Multi-core processor: Difference between revisions

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[[File:Athlon64x2-6400plus.jpg|thumb|An AMD [[Athlon 64 X2|Athlon X2 6400+]] dual-core processor]]

A '''multi-core processor''' is a [[microprocessor]] on a single [[integrated circuit]] with two or more separate [[Central processing unit|processing units]], called cores (for example, ''dual-core'' or ''quad-core''), each of which reads and executes [[Instruction set|program instructions]].<ref>{{cite web|url= http://searchdatacenter.techtarget.com/sDefinition/0,,sid80_gci1015740,00.html|publisher= TechTarget|title= Definition: multi-core processor|last= Rouse|first= Margaret|date= March 27, 2007|access-date= March 6, 2013|url-status= dead|archive-url= https://web.archive.org/web/20100805052158/http://searchdatacenter.techtarget.com/sDefinition/0,,sid80_gci1015740,00.html|archive-date= August 5, 2010}}</ref> The instructions are ordinary [[Instruction set|CPU instructions]] (such as add, move data, and branch) but the single processor can run instructions on separate cores at the same time, increasing overall speed for programs that support [[Multithreading (computer architecture)|multithreading]] or other [[parallel computing]] techniques.<ref>{{cite web|url=http://www.csa.com/discoveryguides/multicore/review.pdf|title=Multicore Processors – A Necessity|last=Schauer|first=Bryan|archive-url=https://web.archive.org/web/20111125035151/http://www.csa.com/discoveryguides/multicore/review.pdf|archive-date=2011-11-25|url-status=dead}}</ref> Manufacturers typically integrate the cores onto a single integrated circuit [[Die (integrated circuit)|die]] (known as a chip multiprocessor or CMP) or onto multiple dies in a single [[Chip carrier|chip package]]. The microprocessors currently used in almost all personal computers are multi-core.

A multi-core processor implements [[multiprocessing]] in a single physical package. Designers may couple cores in a multi-core device tightly or loosely. For example, cores may or may not share [[CPU cache|caches]], and they may implement [[message passing]] or [[shared memory|shared-memory]] inter-core communication methods. Common [[network topology|network topologies]] used to interconnect cores include [[bus network|bus]], [[ring network|ring]], two-dimensional [[mesh networking|mesh]], and [[crossbar switch|crossbar]]. Homogeneous multi-core systems include only identical cores; [[heterogeneous computing|heterogeneous]] multi-core systems have cores that are not identical (e.g. [[ARM big.LITTLE|big.LITTLE]] have heterogeneous cores that share the same [[Instruction set architecture|instruction set]], while [[AMD Accelerated Processing Unit]]s have cores that do not share the same instruction set). Just as with single-processor systems, cores in multi-core systems may implement architectures such as [[Very long instruction word|VLIW]], [[Superscalar processor|superscalar]], [[Vector processor|vector]], or [[Multithreading (computer architecture)|multithreading]].