Approximate computing: Difference between revisions

Revision as of 17:06, 21 May 2021

Revision as of 17:07, 21 May 2021

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; Approximate circuits

: Approximate arithmetic circuits:<ref>Jiang et al., "[http://www.ece.ualberta.ca/~jhan8/publications/survey.pdf Approximate Arithmetic Circuits: A Survey, Characterization, and Recent Applications]", the Proceedings of the IEEE, Vol. 108, No. 12, pp. 2108 - 2135, 2020.</ref> [[Adder (electronics)|adders]],<ref>J. Echavarria, et al. "FAU: Fast and Error-Optimized Approximate Adder Units on LUT-Based FPGAs", FPT, 2016.</ref><ref>J. Miao, et al. "[https://repositories.lib.utexas.edu/bitstream/handle/2152/19706/miao_thesis_201291.pdf?sequence=1 Modeling and synthesis of quality-energy optimal approximate adders]", ICCAD, 2012</ref> [[Binary multiplier|multipliers]]<ref>{{Cite book|last=Rehman|first=Semeen|last2=El-Harouni|first2=Walaa|last3=Shafique|first3=Muhammad|last4=Kumar|first4=Akash|last5=Henkel|first5=Jörg|date=2016-11-07|title=Architectural-space exploration of approximate multipliers|publisher=ACM|pages=80|doi=10.1145/2966986.2967005|isbn=9781450344661}}</ref> and other [[logical circuit]]s can reduce hardware overhead.<ref>S. Venkataramani, et al. "[http://algos.inesc-id.pt/projectos/approx/FCT/Ref-15.pdf SALSA: systematic logic synthesis of approximate circuits]", DAC, 2012.</ref><ref>J. Miao, et al. "[http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.453.7870&rep=rep1&type=pdf Approximate logic synthesis under general error magnitude and frequency constraints]", ICCAD, 2013</ref><ref>R. Hegde et al. "[http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.33.8929&rep=rep1&type=pdf Energy-efficient signal processing via algorithmic noise-tolerance]", ISLPED, 1999.</ref> For example, an approximate multi-bit adder can ignore the [[carry chain]] and thus, allow all its sub-adders to perform addition operation in parallel. An important property for well-designed approximate arithmetic circuits is that their error should be unbiased with ideally zero mean, and as a result positive and negative errors will tend to cancel each other rather than accumulate with a bias in the calculations.<ref>S. Hashemi, et al. "[https://ieeexplore.ieee.org/document/7372600 DRUM: A Dynamic Range Unbiased Multiplier for approximate applications]", ICCAD, 2015.</ref>

; Approximate storage

: Instead of [[Computer data storage|storing data]] values exactly, they can be stored approximately, e.g., by [[Data truncation|truncating]] the lower-bits in [[floating point]] data. Another method is accept less reliable memory. For this, in [[DRAM]]<ref>{{Cite journal|last=Raha|first=A.|last2=Sutar|first2=S.|last3=Jayakumar|first3=H.|last4=Raghunathan|first4=V.|date=July 2017|title=Quality Configurable Approximate DRAM|journal=IEEE Transactions on Computers|volume=66|issue=7|pages=1172–1187|doi=10.1109/TC.2016.2640296|issn=0018-9340|doi-access=free}}</ref> and [[eDRAM]], [[refresh rate]] can be lowered or controlled.<ref>{{Cite journal|last=Kim|first=Yongjune|last2=Choi|first2=Won Ho|last3=Guyot|first3=Cyril|last4=Cassuto|first4=Yuval|date=December 2019|title=On the Optimal Refresh Power Allocation for Energy-Efficient Memories|url=https://ieeexplore.ieee.org/document/9013465/|journal=2019 IEEE Global Communications Conference (GLOBECOM)|___location=Waikoloa, HI, USA|publisher=IEEE|pages=1–6|doi=10.1109/GLOBECOM38437.2019.9013465|isbn=978-1-7281-0962-6|arxiv=1907.01112}}</ref> In [[Static random-access memory|SRAM]], supply voltage can be lowered<ref>{{Cite journal|last=Frustaci|first=Fabio|last2=Blaauw|first2=David|last3=Sylvester|first3=Dennis|last4=Alioto|first4=Massimo|date=June 2016|title=Approximate SRAMs With Dynamic Energy-Quality Management|url=https://ieeexplore.ieee.org/document/7372479/|journal=IEEE Transactions on Very Large Scale Integration (VLSI) Systems|volume=24|issue=6|pages=2128–2141|doi=10.1109/TVLSI.2015.2503733|issn=1063-8210}}</ref> or controlled.<ref>{{Cite journal|last=Kim|first=Yongjune|last2=Kang|first2=Mingu|last3=Varshney|first3=Lav R.|last4=Shanbhag|first4=Naresh R.|date=2018|title=Generalized Water-filling for Source-aware Energy-efficient SRAMs|url=https://ieeexplore.ieee.org/document/8368137/|journal=IEEE Transactions on Communications|pages=1–1|doi=10.1109/TCOMM.2018.2841406|issn=0090-6778|arxiv=1710.07153}}</ref> Approximate storage can be applied to reduce [[Magnetoresistive random-access memory|MRAM]]'s high write energy consumption.<ref>{{Cite journal|last=Kim|first=Yongjune|last2=Jeon|first2=Yoocharn|last3=Guyot|first3=Cyril|last4=Cassuto|first4=Yuval|date=June 2020|title=Optimizing the Write Fidelity of MRAMs|url=https://ieeexplore.ieee.org/document/9173990/|journal=2020 IEEE International Symposium on Information Theory (ISIT)|___location=Los Angeles, CA, USA|publisher=IEEE|pages=792–797|doi=10.1109/ISIT44484.2020.9173990|isbn=978-1-7281-6432-8|arxiv=2001.03803}}</ref> In general, any [[error detection and correction]] mechanisms should be disabled.