The Quest for More Processing Power, Part Three: "Multi core of Intel and AMD compared"
by Johan De Gelas on May 18, 2005 3:15 PM EST- Posted in
- CPUs
Introduction
The Pentium-D dual core Pentium 4 and Opteron 875 dual core are launched. At the end of 2007, a quad core Whitefield CPU will be launched by Intel, and a quad core “K9” of AMD will make a stand against Whitefield. The multi core train has picked up speed and is unstoppable. But what will be the challenges ahead? What are the architectural advantages of the current cores? What will set the different architectures apart? Read on in this third part of The Quest for More Processing Power series.In case you missed it, in our first article, we explained that dynamic power, power leakage, the memory wall and wire delay have forced CPU designers to rethink the methods that they use to achieve higher performance CPUs.
In Part 2, Tim Sweeney, the leading developer behind the Unreal 3 engine, explained the challenges of multi-threaded development of the next generation of games.
The multi-core future...
In the past 15 years, architectural improvements have made sure that the Pentium 4 issues and retires about 6 times more integer instructions each clock cycle than an Intel 486 could on average. At the same time, the die size would have been 15 times bigger if there were no advancements in silicon process technology, and even those aggressive advancements could not avoid the fact that the Pentium 4 needs almost 20 times as much power.Clock speed increased from 33 MHz to 3800 MHz, so it is clear that clock speed, not extracting more ILP (Instruction Level Parallelism), has been the main reason why a Pentium 4 performs so much better than an i486.
However, the next generation of CPUs will be based on a completely different philosophy. The Xeon MP Version 2007, alias Whitefield, will have 4 cores, and run at speeds at around 2.6 GHz. At that speed, there are reports that it would consume less than 90 Watt. Intel will use its P-m “know-how” to keep the power dissipation so low. Each core is not really a P-m, but it is clear that the pipeline will be shorter than the one of Willamette, the first implementation of the Pentium 4’s Netburst architecture.
AMD’s K9 seems to be a slightly different beast. Andreas Stiller of C’t reported that this Quad core CPU monster would have a TDP of 140 Watt, and run at about 3 GHz.
So, it seems that clock speed will no longer drive performance, but higher IPC and more cores will.
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nserra - Thursday, May 19, 2005 - link
The previous post was for the biased person who wrote this article. Johan De Gelas^
|Just kiding ;)
nserra - Thursday, May 19, 2005 - link
"AMDs current dual core architecture is vastly superior to Intels"This is wrong!!! You said your self that Intel "new" processor was more of a “special” packing than a dual core processor, so you should say is:
"AMDs current dual core architecture is amazing let’s wait what intel will do at a latter time"
TDP is for power consuming as a 500W PSU is at it. Just because you have 500W PSU doesn’t mean it draws 500W of power.
New Venice core as more transistors than the previous core not just because of SSE3, there is new power stages than can be enable to further lower power consuming, I doubt that putting a Turion on a regular board will enable those new power stages.
Viditor - Thursday, May 19, 2005 - link
G'day Jarred!"the Pentium M 2.0 GHz chips manage to run at 22W"
To be specific, they have a TDP of 22 watts which isn't really the same thing...
"as I understand it even under maximum load the Pentium M stays under 22W, right?"
Not at all...in fact it can be significantly higher than that. Intel's TDP measures an average usage under load rather than peak, while AMD's measures absolute theoretical peak under the worst conditions. This is why the TDP is quite meaningless...
I guess my point is that I am of the opinion that the Turion might actually run at significantly lower power usages. As absolutely nobody (that I am aware of) has tested beyond the system level (i.e. the chip itself), I can't be sure...but judging by the actual specs of the chips themselves (not the TDP, but the electrical specifications) it appears that the PM may indeed be higher.
I know I've asked before, but with the power usage and heat becoming more and more important, couldn't you guys develop a test of the actual realworld usage of the chips themselves?
I think it might be quite illuminating...
Cheers!
4lpha0ne - Thursday, May 19, 2005 - link
@Questar:Criticizing Intel and saying good things about AMD and IBM means, that Johan is an AMD fanboy? I think not. You'll see, that the opinions about Whitefield, Merom, Yonah & Co. after hitting the public will be better than about Smithfield now. That's simply the result of the amount of effort put into the designs. A dedicated dual core design is not the same as an on die dual Xeon system.
@photoguy99:
I'd say, Johan can make this conclusion, because he has the knowledge to do so. I'd come to the same conclusion, since the Windows scheduler (at least for XP) is not so much core-aware. It just sees the logical or phyisical CPUs and if one becomes free, it just sends the next thread to it. This causes thread-hopping (can be seen in the tech-report dual core reviews thanks to task manager screenshots). In such cases it matters somewhat if the last used data is in the other L2 cache and can be quickly transferred to the current L2 cache. And it matters for multithreaded applications, which work on the same set of data.
@mazuz:
I'd suggest to look at benchmarks of a 275 vs. dual 248 with 1 dual channel memory bank and benchmarks of a dual Xeon with FSB800 and a similarly configured (cache, FSB, memory, HT) Smithfield. That's the difference caused by the SRQ-connection.
@Ahkorishaan:
The mentioned upcoming Intel cores will indeed be nice. But some people here and on many other forums sound like the dual core K8 was AMD's last CPU and the K8 their last core ever. :) However, have a look at AMD's patent portfolio and you'll see, that this is not the case. As Fred Weber said, AMD is also still looking at power consumption. This is maybe the reason, why we might see a future CPU with more cores, but less FPU power per core (due to shared FPUs).
AMD is also working on using things like clock gating and throttling (used by P-M) to further reduce power consumption. Currently they only implemented some standard features to keep power consumption down like other transistor designs (especially slower transistors in not so critical places), microarchitectural changes (better HALT mode), C3 state and PowerNow!/C'n'Q.
Matthias
JarredWalton - Wednesday, May 18, 2005 - link
Viditor, I think the point is that the Pentium M 2.0 GHz chips manage to run at 22W - still less than 1/3 of what the Winchester and Venice cores put out, I think. What exactly did they do to get that low? Well, there's gating technology for sure - i.e. power down unused portions of the chip - but as I understand it even under maximum load the Pentium M stays under 22W, right?Maybe Johan has more specifics, but I don't. I just know the price for power use on the design is very impressive, and I was surprised some of the same tech wasn't used in Prescott.
Viditor - Wednesday, May 18, 2005 - link
Your usual excellent work Johan, thanks.A couple of nits to pick...
"Intel will use its P-m “know-how” to keep the power dissipation so low"
If you could qualify exactly what "know-how" you mean, that would be appreciated. IMHO, a major reason that PM is able to stay so much cooler that the Netburst chips (and on par with the Athlons) is that it doesn't have nearly as many features... Is there a reason you see the PM translating well into full blown server and desktop chips?
"Intel can leverage their experience with the power saving features of the P-m to design quad core CPUs with remarkably low TDP"
Arrrrrggghhh! This is a pet peave of mine. TDP IS NOT POWER USAGE!!! Sorry, I know you know this, but most don't and it's been quite frustrating.
For those who don't know, TDP is an arbitrary design spec for OEMs to use with the CPU...
AMD's TDP is so much higher than Intel's relative to actual power usage because AMD is much more cautious in it's design spec, not because it uses that much power.
As to Questar's comments, IMHO the fact that the worst thing he can say is a short unsubstantiated rant speaks volumes to the credibility of the article.
Thanks again Johan!
phaxmohdem - Wednesday, May 18, 2005 - link
You are all fools. IDT's Winchip X2 dual core solution will blow all of this crapolla out of the warer.mazuz - Wednesday, May 18, 2005 - link
"AMDs current dual core architecture is vastly superior to Intels"This seems like a pretty strong statement considering there doesn't seem to be any known real world advantage to this architecture.
photoguy99 - Wednesday, May 18, 2005 - link
Johan, isn't this statement a little unfounded:"we can be pretty sure that there are applications out there that do benefit from very fast cache-to-cache transfers"
How can you be pretty sure when you've cited none? I know you said you'll do more testing - but *after* that testing is done seems like the time to be "pretty sure" it's a real world benefit.
You've written a good article, it was informative. Just prefer conservative research conclusions.
bob661 - Wednesday, May 18, 2005 - link
#7Who cares which company is ahead or behind? I sure as hell don't. Give me good bang for the buck. That's all I want.