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作者Bulldozer 20 Questions Part2
“How much extra performance will we see when running two-threaded applications on one Bulldozer Module compared to two cores in different modules?” – Simon
Without getting too specific around actual scaling across cores on the processor, let me share with you what was in the Hot Chips presentation. Compared to CMP (chip multiprocessing – which is, in simplistic terms building a multicore chip with each core having its own dedicated resources) two integer cores in a Bulldozer module would deliver roughly 80% of the throughput. But, because they have shared resources, they deliver that throughput at low power and low cost. Using CMP has some drawbacks, including more heat and more die space. The heat can limit performance in addition to consuming more power. Ask yourself, would you rather have a 4-cylinder engine that delivered 300HP or a 6-cylinder engine that delivered 360HP and consumed less gas? The cylinder to horsepower ratio for 4-cylinder is obviously higher (75HP/cylinder vs. the V6’s 60HP/cylinder), meaning that each cylinder can give you more performance. However, looking at the overall enginge, you are getting less total output; and you are getting that lower output at a higher cost (higher gas consumption).
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