mpx (mpx@nomail.pl) on 12/16/11 wrote:
>
>Bulldozer has the greatest x86 decoder ever built. So what?

Actually, bulldozer has one of the worst ones. Sure it's
fairly powerful, but it has to decode for two cores rather
than one, so you have to basically divide the power by two.

Did anybody ever figure out the logic behind sharing a
decoder for two cores? That's just crazy. It's SMT without
most of the area advantages. I bet two simpler decoders
would have been way more efficient. Backed up by the fact
that IPC has actually gone down for AMD.

Anyway, Sandybridge clearly has much more powerful decoders
in practice, and does the whole L0 I$ thing too ("microop
cache"). Now, I really hope that AMD makes a comeback, but
right now I don't think AMD has the best anything on
the CPU side.

Which is a big change. Opteron kicked arse in so many ways
back when it was competing against the P4. Superior in just
about every way possible.

(Don't get me wrong - I really like AMD, and I think Llano
is a good design for the market. And AMD clearly does have
the better GPU, although Intel has been pretty good at
keeping that "good enough" spot lately)

Linus