AMD's Bobcat and Bulldozer

[terrace215]

This is exact the thing people like terrace hang on, that BD cores loose 5-10% compared to Thuban. That is just naive to believe.

It's -5% IPC vs Thuban, then higher frequency due to the longer pipeline with faster pipe stages, estimated at 20-25%. This is for a single thread doing integer work.

So says AMD's ex Chief Architect.

IPC is not "performance" it is "performance/frequency". I believe this is the source of much confusion.

BD will have slightly LOWER (integer) IPC for single threads than Phenom-II, which it will attempt to (more than) make up for using speed-racer frequencies. Put together, you could see a performance increase of 15-20% (this depends on GloFo being able to deliver a good enough gate-first 32nm process, which is... uncertain) , but this is nowhere near enough to catch SB, as it just demonstrated a similar gain over Nehalem/Westmere, and Phenom-2 starts in a big hole relative to Nehalem. This is about integer single- (and therefore also low-) threaded workloads.