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Re: AMD Bulldozer released... and it sucks

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Dan wrote:
> 1. The cache hierarchy is not good
>
> Each module has a 64KB 2-way set associative I-cache, two 16KB 4-way
> set-associative write-through D-caches, and 2MB L2. 16KB L1 is a
> significant step below the previous 64KB L1D caches in K10. Not only
> that, but the L2 cache has a horrible 21-27 cycle access latency. I'm

16K L1 + ~24 cycles to L2???

That is simply broken, I can't think of a single program which would 
have that as a "sweet spot". :-(

> very interested as to what set of applications this hierarchy is
> optimized for, since it's very different than anything else on the
> market. Given the current state of BD performance, could it be that
> their simulations that led to their cache hierarchy design were
> inaccurate?
>
> 2. Switching from full custom to automatic synthesis caused them to
> miss clock frequency goals
>
> Current rumors state that AMD switched from their usual full custom
> chip design to a more SoC-like design process (which apparently caused
> a mass exodus of ex-DEC engineers) . Doing so costed them 20% in power/
> perf/area. I was under the impression though that the latest shrinks
> of K10 were also synthesized instead of full custom, but what do I
> know. The BD die shots don't really look like the chip was fully
> synthesized (unlike Bobcat, which is obviously fully synthesized), so
> I dunno.
>
> 3. The Global Foundries 32nm process sucks
>
> This still doesn't explain why a 2 billion transistor architecture is
> worse than the Sandy Bridge 1 billion transistor architecture.

Bulldozer will have to compete against Ivy Bridge as well, and that 
bridge is significantly better than the Sandy one...

Terje

-- 
- <Terje.Mathisen at tmsw.no>
"almost all programming can be viewed as an exercise in caching"

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Thread

AMD Bulldozer released... and it sucks Dan <dzhang1@gmail.com> - 2011-10-12 20:59 -0700
  Re: AMD Bulldozer released... and it sucks "Paul A. Clayton" <paaronclayton@gmail.com> - 2011-10-12 23:49 -0700
    Re: AMD Bulldozer released... and it sucks "Paul A. Clayton" <paaronclayton@gmail.com> - 2011-10-14 10:45 -0700
  Re: AMD Bulldozer released... and it sucks Terje Mathisen <"terje.mathisen at tmsw.no"> - 2011-10-13 09:06 +0200
  Re: AMD Bulldozer released... and it sucks MitchAlsup <MitchAlsup@aol.com> - 2011-10-13 10:54 -0700
  Re: AMD Bulldozer released... and it sucks "Andy \"Krazy\" Glew" <andy@SPAM.comp-arch.net> - 2011-10-13 11:05 -0700

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