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Inside the Itanium

Posted by ryuzaki0 on from the hammer-time dept.

vanguard writes: "Extreme Tech has a detailed overview of the Itanium. It's fairly long but it's worth your time if such things interest you."

16 of 135 comments (clear)

  1. Better link by jeroenb · · Score: 3, Informative

    Go here to view the entire article on a single page without all the annoying crap around it :)

    1. Re:Better link by Segfault+11 · · Score: 3, Interesting
      ... and for a recent read on Hammer, go here: http://www.hardwaremania.com/reviews_eng/hammer/ha mmer1.shtml

      Of course, for some perspective on the nature of processor speculation, I point you to nearly any issue in Byte's print archive.

      --

      I registered my hate for Jon Katz

  2. Try before you buy by T1girl · · Score: 3, Funny

    There's no guarantee that any calculations you did won't have to be redone with valid data. It's a bit of a gamble, but can pay handsomely if you speculate wisely. Architecture imitates life.

    It was worth reading a long article to come across this nugget of wisdom. I think i'll embroider it on a sampler and hang it in my cube.

  3. Not about 64 bits... by jeroenb · · Score: 4, Insightful

    I've been looking into the IA-64 for the past year orso, and I'm convinced that on the technology side, both the architecture and the implementation are a good thing. What surprises me is that it's still taking quite some time for it to start popping up in actual production environments. Not sure what the reasons for this are.

    First of all, with HP being a co-developer of the entire architecture, they are a big backer of the Itanium. So is Compaq, who sold their entire Alpha technology to Intel to focus on implementing the Itanium in all their high-end products (makes you think, was this all decided because they already knew they were going to merge with HP? Probably...) Dell is still sticking with 100% Intel, so the Itanium will be their bet for capturing more of the high-end segment. Even SGI is selling Itanium workstations (although, with the recent announcement of the MIPS-only, IRIX-only Fuel workstation, they might abandon the Itanium as well.)

    So what's holding it back? I think that although there's now Linux available for it as well as a prerelease version of Windows Server along with some other systems (like HP UX) we still need to see more applications. Databases alone just aren't enough - and with the high prices of Itanium machines (the cheapest dual-Itanium 733 is around $22K at Dell, everyone else is probably more expensive) developers are not really happy about buying a couple of those machines and start hacking. So I think that because we don't see the Itanium much, developers are not investing in writing the software and business are not investing in buying the hardware.

    Maybe Intel should start giving out IA-64 machines to opensource hackers and watch it fly? Where can I submit my address info? :)

    Oh and about the subject of this post, the fact that the Itanium is 64 bits is not really all that important - the fact that a processor is 64 instead of 32 bits doesn't say anything about how fast it is. If you think it does, you can buy my R4400 Indigo2 for $10K :)

    1. Re:Not about 64 bits... by Florian+Weimer · · Score: 3, Informative

      So what's holding it back?

      For real-world numerical applications, using state-of-the-art Intel compilers, the Pentium 4 is faster than the Itanium. Of course, people still use the Itanium because of its substantially larger address space, which is a very, very significant issue. And we can expect the IA-64 architecture to catch up as compilers improve, as it is common with such architectures.

  4. What about power / heat ? by redelm · · Score: 3, Informative
    A nice architectural overview, but there's no mention of power. IIRC, Itanium sucks back 125 Watts!


    Power/heat this high gives system designers problems, plus it can't be easy getting ~100 Amps to&from a chip.


    Otherwise, AFAIK, Linux has working ia64 so code size can be compared. I'd expect 4x x86.

    1. Re:What about power / heat ? by CMiYC · · Score: 3, Informative

      Yeah it is a power hog. For Merced there is a power pod that goes next to each "processor". That pod provides the power to the processor only. Then from there, there power is distributed to the L3, PAL, Core, etc. I'd imagine on the processor's core chip the power is distributed by a signfinicant amount of pins. Otherwise it'd be a bear to get the power evenly to different areas of the die.

  5. What's the point? by 4im · · Score: 3, Insightful

    Except for the Itanium coming from Intel, what's the point? This is a prototype for a new architecture (IA64), prototype proven to be seriously lacking in speed, stability etc. I got to see a dual Itanium prototype from HP a few months ago, and all the comments I got about it were that it essentially sucked.

    Really, if you need 64 bit, why not just go and get yourself some UltraSparc, Alpha etc.? I have gotten myself a used Ultra 30, will soon get an used AlphaServer, and I sure don't need to go buy an expensive, unstable processor that's not even got decent compiler support yet.

    And if it has to be IA64, at the very least wait for McKinley - HP's engineers are supposed to be doing a much better job of IA64 than Intel did. Or even wait for the version after McKinley, which is supposed to profit from good ol' Alpha.

  6. So what's holding it back? by dpilot · · Score: 3, Informative

    How about the fact that VLIW (or EPIC, if you prefer) compiler technology really isn't there yet for general purpose problems? Maybe you can write a program for EPIC and get it to scream, but simply recompiling the ray-tracer (or what-have-you) you already have just won't show much. Take a look on comp.arch for more, especially under X86-64 for evolution vs revolution opinions.

    --
    The living have better things to do than to continue hating the dead.
  7. Can anyone understand this? by Pedrito · · Score: 3

    I've done my share of assembly language, from 8-bit Ataris to 32-bit Intels, to IBM/390 mainframes.

    I can't even conceive of having to write assembly code for these monsters. Anyone happen to browse through the instruction set reference? All 900+ pages of it? It's all cryptic as hell. I could sooner build a rocket bound for Pluto than write a simple recursive factorial program in IA-64 assembly.

    I sure hope someone can figure it out. I doubt I'll be doing any assembly optimizations in the future.

  8. cache hits by johnjones · · Score: 3, Interesting

    the real problem for intel is that the arch does badly for programs that are not cache hitters

    they took one look at the people trying to do predictive memory loads and decided not too. this was a LONG time ago and now people have solved the problem so that most of the time you can get things from cache

    IA64 fails to get things from cache too well (one of the reasons why they stuck such a large one on) so suffers from the latencey problems more than most

    simple

    regards

    john 'try runnning spec marks on it' jones

  9. Overview? How about Autopsy... by HiredMan · · Score: 4, Informative

    HP decided as early as 1996 that the then "Merced" project would not overtake their PA-RISC arch and essentially walked away from the the project.

    Years late the "Itanium" finally ships (although no one buys it) as Intel says, "But wait for McKinley! Then it will really work!"

    The McKinley is the product of the "rethought" Merced project. McKinley is shipping later this year - with a completely different socket system so even the arch surrounding the "Itanium" is dead in the water.

    Let's compare this to the REAL competition:

    IBM Power4 1.3GHz - shipping for a while now:
    SPECint2000 = 814 SPECint_base2000 = 790
    SPECfp2000 = 1169 SPECfp_base2000 = 1098

    Sun UltraSparc III Cu 1.05GHz:
    SPECint2000 = 610 SPECint_base2000 = 537
    SPECfp2000 = 827 SPECfp_base2000 = 701

    Even the best Itanium 800Mhz reported int numbers are:
    SPECint2000 = 365 SPECint_base2000 = 358
    (Same box) SPECfp2000 = 610 SPECfp_base2000 = 526

    Even if the McKinley (which doesn't ship for 6 months or so) produces double the Itanium numbers it'll still lag the currently shipping Power4 chips.

    Remember the hype and FUD surrounding the launch of the "Itanium" chip that eventually hasn't even caused a ripple in the marketplace? Intel has sunk billions into this EPIC project and refuses to let it go even though it's years late so far hasn't produced the clear advantage over the RISC arch it was supposed to make obsolete. In many cases the "consumer" chips continue to make better results than the "server" chip series - and with AMD knocking on Intel's door throttling back production/performance of the consumer ship is not an option.

    Will the McKinley better than the Itanium? Certainly.
    Will it be compelling? Wihtout Intel behind it - probably not. (Alpha was the clear performance winner for so long but couldn't get any traction.)
    Is VLIW^H^H^H^H EPIC the future of computing? "Answer unclear... ask again later." ;)

    =tkk

    --
    Bill Gates - Creationist?!?
  10. it's always been about the compilers by jrst · · Score: 4, Interesting

    Many of the comments about compiler technology in this thread could be taken verbatim from discussions about RISC architectures 20 years ago. Or from the HLL (high level language) architecture discussions 30 years ago. (Anyone remember the cries for "closing the semantic gap" between processor's and languages? No? Point made.)

    Hardware is getting more complex; it takes more sophistication to deal with it. Binding a (general purpose) processor to a language in order to make language implementation easier is exactly the wrong way to support a wider variety of languages. Making the most of a processor's capabilities is what compilers are for. That's what compiler writers get paid for.

    That's not to say I'm in love with the Itanium. At first glance I found it a baroque rehash of old ideas. But time--and compiler writer's--will tell.

  11. A visionary's gutfeel regarding 64-bit widespread by pinkpineapple · · Score: 3, Interesting

    When Steve Jobs was asked about what he was envisioning regarding 64-bit processor adoption (related to the fact that at that time, IBM came out with the Power4 kick ass cpu), his reply was that it would take about 10 years for the common of the mortals (you and me mostly, but not him :-) to see 64-bit systems on the shelves at Fry's or CompUSA.

    Given that it was coming out from the mouth of the CEO of a company that :
    - can afford the move quickly and nicely (PowerPC architecture is clean compare to IA-64 + x86 and is 32-bit backward compatible).
    - had successfully shifted the kernel to a clean replacement (less kludges) allowing the transition in a blink of an eye (ok, maybe 6 months)
    - has a park of installed machines in places like labs (see gentech), and design studio.
    - runs applications that would benefit the most are all in the Apple camp (A/V and number crunching apps like photoshop, maya and final cut)
    - develops a big chunck of the major apps for its platform leading the way in term of design and adoption of new tech.

    it would seem that we have about 8 more years of 32-bit glory or galore in front of us, before the current cpu architectures get displaced and eventually die.

    Which 64-bit architecture will succeed is not clear today. Knowing that MS doesn't rush their OS out of the door to support the IA-64, it seems to be a little premature to tell.

    PPA, the girl next door.

    --
    -- I feel better now. Thanks for asking.
  12. Gad, what a turkey by Animats · · Score: 3, Interesting
    I can't see why Intel bothered with this thing. Intel pioneered mainstream superscalar out-of-order machines with the Pentium Pro/II/III architecture, which made it possible to make CISC architectures go fast. That was a major achievement. It made classic RISC obsolete - why put up with the code bloat?

    Then came the Inanium. VILW, code bloat, ugly architecture, requires near-omniscience from the compiler, very tough to program in assembler, a power hog, and with mediocre performance. If anybody else had launched this, it would have died before first shipment. As it is, it's dying anyway. Dell dropped their Itanium workstation recently. The Itanium may end up as a niche product, like the forgotten i860, i960, and iapx432 processors.

    I'm hearing rumors of a new 64-bit machine from Intel that's basically an improved x86, like the AMD Sledgehammer. That may be what actually gets used.

  13. Intel's compiler writers..... by zerofoo · · Score: 3, Insightful

    Lucky for intel, they do have a very talented bunch of compiler writers. Their work on P4 optimizations basically saved the P4 from itself. The problem is getting the rest of the complier world to support Intel's new architecture. Like them or not; Visual C and GCC are hugely popular, and until those guys support Itanic, Intel won't sell many of these newfangled processors.

    -ted