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Inside the Itanium
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."
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Go here to view the entire article on a single page without all the annoying crap around it :)
Wow, 328 registers. Does it mean that it will be more efficient to declare all variables in a single function than using multiple functions (due to scope of variables that restricts the efficient usage of so many registers)?
{{.sig}}
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.
Does anyone here know why Intel named this processor with such a strange name ?
Everybody associates Itanium with Italy - a country with Mafia, corrupt goverment and now a right wing pre-dictator president.
More literally minded people might associate Itanium with Itaka - the homeland of Odysseus a greek hero who drove gods mad and never made it home in time.
So why this strange name which everybody associates with negative effects ?
Does the Itanium has timing problems ?
Does it drive the users crazy ?
Does it corrupt the operating systems and make viruses take over the system ?
Does it suppress all program which don't use right aligned doubles ?
Owner of a Mensa membership card.
The price? $7,999 at the time.
Open source are poor lusers no matter if they use 386 or Itanium.
What is so special about the Itanium other than the fact that it's from Intel? We've had 64-bit processors for years now. Moreover, it's not like everyone is going to ditch the IA32 architecture overnight and go to Itanium. It seems to me that anyone who needs/wants 64-bit computing already has it.
Sig (appended to the end of comments you post, 120 chars)
Is there ANY Itanium hardware that actually delivers good performance for the money yet?
Is there ANYONE doing ANYTHING useful with them yet?
As far as I can tell, current Itanium stuff is a mere curiosity.
Intel is making an enormous gamble with IA-64, it is a huge investment and the whole thing may blow up in their face.
AMD is taking the 'safe road' -- bolting 64bit onto an existing design, taking advantage of the huge momentum of the x86 architecture.
Intel on the other hand is going to have to spend a huge amount of effort getting the Itanic moving.
Will be interesting to see how things develop. Will AMD's 64bit products derail Intel's efforts? Can they crack the 64bit server market fast enough and make IA-64 irrelevant? Stay tuned!!
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
Just the other day, I sat in on one of the compiler developers of the itanium giving a seminar. Needless to say, most of the group went to sleep the moment he started talking about the instructions. The assembly seems awfully arcane, so it's likely someone could go insane before speeding up anything :).
:)
Anyway, To all those who think it's performance is rather low, It seems more like a proof of concept chip rather than something intended for mass production.
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.
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 :)
Or my R10000 Indigo2 for $20K... at least it runs "IRIX64" the 64-bit kernel and the 64-bit ABIs.
elwood 6# uname -aR
IRIX64 elwood 6.5 6.5.15m 01091821 IP28
AFAIK, the only SGIs that use the R4400 in a 64-bit manner are the Challenge L, Challenge XL, and (original) Onyx. R4400 in desktop machines is limited to 32-bit support for memory contraint issues. 64-bit on the desktop from SGI requires an R8000/R10000 based Indigo2, R10K/R12K/R14K Octane/Octane2, or R14K Fuel. All other desktop configurations are limited to O32 and N32.
Everyone is just waiting for McKinley.
I don't feel that any of the current reports are aimed at people such as myself, and don't feel that I'm getting the real deal in terms that I understand.
I understand what a register is, the advantages of 64bit, 128bit etc., even what a pipeline is.
What I would like to see is a bullet pointed list of advantages put in executive summary style, dumb-down, type!
Also, I read a few years ago about Elberus, who have some pretty neat claims here:http://www.elbrus.ru/mcst_e/proect_e/e2k_arch _e.htm
You may be interested in their claims.
e4 e5
The most important thing about 64-bit chips is that they allow an address space of over 4GB. This is a real fully addressable >4GB space, not some 36-bit hack like the current intel 32-bit chips allow.
:)
In the EDA industry (Electronic Design Automation i.e. tools for making computer chips) we routinely hit the 4GB memory limit. 99% of EDA tools run on Solaris but EDA companies are slowly recompiling their apps to be 64-bit clean on Solaris.
Meanwhile Linux is picking up steam in the EDA world but the 4GB limit is holding it back. We're forcing into complex partitioning of our chips to break it into small enough chunks to fit under 4GB.
We need cheap (non-SPARC) 64-bit chips, say like oh AMD Hammer?
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.
It will rarely save registers on CALL (unless one is using a lot of registers). It uses (stupid) SPARC-style register windows (or register "frames" as they're calling them now). i.e. it renames registers instead of saving them.
Software is by far more costly and complex than processors these days, and we just don't need extra complications in the form of processors that shift even more complexity into software.
I can't pretend to know what a "good" 64bit architecture should look like. But for the time being, something like Alpha or AMD Hammer seems like a better choice to me. And even Intel seems to be reconsidering and keeping a 64bit version of the Pentium as a backup strategy.
eax, ebx, ecx, edx, esi, edi, ebp.
plus cs, ds, esp and eip which shouldn't be used for calculations
I think the problem is that Itaniums are too expensive to buy. At home, I'd gladly byn an Itanium instead if I could afford one (making it use less power would be a plus too. I think cpu manufacturers are cheating today, just have a bigger fan and sell it as a faster CPU. They should have say 10W to play with and nothing more.)
The problem is, I guess, that they aren't producing enough CPUs to make it cheep. But to make people use it I think they have to accept an initial loss and sell them cheaper just to get an userbase.
Linux/some unix would fit my needs fully and I'd be happy using an Itanium over a IA32/athlon solution and when the market is big enough for a game launcher environment (pronounced as "windows") that would be a big bonus.
So, Intel, please don't screw this up. It's not that often you release a good processor.
Google has a cache of the article. Please don't slashdot rhe maoin server!
Fictional Conversation between an Abacus Salesman and a Consumer
Abacus Salesman: "It's a fully programmable addition unit"
Consumer: "Uhhh....it doesn't have any little beads...how am I supposed to add?"
Abacus Salesman: "You program it with a FP MAC adder of Zero and ....blah blah blah."
Consumer: "Uh...sure, now tell me why I don't want to buy a regular abacus?? You know, the kind that does math?"
Itanium is making the compiler do alot of work! This presents a gigantic challenge for compiler writers. My concern is with GCC. We all know that GCC does not produce the tightest, fastest code. For IA-32, this is not a big deal because there is only so much optimization that can be done with that ISA (instruction set architecture). However with Itanium, the compiler will probably affect runtime execution speed by 100% or more. Will the GCC people have the resources and expertise to handle IA-64 (Itanium)??
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.
Altogether, that can't be good for the industry in the long run. We need more, not less, support for new software architectures and languages. Instruction scheduling and parallelization are things that a processor can handle much easier than a static compiler because the processor can efficiently keep runtime statistics on what a program actually does.
Potentially a better approach to me appears to be hyperthreading, which redefines the problem. No, individual threads won't get very high performance, but code generation is pretty easy, and (unlike VLIW) the programmer can take explicit control of parallelism at a higher level through threads. To me, that seems like an overall better approach.
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.
First thing that occured to me is that the arch is a little weird in places. No integer multiply, wtf? Of course, then it occured to me: who uses integer multiply? The main reason to use them would be mainly in rasterization code in a graphics pipeline. Since integer-based rasterization went out with MMX, this doesn't matter. Overall, the arch seems pretty clean, a hell of a step up from x86, anyway. And, the initial performance seems pretty good, so it seems to work. While the whole EPIC thing could mean hell for compiler writers, remember that Intel's ICC has been doing parallization on x86 procs for years now, and does a damn good job of it. I can't wait for Deerfield to come out so I can get to chose between that and a K8 for me next PC ;)
A deep unwavering belief is a sure sign you're missing something...
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
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?!?
It sucks, nuf said.
A bit more specific, look at the bottom of the article where it mentions the "use merced for development, mcinley will actually sell". And the fact that even Dell no longer sells Itanium.
Sanity check:
system specint/specfp cost
Hp server rx4610 342/701 $23k
AMD XP2000+ epox 8HK+ 734/642 $1k
Keep in mind that the Itanics are supposed to be for the server market, so the specint figures will more likely track actual performance. Intel has been claiming that McKinley will be a vast improvement (actuall claims seem to have been steadily downgraded from "dominate the market" to "actually sell a few" to "won't make management look like complete idiots"...). Present claims of McKinley performance are 1.5 to 2.0 times Itanic performance, i.e. unlikely to keep up with Athlon, let alone the hammer.
Why does it suck?
While Intel does know how to design processors, the architectures are annother story. Aside from the 8086 kludge, intel has produced such "successors" as the 432 and the 860. The 432 was even slower compared to the competition as the itanic, and the 860 was even harder to write a compiler for (and impossible to write an interupt handler, let alone an OS).
EPIC is supposed to be VLIW with enough "extras" to allow the compiler to write code that won't require out-of-order execution. It is also supposed to allow intel to create several generations of compatible chips (something hard to do with pure VLIW). Somewhere along they way they forgot that the point of VLIW is to make execution simple. The lessons of RISC and the Cray machines is that the more simple and clean an architecture is, the faster it can go. Check out how long it takes to explain the architecture, then examine Alpha and ARM. Granted, ease of explaining does not always translate into ease of design, but it ussually does, and certainly did in this case.
What now?
It looks like the architecture of the future is x86-64. Hammer should appear this year (maybe not for sale, but at least samples). Intel is claimed to have a project called Yamhill that adds AMD compatiblity to the next generation X86. Right now, any support at intel for x86-64 appears to be a CLM (Career Limiting Move and no, it is still a CLM to support it now even after yamhill is enabled). After McKinley goes down in flames (there doesn't seem to be a chance of anything else), it will be interesting to see how long it takes intel to produce anything AMD compatible. Assuming that the next generation of X86 was started after the Pentium 4 finished, that would place it about 4 years from now. By the time the politics get straightened out, that is likely the earlies option (rushing that job will just make it happen later).
Why x86-64?
Anyone familiar with the x86 architecture ussually runs away in horror at the thought of actually using/designing one. Having said that, the 386 architecture fixes almost all of the problems with the 8086/80286. The problems left are:
variable length instructions - this problem has basically disappeard, all modern high power CPUs have bigger problems than this.
insufficent registers - hammers doubles the number of registers (note that itanics 200+ registers become a hindrence if not fully used).
addressing size (32bits) - obviously hammer fixes this.
In summary, intel had a chance to create a usable architecture (anything noticably better than X86 probably would have worked), and would simply owned the market. It is possible that some PHBs thought that anti-trust laws might actually be inforced and then created an architecture too complex to clone. If so, they certainly did so, admitedly making one too complex to build themselves.
Scott
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.
Competing with risc processors? Want to fight with the big boys? Wouldn't it then make sense to actually produce a RISC processor? Just a question.
If they want to call it RISC, then don't make the instructions so large, don't include hundreds of possible instructions, and make the clock cycle time shorter.
Where have the basics of RISC gone?
The PPC which the Power4 is a derivative is the cleanest Risc architecture and with IBM's design expertise and manufacturing prowess guarantees it will stomp on the competition. VLIW in and of itself has not come into the stage where it is a good design concept it is not mature enough. Not only that Intel EPIC goes further than VLIW, IA64 is like experimental and Intel is retarded for not just buying the Alpha processor cleaning up the instruction set and designing a super fast processor based on it.
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.
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.
your computer case will melt with one of these in there, they draw more power and consume more board real estate than an aircraft carrier! 80 watts to run a CPU? give me a fscking break. anything over 10 watts is crime.
I wish they'd stop providing backwards compatability in hardware. It makes the chips more expensive unnecessarily.
The Macs jumped to PPC with software backwards compatability. Same with SUN jumping to Sparc.
They did the RISC transition years ago and have not looked back.
Just do it! (TM)
As far as I can tell, current Itanium stuff is a mere curiosity.
Well right there you have already invalidated the rest of your comment. Intel is not going to have to do anything to get their IA64 architecture moving.
As announced, HP's new PA-RISC chipset will support both McKinley and their RISC processor. Sounds crazy but HP is doing it.
Furthermore nobody and I mean nobody is developing anything for AMD's 64bit systems. On the other hand I have seen significant interest in McKinely. True enough, Merced is just considered a development platform and is pretty much dead in the water. I work for a test and measurement company and I deal directly with our front side bus solutions. You are wrong. AMD is facing the same problems in the IA64 arena that they are in the IA32 arena. Intel's chips say Intel and theirs say AMD. So everybody is ignoring them, for now.
This is not to say that AMD can't come in beat them. I am just saying that Intel's solutions are already in development in many of the high-end server labs. I haven't seen a single group working on AMD's 64bit proc, nor have I been asked if we plan on supporting it.
I sure hope someone can figure it out. I doubt I'll be doing any assembly optimizations in the future.
I've had to do worse, our logic analyzers have to decode the bus traffic to figure out what was going on. As you can imagine, the fact that 1 OP code could mean 4 different thigns depending on when it shows up (or what happened before it) poses a significant challenege. You might say "big deal." Sure, big deal, if you are developing a system. We have to be able to provide tools that are bug free BEFORE the first silicon hits market. That way when a guy in a lab encounters what looks like a bug isn't fighting our mistake.
I fear one day we are going to get to a point where we can't provide a solution for hardware engineers to probe their system with.
If you want to know more technical details about Linux on the Itanium Architecture, David and Stephane just released a book "IA-64 Linux Kernel: Design and Implementation". David was signing copies at HP's booth at LinuxWorld NY.
I know that he said that, but perhaps he didn;t see the the PPC roadmap on Motorolas website recently. The G5 is 64-bit and is 32-bit backwards compatable.
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
Unobtainium
-
- - You can't take something off the Internet! That's like trying to take pee out of a swimming pool.
So *that's* why it's taken so long for this stuff to get to market! :-) You're not able to design bigger chips because your current design tools need the bigger chips to run on....
Bill Stewart
New Fast-Compression-only CPR http://preview.tinyurl.com/dy575ks
Come on, admit it guys, no one cares.
> Furthermore nobody and I mean nobody is
> developing anything for AMD's 64bit systems.
It doesn't matter. AMD will sell plenty of Hammer chips in their usual markets, who will just use it as a faster 32bit x86 chip. (Just like the 386 was used as a faster 16bit chip when it came out.)
BUT one day someone will wake up and realize that Hammer makes for fast, cheap, cool and backwards compatible servers. And then Intel will release their secret x86-64-compatible CPU, and IA64 will be cancelled.
This is good for Intel, but not for anybody else. Go back and look at Intel CPU prices from just before AMD processors caught up.
And that's the real reason for the Inanium.
This register business is totally out of control. Lets just get rid of them and have something like a 'level 0' cache. TI used to have a processor with only three registers, that used memory for everything else. I think it is ultimately easier to just have 256 high speed registers that simulate memory locations. (If you take out the registers needed to manage all these registers and transistors to handle renaming etc, you could get 1K of registers).This also makes assembly language much easier. Want to multiply two numbers, just multiply the memory locations directly. Got some tight counting loops, these will be done directly in registers. How is this going to be handled with MP machines, NUMA seems to be an obvious answer. The caching of memory to registers would have to be very fine grained, of course. In the long run, this appears to be the only logical way out.
Microsoft - Where would you like to go today, Maybe Jail?
I believe that you are mistaken. There are many people still living who remember it and you can buy video tape copies of the show. This seams a little much for "an urban myth"
-- MarkusQ
I fail to see how you conclude that I am only "partly right" when the link you posted mentions the existence of the very TV show that you initially claimed was "an urban legend". If you recall, nobody said that there wasn't a $64 question on the radio first; but I do claim that the existance of the radio show doesn't magically make the TV "an urban legend".
-- MarkusQ
$7995 single / $14995 dual
Check the prices yourself:
http://www.hp.com/workstations/products/itanium
link
I know that he said that, but perhaps he didn't see the the PPC roadmap on Motorolas website recently. The G5 is 64-bit and is 32-bit backwards compatable.
That's not true. There will be a 64-bit version with 32-bit backwards compatibility and a 32-bit version (just like with the PowerPC 620 vs 601). That is what it says on the roadmap. Since programmers are still transitioning to OS X, I wouldn't expect the switch soon, at least not until the high-end users start complaining about a lack of RAM. Don't forget, 64-bit will hardly make a difference in speed for most uses, especially since the G4 already has a 128-bit processing unit (Altivec). Any application that would benefit greatly from 64-bit instructions already supports Altivec. On the other hand, 64-bit instructions/data means moving twice as much data, even for 32-bit instructions. Given that modern CPU's are for a good part limited by bandwith issues, this may make a 64-bit CPU slower than the 32-bit version.
The larger registers and caches will increase the size of the die and thus the cost of the chip. So I'm not looking forward to it yet, my next computer will probably not (need to) move beyond 2GB of RAM, so I can wait.
The Drowned and the Saved - Primo Levi
For much more information on ia-64 and McKinley, see the HP cpus website at http://cpus.hp.com under technical references.