts and not some "Prescott just sux" stuff. Two thumbs up! Reply

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