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Noise-Direct: A Technique for Power Supply Noise Aware Floorplanning Using Microarchitecture Profiling
Yokohama January 23-January 26
DOI Bookmark: http://doi.ieeecomputersociety.org/10.1109/ASPDAC.2007.3580852007 Asia and South Pacific Design Au ...
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F. Mohamood, Sch. of Electr.&Comput. Eng., Georgia Inst. of Technol., Atlanta, GA
This paper proposes noise-direct, a design methodology for power integrity aware floorplanning, using microarchitectural feedback to guide module placement. Stringent power constraints have led microprocessor designers to incorporate aggressive power saving techniques such as clock-gating, that place a significant burden on the power delivery network. While the application of extensive clock-gating can effectively reduce power consumption, unfortunately, it can also induce large inductive noise (di/dt), resulting in signal integrity and reliability issues. To combat these problems, processors are usually designed for the worst-case current consumption scenario using adequate supply voltage and decoupling capacitances. To tackle high-frequency inductive noise and potential IR drops, we propose a novel design methodology that integrates microarchitectural profiling feedback into the floorplanning process. We present two microarchitectural metrics to quantify the noise susceptibility of a module:self weighting and correlation weighting. By using these metrics in a force-directed floorplanning algorithm to assign power pin affinity to modules, we can quickly converge to a design for average-case current consumption. By designing for the average-case and employing dynamic di/dt control for the worst-case, we can ensure that a chip is noise-tolerant without exceeding decap budget constraints. Our observations showed that certain functional modules in a processor exhibit consistent and highly correlated switching activity, that can be used to guide module placement distance from power pins. The experimental results demonstrate that the force-directed floorplanning technique can effectively suppress supply noise experienced by modules, reduce the total number of supply-noise margin violations, and achieve a floor-plan with considerably lower IR drop, as compared to a wire-length driven floorplan.
Index Terms:
wire-length driven floorplan, noise-direct, power supply noise aware floorplanning, microarchitecture profiling, power constraints, microprocessor designers, aggressive power saving techniques, clock-gating, power delivery network, power consumption reduction, inductive noise, decoupling capacitances, self weighting, correlation weighting, force-directed floorplanning algorithm, power pin affinity, current consumption, di/dt control, supply-noise margin violations
Citation:
F. Mohamood, M.B. Healy, null Sung Kyu Lim, H.-H.S. Lee, "Noise-Direct: A Technique for Power Supply Noise Aware Floorplanning Using Microarchitecture Profiling," asp-dac, pp.786-791, 2007 Asia and South Pacific Design Automation Conference, 2007
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