Phoronix checks out the multi-core performance of AMD's new Bulldozer architecture in Linux, you can check out the results over here. The site concludes the AMD FX-8150 doesn't scale as well as a true eight-core configurations (i.e. dual quad-core Opterons) but for most multi-core workloads the chip is quite competitive.
"There has been a lot of discussion in the past two weeks
concerning AMD's new FX-Series processors and the Bulldozer
architecture. In particular, with the Bulldozer architecture consisting
of "modules" in which each has two x86 engines, but share much of the
rest of the processing pipeline with their sibling engine; as such, the
AMD FX-8150 eight-core CPU only has four modules. In this article is a
look at how well the Bulldozer multi-core performance scales when
toggling these different modules. The multi-core scaling performance is
compared to AMD's Shanghai, Intel's Gulftown and Sandy Bridge processors."