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> As for why AMD is going for this route, rather than trying to beat Intel in per clock efficiency? Well, because clock speeds are something they can improve n

by Freaky 13y ago

> As for why AMD is going for this route, rather than trying to beat Intel in per clock efficiency? Well, because clock speeds are something they can improve now, and not in $n years time when their next major microarchitecture is ready. Intel had the exact same problem with the Pentium 4, and they were similarly stuck with minor tweaks and desperately increasing clock rates for years before Core was ready.

Lagged2Death 13y ago
I wish I had a cite for this. It was my understanding that P-IV was originally conceived as an architecture that could be clocked up and up for years to come. Developing a new architecture is expensive and risky (see P-IV, Itanium), so the hope was to design something that would scale up so well as manufacturing improved that a few generations of architectures could be skipped, so to speak. They had hoped the P-IV would eventually reach 10GHz or so. Which made it OK that P-IV retried fewer instructions per clock than the P-III that came before. Scaling up like that isn't such a radical idea; the P6/i686 architecture behind the Pentium Pro, Pentium II and Pentium III had spanned a spectrum from 150MHz to 1.4GHz, after all, nearly an order of magnitude. But it turned out that somewhere between 3 and 4 GHz, things got really difficult. "Minor tweaks and desperately increasing clock rates" was more or less the P-IV plan from the get go. It just turned out not to work.
- yk 13y ago
  Anandtech discussed this in their Bulldozer review: AMD's architects called this pursuit a low gate count per pipeline stage design. By reducing the number of gates per pipeline stage, you reduce the time spent in each stage and can increase the overall frequency of the processor. If this sounds familiar, it's because Intel used similar logic in the creation of the Pentium 4. http://www.anandtech.com/show/4955/the-bulldozer-review-amd-fx8150-tested/3 http://www.anandtech.com/show/4955/the-bulldozer-review-amd-... And since I read this, I really wondered what trick AMD has up its sleeves.
  - VladRussian2 13y ago
    there is no trick, just desperate attempts to survive. 10 years ago AMD had more efficient architecture, Intel - more GHz (remember 2.2 Athlons having 3700 "PR-rating"?). Intel's approach was commercially more successful - customers were still buying GHz, and AMD was trying to educate market about real performance while radiating impression of a looser who just can't get good process and fabs. AMD gave up and decided to pursue P4-like approach for their new architecture, while Intel hit GHz "sound barrier" and went efficiency way by resurrecting PIII style architecture which resulted in Core CPUs. AMD made a huge, strategic mistake 10 years ago. How the execs in charge of Bulldozer have been BS-ing their way inside AMD last 5 years - that is a typical everyday miracle of a big company internal life.
    - tacticus 13y ago
      There is also the billions intel spent making sure dell and hp and co. would never buy AMD
      - zanny 13y ago
        I actually take notice of how many consumer laptops I see in a walmart / target / best buy are actually running AMD APUs. The big brands might not, but they see bigger numbers on the A6 than a Pentium and feel better about the buy even if the Pentium dominates it.
        AnthonyMouse 13y ago
        The trouble is that most computers aren't bought at Best Buy or Walmart, and the ones that are tend to be the low end garbage with no margins for the hardware vendor. Keeping AMD out of Dell and HP is what kept them out of corporate America. Corporations literally buy PCs by the pallet, and then they pass on the volume discount to employees who want to buy one for home.
        csense 13y ago
        > they pass on the volume discount to employees who want to buy one for home Really? I don't see the use case for ordering a PC this way for the home. When I'm buying a home PC, or recommending one for others, it's either: (a) A bottom-of-the-barrel PC. As long as it has 1GB of memory and more than one core, you can use it for web browsing, Youtube, email, and word processing. This is what non-techies usually want (but they don't know they want it and may get upsold by good marketing). This is what I want unless I'm planning on running a specific application that requires more. (b) A powerful PC for gaming. It needs a decent discrete GPU if it's going to play current games. Most office PC's don't have one, unless you work for Pixar. AFAIK the machines purchased by corporations for general office use are usually middle-of-the-road beasts that cost more than category (a) but don't have the discrete GPU of category (b). I'd be guessing they'd be a waste of money for home use, even after the volume discount.

by Freaky 13y ago

Lagged2Death 13y ago

I wish I had a cite for this. It was my understanding that P-IV was originally conceived as an architecture that could be clocked up and up for years to come. Developing a new architecture is expensive and risky (see P-IV, Itanium), so the hope was to design something that would scale up so well as manufacturing improved that a few generations of architectures could be skipped, so to speak. They had hoped the P-IV would eventually reach 10GHz or so. Which made it OK that P-IV retried fewer instructions per clock than the P-III that came before. Scaling up like that isn't such a radical idea; the P6/i686 architecture behind the Pentium Pro, Pentium II and Pentium III had spanned a spectrum from 150MHz to 1.4GHz, after all, nearly an order of magnitude. But it turned out that somewhere between 3 and 4 GHz, things got really difficult. "Minor tweaks and desperately increasing clock rates" was more or less the P-IV plan from the get go. It just turned out not to work.

yk 13y ago
Anandtech discussed this in their Bulldozer review: AMD's architects called this pursuit a low gate count per pipeline stage design. By reducing the number of gates per pipeline stage, you reduce the time spent in each stage and can increase the overall frequency of the processor. If this sounds familiar, it's because Intel used similar logic in the creation of the Pentium 4. http://www.anandtech.com/show/4955/the-bulldozer-review-amd-fx8150-tested/3 http://www.anandtech.com/show/4955/the-bulldozer-review-amd-... And since I read this, I really wondered what trick AMD has up its sleeves.
- VladRussian2 13y ago
  there is no trick, just desperate attempts to survive. 10 years ago AMD had more efficient architecture, Intel - more GHz (remember 2.2 Athlons having 3700 "PR-rating"?). Intel's approach was commercially more successful - customers were still buying GHz, and AMD was trying to educate market about real performance while radiating impression of a looser who just can't get good process and fabs. AMD gave up and decided to pursue P4-like approach for their new architecture, while Intel hit GHz "sound barrier" and went efficiency way by resurrecting PIII style architecture which resulted in Core CPUs. AMD made a huge, strategic mistake 10 years ago. How the execs in charge of Bulldozer have been BS-ing their way inside AMD last 5 years - that is a typical everyday miracle of a big company internal life.
  - tacticus 13y ago
    There is also the billions intel spent making sure dell and hp and co. would never buy AMD
    - zanny 13y ago
      I actually take notice of how many consumer laptops I see in a walmart / target / best buy are actually running AMD APUs. The big brands might not, but they see bigger numbers on the A6 than a Pentium and feel better about the buy even if the Pentium dominates it.
      - AnthonyMouse 13y ago
        The trouble is that most computers aren't bought at Best Buy or Walmart, and the ones that are tend to be the low end garbage with no margins for the hardware vendor. Keeping AMD out of Dell and HP is what kept them out of corporate America. Corporations literally buy PCs by the pallet, and then they pass on the volume discount to employees who want to buy one for home.
        csense 13y ago
        > they pass on the volume discount to employees who want to buy one for home Really? I don't see the use case for ordering a PC this way for the home. When I'm buying a home PC, or recommending one for others, it's either: (a) A bottom-of-the-barrel PC. As long as it has 1GB of memory and more than one core, you can use it for web browsing, Youtube, email, and word processing. This is what non-techies usually want (but they don't know they want it and may get upsold by good marketing). This is what I want unless I'm planning on running a specific application that requires more. (b) A powerful PC for gaming. It needs a decent discrete GPU if it's going to play current games. Most office PC's don't have one, unless you work for Pixar. AFAIK the machines purchased by corporations for general office use are usually middle-of-the-road beasts that cost more than category (a) but don't have the discrete GPU of category (b). I'd be guessing they'd be a waste of money for home use, even after the volume discount.