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Conclusion:
In looking at the two designs, it is sensible to compare a multi-threaded Sandy Bridge core to a Bulldozer module and separately consider single threaded operation as a special case. Both support two threads although the resources are very different. At a high level, Sandy Bridge shares everything between threads, whereas Bulldozer flexibly shares the front-end and floating point units, while separating the integer cores.

A Sandy Bridge core should have substantially higher performance than a Bulldozer module across the board for single threaded or lightly threaded code. It will also have an additional advantage for floating point workloads that use AVX, (e.g. numerical analysis for finance, engineering). With AVX, each Sandy Bridge core can have up to 2X the FLOP/cycle of a Bulldozer module, although they would be at parity if the code is compiled to use AMD’s FMA4 (e.g. via OpenCL). FMA4 will be relatively rare because, while elegant, it is likely to be a historical footnote for x86, supplanted by Intel’s FMA3. For software still relying on SSE, the difference between the two should be minimal. In comparison, Bulldozer will favor heavily multi-threaded software. Each module has twice the memory pipelines and slightly more resources (e.g. retirement queue/ROB entries, memory buffers) than a single Sandy Bridge core with two threads, so Bulldozer should do very well in many highly parallel integer workloads that exercise the memory pipelines.

In many ways, the strengths of Sandy Bridge reflect the intentions of the architects. Sandy Bridge is first and foremost a client microprocessor – which requires single threaded performance. Bulldozer is firmly aimed at the server market, where sacrificing single threaded performance for aggregate throughput is an acceptable decision in some cases. Perhaps in future articles, we can examine the components of performance in greater detail (e.g. frequency, IPC, etc.), but for now, high level guidance seems appropriate – given the level of disclosure from both vendors.