imprecise computing yavuz yetim. overview motivation background definition and causes of imprecision...
Post on 19-Dec-2015
212 views
TRANSCRIPT
![Page 1: Imprecise Computing Yavuz Yetim. Overview Motivation Background Definition and Causes of Imprecision Solution Approaches Discussion of Two Methods Future](https://reader030.vdocuments.us/reader030/viewer/2022032800/56649d2c5503460f94a02db8/html5/thumbnails/1.jpg)
Imprecise Computing
Yavuz Yetim
![Page 2: Imprecise Computing Yavuz Yetim. Overview Motivation Background Definition and Causes of Imprecision Solution Approaches Discussion of Two Methods Future](https://reader030.vdocuments.us/reader030/viewer/2022032800/56649d2c5503460f94a02db8/html5/thumbnails/2.jpg)
Overview
• Motivation• Background• Definition and Causes of Imprecision• Solution Approaches• Discussion of Two Methods• Future Work
![Page 3: Imprecise Computing Yavuz Yetim. Overview Motivation Background Definition and Causes of Imprecision Solution Approaches Discussion of Two Methods Future](https://reader030.vdocuments.us/reader030/viewer/2022032800/56649d2c5503460f94a02db8/html5/thumbnails/3.jpg)
Motivation
• Precision = Overkill
• Applications inherently imprecision tolerant
• Cosmic Rays
Perfect timing, High Vdd, ECC, CRC, checker circuits
PowerPerformance
![Page 4: Imprecise Computing Yavuz Yetim. Overview Motivation Background Definition and Causes of Imprecision Solution Approaches Discussion of Two Methods Future](https://reader030.vdocuments.us/reader030/viewer/2022032800/56649d2c5503460f94a02db8/html5/thumbnails/4.jpg)
Background
• Vulnerability Factor [Mukherjee, Weaver, Emer, Reinhardt, Austin, 2003]– Not all bits are important (Architectural)– The important bits are not always important (Timing)
Evaluation Method
![Page 5: Imprecise Computing Yavuz Yetim. Overview Motivation Background Definition and Causes of Imprecision Solution Approaches Discussion of Two Methods Future](https://reader030.vdocuments.us/reader030/viewer/2022032800/56649d2c5503460f94a02db8/html5/thumbnails/5.jpg)
Background
• Algorithmic Noise Tolerance [Hegde, Shanbhag, 1999]– Reduce noise in predictable signals
DSP Applications
![Page 6: Imprecise Computing Yavuz Yetim. Overview Motivation Background Definition and Causes of Imprecision Solution Approaches Discussion of Two Methods Future](https://reader030.vdocuments.us/reader030/viewer/2022032800/56649d2c5503460f94a02db8/html5/thumbnails/6.jpg)
Background
• Error Resilient System Architecture
Inflexible, Suboptimal
![Page 7: Imprecise Computing Yavuz Yetim. Overview Motivation Background Definition and Causes of Imprecision Solution Approaches Discussion of Two Methods Future](https://reader030.vdocuments.us/reader030/viewer/2022032800/56649d2c5503460f94a02db8/html5/thumbnails/7.jpg)
Definition of Imprecise Data
• Stochastic Process– Probabilistic Issues– Time Issues
Imprecision
Time
PDFGoogle Page RankOr MIS
Memory bit: Reverse time
![Page 8: Imprecise Computing Yavuz Yetim. Overview Motivation Background Definition and Causes of Imprecision Solution Approaches Discussion of Two Methods Future](https://reader030.vdocuments.us/reader030/viewer/2022032800/56649d2c5503460f94a02db8/html5/thumbnails/8.jpg)
Causes of Imprecision
• Unit: Hardware Faults• Input: Data From Noisy Channel• Operation: Software Bugs
UnitInput Output
Operation
![Page 9: Imprecise Computing Yavuz Yetim. Overview Motivation Background Definition and Causes of Imprecision Solution Approaches Discussion of Two Methods Future](https://reader030.vdocuments.us/reader030/viewer/2022032800/56649d2c5503460f94a02db8/html5/thumbnails/9.jpg)
Solution Approaches
• Decrease imprecision by estimation– ANT approach in software
• Tolerate imprecision by controlling it– ERSA only handles exceptions– Numerical control
• Input: 10-3, Output: 10-2
![Page 10: Imprecise Computing Yavuz Yetim. Overview Motivation Background Definition and Causes of Imprecision Solution Approaches Discussion of Two Methods Future](https://reader030.vdocuments.us/reader030/viewer/2022032800/56649d2c5503460f94a02db8/html5/thumbnails/10.jpg)
Software Support
• Information flow– Hardware-Software– Data-Data
• Ease of use• Efficiency• Resource Management
![Page 11: Imprecise Computing Yavuz Yetim. Overview Motivation Background Definition and Causes of Imprecision Solution Approaches Discussion of Two Methods Future](https://reader030.vdocuments.us/reader030/viewer/2022032800/56649d2c5503460f94a02db8/html5/thumbnails/11.jpg)
Two Analysis Methods
• Probabilistic Method
• Heuristic Method
![Page 12: Imprecise Computing Yavuz Yetim. Overview Motivation Background Definition and Causes of Imprecision Solution Approaches Discussion of Two Methods Future](https://reader030.vdocuments.us/reader030/viewer/2022032800/56649d2c5503460f94a02db8/html5/thumbnails/12.jpg)
Probabilistic Method
int <0.9> b, c;imp int <0.8> a, <0.9, 0.6> d, <0.7> e;.// some code modifying b, ca = b + c;.// some code modifying e.d = a + e; #<0.85a+0.15e, a_def=0, e_def=0>
b c
a e
d
![Page 13: Imprecise Computing Yavuz Yetim. Overview Motivation Background Definition and Causes of Imprecision Solution Approaches Discussion of Two Methods Future](https://reader030.vdocuments.us/reader030/viewer/2022032800/56649d2c5503460f94a02db8/html5/thumbnails/13.jpg)
Heuristic Method
• Keep performance metric for variables• Update all with info from hardware• Feedback for adjusting imprecision
![Page 14: Imprecise Computing Yavuz Yetim. Overview Motivation Background Definition and Causes of Imprecision Solution Approaches Discussion of Two Methods Future](https://reader030.vdocuments.us/reader030/viewer/2022032800/56649d2c5503460f94a02db8/html5/thumbnails/14.jpg)
Comparison
• Probabilistic
– Probabilistic– Operational Overhead– Both online and offline
optimization
• Heuristic
– Definite– Hardware Overhead– Only online optimization
![Page 15: Imprecise Computing Yavuz Yetim. Overview Motivation Background Definition and Causes of Imprecision Solution Approaches Discussion of Two Methods Future](https://reader030.vdocuments.us/reader030/viewer/2022032800/56649d2c5503460f94a02db8/html5/thumbnails/15.jpg)
Future Work
• Combine two methods• Better evaluation for different methods• Compiler, architecture and hardware support• Power and Performance evaluations
![Page 16: Imprecise Computing Yavuz Yetim. Overview Motivation Background Definition and Causes of Imprecision Solution Approaches Discussion of Two Methods Future](https://reader030.vdocuments.us/reader030/viewer/2022032800/56649d2c5503460f94a02db8/html5/thumbnails/16.jpg)
Thank you…