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Tuesday, January 6, 2009

Multi-core

A multi-core processor (or chip-level multiprocessor, CMP) combines two or more independent cores into a single package composed of a single (IC), or more dies packaged together. A dual-core processor contains two cores, and a quad-core processor contains four cores. A multi-core microprocessor implements in a single physical package. A processor with all cores on a single die is called a monolithic processor. Cores in a multicore device may share a single coherent at the highest on-device cache level ( or may have separate caches (e.g. current dual-core processors). The processors also share the same interconnect to the rest of the system. Each "core" independently implements optimizations such as execution, and . A system with n cores is effective when it is presented with n or more . The most commercially significant (or at least the most 'obvious') multi-core processors are those used in (primarily from Intel and AMD) and game consoles (e.g., the eight-core processor in the and the three-core in the ). In this context, "multi" typically means a relatively small number of cores. However, the technology is widely used in other technology areas, especially those of as and in GUI

The amount of performance gained by the use of a multicore processor depends on the problem being solved and the algorithms used, as well as their implementation in software . For so-called problems, a dual-core processor with two cores at 2GHz may perform very nearly as quickly as a single core of 4GHz. Other problems, though, may not yield so much speedup. This all assumes, however, that the software has been designed to take advantage of available parallelism. If it hasn't, there will not be any speedup at all. However, the processor will better since it can run two programs at once, one on each core.

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