25 research outputs found
Privacy Leakages in Approximate Adders
Approximate computing has recently emerged as a promising method to meet the
low power requirements of digital designs. The erroneous outputs produced in
approximate computing can be partially a function of each chip's process
variation. We show that, in such schemes, the erroneous outputs produced on
each chip instance can reveal the identity of the chip that performed the
computation, possibly jeopardizing user privacy. In this work, we perform
simulation experiments on 32-bit Ripple Carry Adders, Carry Lookahead Adders,
and Han-Carlson Adders running at over-scaled operating points. Our results
show that identification is possible, we contrast the identifiability of each
type of adder, and we quantify how success of identification varies with the
extent of over-scaling and noise. Our results are the first to show that
approximate digital computations may compromise privacy. Designers of future
approximate computing systems should be aware of the possible privacy leakages
and decide whether mitigation is warranted in their application.Comment: 2017 IEEE International Symposium on Circuits and Systems (ISCAS
Ultra-Fast, High-Performance 8x8 Approximate Multipliers by a New Multicolumn 3,3:2 Inexact Compressor and its Derivatives
Multiplier, as a key role in many different applications, is a
time-consuming, energy-intensive computation block. Approximate computing is a
practical design paradigm that attempts to improve hardware efficacy while
keeping computation quality satisfactory. A novel multicolumn 3,3:2 inexact
compressor is presented in this paper. It takes three partial products from two
adjacent columns each for rapid partial product reduction. The proposed inexact
compressor and its derivates enable us to design a high-speed approximate
multiplier. Then, another ultra-fast, high-efficient approximate multiplier is
achieved utilizing a systematic truncation strategy. The proposed multipliers
accumulate partial products in only two stages, one fewer stage than other
approximate multipliers in the literature. Implementation results by Synopsys
Design Compiler and 45 nm technology node demonstrates nearly 11.11% higher
speed for the second proposed design over the fastest existing approximate
multiplier. Furthermore, the new approximate multipliers are applied to the
image processing application of image sharpening, and their performance in this
application is highly satisfactory. It is shown in this paper that the error
pattern of an approximate multiplier, in addition to the mean error distance
and error rate, has a direct effect on the outcomes of the image processing
application.Comment: 21 Pages, 18 Figures, 6 Table
Bit Based Approximation for Approx-NoC: A Data Approximation Framework for Network-On-Chip Architectures
The dawn of the big data era has led to the inception of new and creative compute paradigms that utilize heterogeneity, specialization, processor-in-memory and approximation due to the high demand for memory bandwidth and power. Relaxing the constraints of applications has led to approximate computing being put forth as a feasible solution for high performance computation. The latest fad such as machine learning, video/image processing, data analytics, neural networks and other data intensive applications have heightened the possibility of using approximate computing as a feasible solution as these applications allow imprecise output within a specific error range.
This work presents Bit Based Approx-NoC, a hardware data approximation framework with a lightweight bit-based approximation technique for high performance NoCs. Bit-Based Approx-NoC facilitates approximate matching of data patterns, within a controllable error range, to compress them thereby reducing the data movement across the chip. The proposed work exploits the entropy between data words in order to increase their inherent compressibility. Evaluations in this work show on average 5% latency reduction and 14% throughput improvement compared to the state of the art NoC compression mechanisms
Chisel: Reliability- and Accuracy-Aware Optimization of Approximate Computational Kernels
The accuracy of an approximate computation is the distance between the result that the computation produces and the corresponding fully accurate result. The reliability of the computation is the probability that it will produce an acceptably accurate result. Emerging approximate hardware platforms provide approximate operations that, in return for reduced energy consumption and/or increased performance, exhibit reduced reliability and/or accuracy.
We present Chisel, a system for reliability- and accuracy-aware optimization of approximate computational kernels that run on approximate hardware platforms. Given a combined reliability and/or accuracy specification, Chisel automatically selects approximate kernel operations to synthesize an approximate computation that minimizes energy consumption while satisfying its reliability and accuracy specification.
We evaluate Chisel on five applications from the image processing, scientific computing, and financial analysis domains. The experimental results show that our implemented optimization algorithm enables Chisel to optimize our set of benchmark kernels to obtain energy savings from 8.7% to 19.8% compared to the fully reliable kernel implementations while preserving important reliability guarantees.National Science Foundation (U.S.) (Grant CCF-1036241)National Science Foundation (U.S.) (Grant CCF-1138967)National Science Foundation (U.S.) (Grant IIS-0835652)United States. Dept. of Energy (Grant DE-SC0008923)United States. Defense Advanced Research Projects Agency (Grant FA8650-11-C-7192)United States. Defense Advanced Research Projects Agency (Grant FA8750-12-2-0110)United States. Defense Advanced Research Projects Agency (Grant FA-8750-14-2-0004