Comparing AMD to Intel

[wseyller]

I just wondering how an AMD cpu with lower clock speed performs similiar to an Intel cpu with higher clock speed. For example an Athlon XP 3200+ running at 2.2ghz compared to an Intel 2.8ghz or 3.0ghz. I understand some about fsb speeds and such but i'm unclear about this concept.

 

[rogue1979]

The core designs are different.

The P4 has a long pipeline to allow very high clock speeds.

The AMD is not capable of those high speeds but does more work per clock cycle.

The cpu at the speed you are running is faster than any stock speed Pentium 4 cpu available. Only an Intel overclocker with the Extreme Edition or a very fast Northwood at 3.6GHz+ can compare.

 

[thelanx]

2.2 would probably compare to a p4 3.0C I think. AMD got a little carried away with their PR naming scheme. XP 3200+ would be ~ 2.8C and I think 2.2 ~3.0C or 3.2C. For some more information, look at this thread : here

 

[rogue1979]

Originally posted by: thelanx
2.2 would probably compare to a p4 3.0C I think. AMD got a little carried away with their PR naming scheme. XP 3200+ would be ~ 2.8C and I think 2.2 ~3.0C or 3.2C. For some more information, look at this thread : here

That works for a Barton maybe, but according to his signature he has an Athlon64.

 

[Shimmishim]

i think it's very difficult to compare the two...

🙂

 

[Adn4n]

My 3200+ is in no way comparable to my collegue's 2.8 with almost similar systems.

Meaning the Athlon 64 is better.

 

[Yanagi]

Im gonna go with what I tried to explain to another guy in a previous topic. Its called Yanagis McDonalds Analogy.

to put it short. imagine you're going through the drive through on McDOnalds. where you place your order, pay and pick up the food. thats three steps.

If we now look at the intel McDonalds you have 21 different stations. Whereas you have to go through 21 different steps to get your food. to get to the end you have to travel faster to complete all the steps in the same time as the amd route where you only have to complete 12 steps in order to get your food

And elkinm further elaborated the analogy which you can read here:

I really like Yanagi's McDonalds analogy. In a CPU architecture you need to complete every stage of a pipeline in a single clock or you lose it so going back to McDonalds:

You order a sandwich, the order is sent in, someone puts a burger in the oven, when done he gives it to the nest guy who ads the ketchup, then next is the mustard, and then the bun pickles onions ect. And then you have the fries.

The slowest part is the cooking of the burger so a single clock cannot be faster then the time it takes to cook the burger or it wouldn't finish.

What Intel does is spit it up some more like cook the burger on one side, then cook on the other. Since it takes less time to cook only one side, the single clock is shorter allowing for higher frequencies but now you need two clocks to cook the burger.

Then you have other optimizations to have maximum work done in a clock like one can add ketchup, mustard and pickles in the time to cook a burger so that can be just one stage. And the problem with a mispredict is when you guess the person wants mustard when he does not so you have to thro it out and start again.

I hope that clears things up for ya a bit. I know its hard to understand but I really did try to put it as straightforward as I could. And elkinm did a pretty good job aswell. I think we deserve a sticky 😛

 

[wseyller]

Very interesting analogies. Just to say I wasn't trying to compare my amd 64 to a 2.8 or 3.0ghz intel. I know it would destroy those processors. I was using a socket A athlon xp 3200+ comparing to a 2.8 or 3.0ghz intel just as an example and was just interested in the difference in architecture between the two when it comes to determining throughput.

 

[Yanagi]

Basicly what those analogies were trying to explain. Difference is the pipelines and that AMD does more work per clockcycle. its easier to do a lot of more work on less steps than on eveb more steps..

 

[kevman]

ok in terms of 3dmark 2003 with all components ( Vide card, mem, etc)

my amd Athlon 64 3200+ (2.2GHz) and my P4 2.66@3.03 GHZ performed with two to three points of each other

EDTI: Iguess that not really that valid of a test sinces its realy GPU doing the owrk...

 

[DAPUNISHER]

Comparing AMD to Intel

Now here is a new topic for discusion.....wait, no it's not.

 

[wseyller]

Ok lets see if I can get this down. From what I know and what you guys have mentioned, with Intel's net burst technology (P4) they have pipelines that store I believe 20 step instructions basically taking larger steps and breaking them down into smaller steps which means more steps. If say step 14 failed then the pipeline has to be emptied for a new set or process has to be restarted (is this correct?). Amd uses larger fragments (correct?) means less steps. With AMD if a step failed there would be less steps in noticing the failure and a decision to make. Does this sound about right.

 

[harrkev]

You are very close. The problem is that with a 20-stage pipeline, you have 20 instructions in various stages of completion. Let's say that you encounter a conditional branch instruction (branch if some number equal to zero, for example). So that starts moving down the pipeline. What instruction should be executed next? At that point, you do NOT know the results of the branch. It could branch, or it could not branch. The exact result will be determined later. So, the processor has to guess whether to take the branch or not (whic it can do correctly about 90% of the time). If it guesses correctly, the pipeline flows smoothly.

However, if the guess is wrong, the processor has to throw out all instructions after the branch and start over.


Another food analogy: You have to cook dinner for your spouse/significant other. You can cook beef or chicken. They will only eat what they are in the mood for. So you choose to cook one (chicken for example) before they come home. If you guess right, a nice meal ready fast. If you guess wrong (whoops -- they want beef), throw the chicken out and start cooking beef.

 

[wseyller]

Originally posted by: DAPUNISHER

Comparing AMD to Intel

Now here is a new topic for discusion.....wait, no it's not.

The scope of this thread was to compare different architectures of different cpu's. It was not for flaming about what cpu manufacturer is better than the other. I'm sorry to disappoint all the people who are just dying for a thread to be started so that they could flame each other.

 

[wseyller]

ah yes branch predictive logic. Can be very fast as long as no failures occur.