Where does 64-bit help?

Although the performance that will sell the Athlon 64 today has nothing to do with this, the 64-bit part of the equation will definitely play a role in the processor's future. With no final release of the 64-bit version of Windows XP, there is no popular OS support (we will touch on Linux support as well as Win64 support shortly) and no real application support at this time, but where will the 64-bitness of the Athlon 64 help?

There are three main categories that you can split up the performance benefits into: 32-bit applications running on a 32-bit OS, 32-bit applications on a 64-bit OS and 64-bit applications on a 64-bit OS; we will be analyzing each one of these scenarios individually.

Case 1: 32-bit apps under a 32-bit OS

At the launch of the Athlon 64, the predominant operating environment will be running 32-bit applications under a 32-bit OS. All performance benefits the K8 architecture will show here are courtesy of the on-die memory controller, improved branch predictor, higher clock speed and more robust TLBs - none of the performance improvements you'll see in this case will have anything to do with the 64-bit capabilities of the processor.

Case 2: 32-bit apps under a 64-bit OS

When Windows XP 64-bit Edition is officially released (a public beta is due out at the time of publication), many users will be running their 32-bit applications under the 64-bit OS.

Outside of the performance improvements that we just outlined in Case 1, there are a couple of additional benefits the Athlon 64 may offer users. Currently under Windows, although you have a physical memory limit of 4GB, any given process can only use up to 2GB of memory; the remaining 2GB is reserved for use by the OS. With the 32-bit applications under a 64-bit OS scenario, each 32-bit application could be given a full 4GB of memory to work with, instead of being limited to the 2GB Windows process size limitation. Unfortunately this benefit isn't really "plug 'n play" as the application would have to be aware that it can use the added memory, which in the vast majority of cases would require a new patch to be made available.

The second benefit the Athlon 64 could offer in this scenario comes from the availability of additional registers. Although the 32-bit application would still only be compiled to use the regular set of 8 general purpose registers and standard set of FP and SSE2 registers, the 64-bit OS would be able to reference and use all of the registers at its disposal. The performance benefits that you would see here exist in any sort of task handling that the OS would be doing (switching between applications) as well as just regular Windows performance. Granted that the performance improvements seen here should be negligible, considering the extra overhead that does exist when running 32-bit applications in a 64-bit environment (more on this in a bit).

Case 3: 64-bit applications under a 64-bit OS

The final scenario is the one that shows the most promise, yet has the least amount of application support today - running a 64-bit app under a 64-bit OS. Here, the benefits are numerous; not only do you get the performance improvements courtesy of the Athlon 64's architecture, but each application now has full access to the increased number of registers and each application can use much more than 4GB of memory.

Although the Athlon 64 can support 64-bit memory addressability, for demand reasons it only supports 40-bit of physically addressable memory - or ~137GB, not exactly a limiting factor at this point.

The performance improvements developers are expecting to see under this final scenario has been estimated to be in the 10 - 20% range in tasks that are not memory bound, meaning those areas where the application is using less than 2 - 4GB of memory in the first place will still see sizable performance gains courtesy of the availability of more registers. We will investigate a few of these scenarios to substantiate (or refute) these claims later on in the article.

Performance improvements where you are memory bound will be even more impressive; just think about how slow swapping to disk is and how much faster keeping everything in memory makes your computer.

An Early Christmas present from AMD: More Registers AMD's Gem: Athlon 64
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  • Anonymous User - Monday, September 29, 2003 - link

    Where can I buy the P4 Extreme Edition ? Anand says it will be available in a month or two. Many websites say that it will be available in the Q1 ' 04.

    Anand , why the hell you included P4 Emergency Edition in your review , when it is not available for purchase ? Nor is it clear when will it be available for purchase ?

    Athlon64 3200+ and FX-51 ARE available for purchase. So it does not make sense to do a comparision with YET NOT Available P4 Emergency Edition.

  • Anonymous User - Monday, September 29, 2003 - link

  • Anonymous User - Monday, September 29, 2003 - link

    #102 - that's eight quarters of losses in a row and this quarter just about to end will make 9. It is projected that AMD will not be back into the black until at least Q4 2004 - but that was before they bought into that Flash business that is also losing money.
  • Anonymous User - Sunday, September 28, 2003 - link

    #102...I don't see AMD laughing all the way to the bank any time soon. Last time I checked they lost money for over a year and a half. Thats 6 quarters in a row of losing money! Translation: If they don't stop giving away tons of performance for nothing, they'll die (2500+ Bartons for $85?? Sheesh). If you think prices are high now, wait till AMD dies. Tell me what you think of prices then :)
  • Anonymous User - Sunday, September 28, 2003 - link

    It's almost comic to see people saying prescott is that good. It won't be cranking up the speed as the P4 did. It's already at 104watts of heat. There "PLANNED" fix is only to get it to 95 watts at launch. To crank this cpu up at all is going to require water cooling. Jeez, AthlonFX is only running around 60watts. Translation easy to jack up the clock whenever the process gets the kinks worked out. The biggest issue is ALREADY solved (heat). Intel has a long way to go (look at the roadmap, not many releases for Prescott in '04). AMD should have NO trouble keeping up and topping them in my book if desired. AMD has taken the lead and won't likely give it back for a while (save the stupid INTEL benchmarks by bapco and their other shill ZD). Check all review sites but anandtech and toms, take a trip to www.aceshardware.com for 15 games, 11 of which are victories for athlon, many by LARGE MARGINS, up to 43% faster in age of mythology! Two of the P4EE victories were 1% (margin of error that is). Look at how many are double digit victories for AthlonFX (again, this is against a chip that won't be available for 2 months at best).

    Lets also not forget that AMD is in the drivers seat now with 64bit. Intel is USING AMD's instruction set! Intel is now in AMD's old boat. You will never be FASTER than the guy that wrote the actual instructions, when you are trying to reverse engineer them, emulate them and get them to work. How is Intel going to cheat with 64bit now, when AMD has control of the instruction set? There won't be an SSE2 cheat in the next batch of cheater benchmarks (you can't leave out AMD's 64bit instructions as the pricks did with sse2 this time).

    I can't even believe that Anand did NOT turn on SSE/SSE2 in AthlonFX. Claiming he doesn't like to change benchmarks. Newsflash moron: Turning on the chips SSE does NOT change the benchmark. It merely recognizes the chip. Isn't this the FIRST thing you would do if you bought this chip? Go get a free download FROM microsoft that fixes their "ID INTEL ONLY" bug? Don't forget you SAID back in an old athlon article where you DID use this patch, that you would ONLY use it in the future if it was PUBLICLY released (and not a patch amd was just handing out to reviewers). Well, it's PUBLICLY released, and NOT by AMD. Microsoft officially supports this patch, which BTW doesn't change ONE BIT of scripting in the benchmark. It merely tells the benchmark, "hey, I've got SSE also, turn it on cheaters!". Look at the scores here:
    http://www.sudhian.com/showdocs.cfm?aid=434&pi...

    Patched scores 64.3, while unpatched scores 52. NOTE: this only turns on SSE in ONE app included in this benchmark. Windows Media Encoder. I've got one question for bapco. Why does media encoder count for so much in their silly benchmark? AMD gains 20% in this ENTIRE benchmark just by turning on SSE in WME? WTF? More cheating.

    One question for Anandtech: Why are you using such a cheating benchmark? What happened to CSA Research's benchmark that you loved until Intel told you stop using it? Don't forget INTEL hired the guy to write that benchmark. They just didn't like his results so fired him...LOL. When you tell the truth Intel gets pissed. If you're going to use this benchmark, do what ALL public users will do and turn on SSE. You said you'd use it if it was PUBLICLY available (this was in regards to last years version, but your statement should still hold true). AMD is no longer handing out patches to reviewers. MICROSOFT IS! Also silly in Anands benches is the use of lightwave after its already included in ZD's benchmarks. Where is the lightwave SUNSET benchmarks? Oh that's right, Intel didn't write that one, and they told you to use the other ones (held a meeting on sept8th just to get that straight, what you should use and should NOT use...Looks like anand was listening to Intel). Look at the studiomax benches elsewhere. Check Aceshardware again, for the STUDIO PC benchmark for 3dstudiomax. Daily use, by a company that USES the software, instead of a special written script from Intel. Hmm...AMD wins? Check out REAL TIME RAYRACING at aces. Hmm, amd wins? Mojo world, hmm...AMD wins? Looks like we better rethink this "workstation and rendering is better on Intel" crap eh? Check out Cinebench 2003's Cinema 4D benchmarks here:
    http://www.tech-report.com/reviews/2003q3/athlon64...

    Look at those shading scores...Hmm, AMD wins in some cinema 4D benchmarks? Well, I guess there's a DIFFERENT side to the coin for all of anands claimed P4 victories in RENDERING. You should stop making blanket statements when you run so few rendering benchmarks (and all Intel's favorites at that, favorite scripts that is, with favorite filters). Clearly it depends on WHAT you are doing, as to WHO is the fastest chip for X rendering job eh?

    Telling people to NOT buy AthlonFX is stupid too. What are you suggesting they buy then? A P4 that is a DEAD END SOCKET? Isn't this the same as AthlonFX51? Which AMD has said they will produce through end of 2004 (but that remains to be seen, I'd think they will make something else work in the boards first in 939 or something). It's the fastest chip on the block, but you shouldn't buy it. Cool, what should I buy right now?...ROFL.

    AMD has totally lost their credibility? WTF? When did that happen? I'm a reseller and I must have missed this I guess? They can't get it back? I wasn't aware they lost credibility in the first place. How much did Intel pay you to say this crap? Did AMD chips suddenly get incompatible, or all die at once last week and I didn't hear about it? Don't complain about price either. If a chip CLEARLY smokes the competition, why should the winning company give the chips away at rock bottom prices? More BS. AMD had to price low when compatibility was an issue, and speed was an issue in some cases. Neither of these are issues today. They win in the majority of benchmarks (especially gaming!), they should charge accordingly. Markets set prices, companies don't. If they fly off the shelves at the current price, then its a price the market can bare isn't it? IF they sit on the shelf, clearly AMD will lower them. But I fail to see why you should lower your prices until the market tells you it won't pay what you're asking for the chip. Never heard of supply and demand eh? I price everything I sell, at whatever the top dollar is that I feel I can get. And adjust as needed after that. No business does any different. No business purposely low-balls themselves until FORCED to by market conditions. If AMD wasn't here, Intel would be still charging us $1000 for a top end cpu, and you'd still be telling us to buy them if we want the best chip on the block. Why is AMD different? AMD clearly wins, sells the chip at a relative price, (P4EE will be priced slightly HIGHER mind you and still loses) and you complain and say don't buy it? What's the excuse for the double standard? You've slowly joined tomshardware on the Intel side (I can't even believe tom's said ID Software makes Unreal Tourney and it isn't optimized for AthlonFX"...LOL. Uh, Epic makes it fool, and its was the first game announced FOR athlon64...ROFL. Why are you still using Quake3 (which toms still loves too...LOL)? This benchnmark is 3+yrs old! No CURRENT Q3 based benchmark shows a 50+fps lead for Intel. Nobody I know even plays Q3 today. Why use it? Where are the wolfenstein, or jedi2 benches (much more relevant if you're going to use a Q3 based game at all)? Why would you use a 3yr old benchmark when there are clearly more relevant benchmarks USING THE SAME ENGINE available to show todays performance? Was this just to slight AMD, because of their CLEAR victory in Unreal 2003, when showing botmatch? Which is where all games will lean AMD's way. If you are going online, prepare to have a slower gaming experience when a lot of people get in the game, no matter what game you're playing. TRUE CPU power kicks in then, and there are no tricks to pull to save you. Q3 just likes bandwidth, which is not an issue when online. CPU power is an issue online. When in a single player game the cpu is not your problem (at most you are calculating for 3 or 4 enemies on your screen and nothing happening elsewhere in the game). Online it IS your problem, as you calculate for everyone everywhere. Hence the stomping Intel receives in botmatch. This is also the case in strategy games and sims (racing etc), where calc's are made for TONS of units or a lot of AI. Same story, Intel gets killed. Hence the story with Age of mythology, Grand Prix4, Battlefield 1492, wolf enemy territory (hey isn't this a Q3 based game?..AMD kicks Intel A$$ in it! Oops, thats right, we should only be benching the 3yr old versions..Nobody plays WolF enemy territory, battlefield etc...Who plays new games? We all want those old benchmarks..LOL) and Medieval at aceshardware. The only one I can't figure out is Civ3. Hmm. With all that though, remember, you shouldn't buy this KILLER CPU...ROFL. Bring on the Prescott chip (at 104watts I need a heater this winter in oregon...hehe).

    I digress..
  • Anonymous User - Friday, September 26, 2003 - link

    I'm also no fanboy (isnt it sad that on forums you have to start making your point by making sure everyone understands that you are not a fanboy?), but to be honest I don't think that Intel was ever truly leading in terms of CPUs. They did have the "performance crown" for the past few months, but AMD is still much better value for money. I know for a fact that I'd prefer to have a CPU thats 5% slower if it means I save myself enough money to have a twice as fast graphics card :)

    Besdides, the times before the 2800+ were just taking the piss, as AMD CPUs were botrh cheaper AND faster :)
  • Anonymous User - Friday, September 26, 2003 - link

    Dudes, u gotta be kidding me.. isnt it obvious that Intel is winning and that AMD is just catching up. Im no Intel or AMD fanboy, i like good competition cause it makes better/cheaper products for me...=-).. AMD has just made a proc that can keep up with the P4 and beat it in some applications but Intel is already planning past the p4 and AMD has just caught up.. This is AMD's best VS. Intels old.. I think AMD will be behind a few months once again.
  • Anonymous User - Friday, September 26, 2003 - link

    The German TomsHardWare site has just revised its Athlon 64 review as they found they wer ebeing fooled by Intel as a marketing trick... I'm sure Tomshardware.com will be updated soon with the same info.

    Basically the P4 EE isnt available until christmas or springtime which essentially makes any comparrison with the Athlon 64 or FX completely useless. The Athlon is available NOW, Intels chip is still 60-90 days away...
  • Anonymous User - Friday, September 26, 2003 - link

  • Anonymous User - Thursday, September 25, 2003 - link

    AMDs chip seems to offer an incremental improvement in performance (like Intels offering). All this hype for products which offer moderate to good improvements in speed? Pretty anti-climactic. Let's have some real innovation here...something that actually increases the usefullness of a computer, not just ticking benchmarks up to the next level and claiming it's a revolution. Users with no sense of the value of money eat the marketing up and blow hundreds of dollars on the latest cpu while these companies laugh all the way to the bank.

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