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NoC design and optimization for Multi-core media processors

NoC design and optimization for Multi-core media processors

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CHAPTER 2. RELATED WORK 19router elements (crossbars, FIFOs <strong>and</strong> arbiters) by calculating switching capacitances ofindividual circuit elements. Orion contains a library of architectural level parameterizedpower models.The more recent Orion 2.0 presented in [76] is an enhanced <strong>NoC</strong> power <strong>and</strong> areasimulator offering improved accuracy compared to the original Orion framework. Some oftheadditionsintoOrion2.0includeflip-flop<strong>and</strong>clockdynamic<strong>and</strong>leakagepowermodels,link power models, leveraging models developed in [74]. Virtual Channel (VC) allocatormicroarchitectureusesaVCallocationmodel, basedonthemicroarchitecture<strong>and</strong>pipelineproposed in [77]. Application-specific technology-level fine tuning of parameters usingdifferent V th <strong>and</strong> transistor widths are used to increase accuracy of power estimation.Work in [72] explores use of heterogeneous interconnects optimized <strong>for</strong> delay, b<strong>and</strong>widthorpowerbyvarying<strong>design</strong>parameterssuchasabuffersizes,wirewidth<strong>and</strong>numberof repeaters on the interconnects. The work presented in the paper uses Energy-Delay 2as the <strong>optimization</strong> parameter. An evaluation of different configurations of heterogeneousinterconnects is made. The evaluation shows that an optimal configuration (<strong>for</strong> delay,b<strong>and</strong>width, power or power <strong>and</strong> b<strong>and</strong>width) of wires can reduce the total processor ED 2value by up to 11% compared to a <strong>NoC</strong> with homogeneous interconnect in a typicalprocessor.Courtay et. al[73] have developed a high-level delay <strong>and</strong> power estimation tool <strong>for</strong>link exploration that offers similar statistics as Intacte does. The tool allows changingarchitectural level parameters such as different signal coding techniques to analyze theeffects on wire delay/power.Work in [74] proposes delay <strong>and</strong> power models <strong>for</strong> buffered interconnects. The modelscan be constructed from sources such as Liberty[78], LEF/ITF[79], ITRS[80], <strong>and</strong>PTM[81]. The buffered delay models take into account effects of input <strong>and</strong> output slewsof circuit elements in calculating intrinsic delays. The power models include leakage <strong>and</strong>dynamic power dissipation of gates. The area models include technology dependent coefficientsthat can be estimated by linear regression techniques per technology node toestimate repeater areas.

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