Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > comp.sys.intel > #135

Re: reason for AMD's Bulldozer fiasco?

Show all headers | View raw

On 01/11/2011 4:25 PM, Robert Myers wrote:
> The enormously long pipeline wasn't the only distinguishing feature of
> NetBurst.  According to someone I trust, parts of the NetBurst design
> ran at double-time.  Thus, parts of the 3GHz processors were already
> running at 6GHz, thus explaining in part the enormous power
> consumption problem that NetBurst had.  Unfortunately, not enough
> instructions would run on the faster pipeline to justify the design
> strategy, and Intel was caught between an unexpected rock and hard
> place.

I think you're referring to the P4's floating point unit which was 
optimized for SSE2, but fell behind in regular x87 floating point. 
Interestingly, the new AMD Bulldozer floating point unit is expected to 
perform best in the newer AVX or 256-bit SSE instructions, rather than 
the older 128-bit SSE instructions.

There were other doubled-speed interfaces like their FSB, which was 
running at 400MHz (eventually became 566MHz, I think), vs. AMD at 
200-266MHz, or P3 at 100-133MHz. That required the highest-speed Rambus 
or DDR memory to make good use of its bus.

> The original thought was to get a processor out with a label
> frequency in well in excess of 1GHz, leaving AMD in the dust.  Known
> performance problems would be addressed by beefing up the faster
> pipeline.  In fact, the needed transistors may well have been in the
> original NetBurst design and had to be thrown overboard because of the
> power envelope.  Intel probably knew a long time ago that the real
> problem was power management.  They just weren't as fast or as
> successful in fixing it as they thought they would be.

Which again seems to be the exact same problem that AMD will have to 
face with Bulldozer. Their next revision stepping is going to be 
entirely about getting the power consumption under control.

I think AMD's biggest problem was not that Bulldozer has low IPC (it 
does), but that AMD couldn't right away bring Bulldozer out with enough 
clock frequency to compensate for its IPC. It's now got to really start 
pushing the clock speeds out.

	Yousuf Khan

Back to comp.sys.intel | Previous | Next — Previous in thread | Find similar

Thread

reason for AMD's Bulldozer fiasco? "Orson Cart" <ex-privat@parts.org> - 2011-10-21 14:47 +0100
  Re: reason for AMD's Bulldozer fiasco? Yousuf Khan <bbbl67@spammenot.yahoo.com> - 2011-10-21 20:19 -0400
    Re: reason for AMD's Bulldozer fiasco? Robert Myers <rbmyersusa@gmail.com> - 2011-10-30 09:36 -0700
      Re: reason for AMD's Bulldozer fiasco? Yousuf Khan <bbbl67@spammenot.yahoo.com> - 2011-10-30 23:03 -0400
        Re: reason for AMD's Bulldozer fiasco? Robert Myers <rbmyersusa@gmail.com> - 2011-11-01 13:25 -0700
          Re: reason for AMD's Bulldozer fiasco? Yousuf Khan <bbbl67@spammenot.yahoo.com> - 2011-11-02 20:57 -0400

csiph-web