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• #83 Oliverda Topikgazda

  2009-12-08 00:14:16 #83

  Összes hozzászólása itt Válaszok az összes hozzászólására itt Válaszok erre a hozzászólásra

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  Oliverda

  Topikgazda

  JF:

  "There have been some questions about the Bulldozer architecture so this should help clear up any confusion.

  First, Bulldozer is based on a modular architecture where two integer cores are teamed up with an extra-large FPU to create what we call a Bulldozer module. Bulldozer modules are the basis of all of the designs that will be coming from this architecture, and it’s modular nature not only allows us to build processors with different sized core counts but also provides flexibility for future designs that could allow other modular components like GPUs to be added into the designs. The Bulldozer module is a concept and part of an architectural design, it is not something that the user will come in contact with. For instance, when an Interlagos system boots up, the hardware will see 16 integer cores, not 8 modules. When the OS loads, it will see 16 integer cores, not 8 modules, and the applications will see 16 cores as well. Because of this extremely consistent manner by which the whole system sees the integer core (and not modules), it is only natural that Interlagos will be marketed as a 16-core processor. It would actually be more confusing to call it an 8-core processor, because there is no point where a customer would see 8-cores.

  Secondly, there was a question about the amount of die space that is consumed by having 2 integer cores in a module versus just one. Bulldozer was designed to be a modular architecture where 2 integer cores are able to share certain resources where it makes sense (in order to reduce power consumption) yet still retain discrete components in order to ensure great performance and no bottlenecks. It was never designed as a single integer core in each module, so dissecting the module components becomes a bit more tricky. Some have compared this to SMT and made statements that SMT customers could see a modest increase in performance for only a fraction of die space. We believe that our Bulldozer architecture will provide far greater performance gains than SMT with up to 80% greater expected throughput when running 2 threads simultaneously compared to a single thread running on a single integer core. Our engineers estimate that the amount of discrete circuitry that is added to each Bulldozer module in order to allow for a second integer thread to run is ~12% at the core level, but because the integer cores are only a portion of the overall die space , the addition of the second integer core in each module only adds ~5% of circuitry to the total die. We believe this is an excellent balance of greater performance with a very small silicon cost.

  Finally, there are those that have suggested that the two integer cores in the Bulldozer module could potentially be merged together into a single core. This is not true. Perhaps they are confusing the functionality of the FPU, which is flexible enough to be split between the two cores in the module, giving each a 128-bit FMAC simultaneously, OR can be combined into a 256-bit FMAC for one integer core to use exclusively if the second integer core does not need any FPU commands in that cycle.

  We hope this clarifies the questions that seem to be most prevalent."

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