lect02-power-variability

lect02-power-variability - TechnologyChallenges:...

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Technology Challenges: Power and Variability Prof. Mikko H. Lipasti University of Wisconsin Madison Thanks to Jungseob Lee and Nam Sung Kim for contributing slides to this lecture Readings Read on your own: J. Lee and N. Kim, "Optimizing Total Power of Many Core Processor Considering Supply Voltage Scaling Limit and Process Variations," IEEE/ACM Int. Symp. on Low Power Electronic Design (ISLPED), Aug 2009. Jacobson, H, et al., “Stretching the limits of clock gating efficiency in server class processors,” in Proceedings of HPCA 11, 2005. Shekhar Borkar, Designing Reliable Systems from Unreliable Components: The Challenges of Transistor Variability and Degradation, IEEE Micro 2005, November/December 2005 (Vol. 25, No. 6) pp. 10 16. 2011 ITRS Roadmap ‐‐ Executive Summary. Read the introduction and flip through Grand Challenges. CMOS Scaling Historic CMOS scaling Doubling every two years (Moore’s law) Feature size Device density Device switching speed improves 30 40%/generation dd, V th ) Projected CMOS scaling Feature size, device density scaling continues ~10 year roadmap out to sub 10nm generation Switching speed improves ~20%/generation or less Voltage scaling has tapered off SRAM cell stability becomes an issue at ~0.7V V dd Power Density [Hu et al, MICRO ’03 tutorial] Power density increasing exponentially Power delivery, packaging, thermal implications Thermal effects on leakage, delay, reliability, etc. Dynamic Power Aka AC power, switching power Static CMOS: current flows when transistors turn on/off Combinational logic evaluates Sequential logic (flip flop, latch) captures new value (clock edge) Terms V: supply voltage A: activity factor f: frequency Moore’s Law: which terms increase, which decrease? Voltage scaling has been saving our bacon! Af kCV P dyn 2 Reducing Dynamic Power Reduce capacitance Simpler, smaller design (yeah right) Reduced IPC Reduce activity Smarter design Reduced IPC Reduce frequency Often in conjunction with reduced voltage Reduce voltage Biggest hammer due to quadratic effect, widely employed Can be static (binning/sorting of parts), and/or
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lect02-power-variability - TechnologyChallenges:...

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