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Using Mobile Sinks in WSN: Computational Complexity and a Theoretical Bound

电子学报(英文版) 2011年第1期20卷 147-150页

作者： GU Yu JI Yusheng CHEN Hongyang ZHAO Baohua Department of Computer Science University of Science and Technology of China Hefei China State Key Laboratory of Networking and Switching Technology Beijing China Information Systems Architecture Science Research Division NII Tokyo Japan Institute of Industrial Science University of Tokyo Tokyo Japan

In this paper, we study the lifetime op- timization problem in wireless sensor networks using mo- bile sink nodes. This problem is inherently difficult since we need to consider both sink scheduling and data rout- ing. Through a simple case study we develop a novel no- tation named the Placement pattern (PP) to bound traffic patterns with candidate locations. This significantly de- creases the number of elements needed to be scheduled. Based on the PP, we mathematically formulate this opti- mization problem as a Mixed-integer non-linear program- ming (MINLP), which is very tough and time consuming to solve. By proving that the problem is NP-complete, we point out that instead of seeking an optimal algorithm, heuristic algorithms, especially those with performance guarantee, would be much more desirable to develop. Fur- thermore, in order to help identify performance gains of heuristic algorithms proposed in the future, we develop a Linear programming (LP) formulation which serves as an upper bound by adopting a reformulation and relaxation technique.

关键词：无线传感器网络移动接收计算复杂性混合整数非线性规划启发式算法 NP完全问题优化问题 MINLP

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Persistent B+-Trees in non-volatile main memory 41st

Persistent B+-Trees in non-volatile main memory

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41st International Conference on Very Large Data Bases, VLDB 2015

作者： Chen, Shimin Jin, Qin State Key Laboratory of Computer Architecture Institute of Computing Technology Chinese Academy of Sciences China Computer Science Department School of Information Renmin University of China China

computer systems in the near future are expected to have Non- Volatile Main Memory (NVMM), enabled by a new generation of Non-Volatile Memory (NVM) technologies, such as Phase Change Memory (PCM), STT-MRAM, and Memristor. The non-volatility property has the promise to persist in-memory data structures for instantaneous failure recovery. However, realizing such promise requires a careful design to ensure that in-memory data structures are in known consistent states after failures. This paper studies persistent in-memory B+-Trees as B+-Trees are widely used in database and data-intensive systems. While traditional techniques, such as undo-redo logging and shadowing, support persistent B+-Trees, we find that they incur drastic performance overhead because of extensive NVM writes and CPU cache flush operations. PCM-friendly B+-Trees with unsorted leaf nodes help mediate this issue, but the remaining overhead is still large. In this paper, we propose write atomic B+-Trees (wB+-Trees), a new type of main-memory B+-Trees, that aim to reduce such overhead as much as possible. wB+-Tree nodes employ a small indirect slot array and/or a bitmap so that most insertions and deletions do not require the movement of index entries. In this way, wB+- Trees can achieve node consistency either through atomic writes in the nodes or by redo-only logging. We model fast NVM using DRAM on a real machine and model PCM using a cycle-accurate simulator. Experimental results show that compared with previous persistent B+-Tree solutions, wB+-Trees achieve up to 8.8x speedups on DRAM-like fast NVM and up to 27.1x speedups on PCM for insertions and deletions while maintaining good search performance. Moreover, we replaced Memcached's internal hash index with tree indices. Our real machine Memcached experiments show that wB+-Trees achieve up to 3.8X improvements over previous persistent tree structures with undo-redo logging or shadowing. © 2015 VLDB Endowment 21508097/15/03.

关键词： Dynamic random access storage

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An energy-aware file relocation strategy based on file-access frequency and correlations 15th

An energy-aware file relocation strategy based on file-acces...

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15th International Conference on Algorithms and architectures for Parallel Processing, ICA3PP 2015

作者： Hu, Cheng Deng, Yuhui Department of Computer Science Jinan University Guangzhou510632 China State Key Laboratory of Computer Architecture Institute of Computing Chinese Academy of Sciences Beijing100190 China

ISBN: (纸本)9783319271392

Energy consumption has become a big challenge of the traditional storage systems due to the explosive growth of data. A lot of research efforts have been invested in reducing the energy consumption of those systems. Traditionally, the frequently accessed data are concentrated into a small part of hot storage nodes, and other cold storage nodes are switched to a low-power state, thus saving energy. However, due to the energy penalty and time penalty, it takes extra energy and generates additional delay to switch a cold storage node from a low-power state to an active state. In contrast to the existing work, this paper proposes a Skew File Relocate (SFR) strategy which aggregates the correlated cold files to the same cold storage node in addition to concentrating the frequently accessed files to the hot nodes. Because the correlated files are normally accessed together, SFR can significantly reduce the number of power state transitions and lengthen the idle periods that the cold storage nodes are experienced, thus saving more energy and improving the system response time. Furthermore, other three relocation strategies are designed to explore the performance behavior of SFR. Experimental results demonstrate that SFR can significantly reduce the energy consumption while maintaining the system performance at an acceptable level. © 2015 Springer International Publishing Switzerland.

关键词： Cold storage

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Feedback-controlled security-aware and energy-efficient scheduling for real-time embedded systems

Feedback-controlled security-aware and energy-efficient sche...

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7th International Conference on Embedded and Multimedia Computing, EMC 2012

作者： Ma, Yue Sang, Nan Jiang, Wei Zhang, Lei School of Computer Science and Engineering University of Electronic Science and Technology of China Chengdu China State Key Laboratory of Computer Architecture Institute of Computing Technology Chinese Academy of Sciences Beijing China

ISBN: (纸本)9789400750753

Security has become an important characteristic for many real-time systems. Due to the lack of enough and stable energy supply in battery-powered embedded systems, one of the foremost challenges is the mismatch between energy and performance requirements of security processing. In this paper, we propose a security-aware and energy-efficient scheduling algorithm that aims at reducing energy consumption while ensuring the real-time and security requirements. Based on the feedback control theory, we employ a feedback unit to keep track of the CPU utilization and manage the security level dynamically. Simulation results show the effectiveness and efficiency of the proposed algorithm. © 2012 Springer science+Business Media.

关键词： Feedback control

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I/O lower bounds for auto-tuning of convolutions in CNNs 21

I/O lower bounds for auto-tuning of convolutions in CNNs

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26th ACM SIGPLAN Symposium on Principles and Practice of Parallel Programming, PPoPP 2021

作者： Zhang, Xiaoyang Xiao, Junmin Tan, Guangming State Key Laboratory of Computer Architecture Institute of Computing Technology Chinese Academy of Sciences University of Chinese Academy of Science China

ISBN: (纸本)9781450382946

Convolution is the most time-consuming part in the computation of convolutional neural networks (CNNs), which have achieved great successes in numerous practical applications. Due to the complex data dependency and the increase in the amount of model samples, the convolution suffers from high overhead on data movement (i.e., memory access). This work provides comprehensive analysis and methodologies to minimize the communication for the convolution in CNNs. With an in-depth analysis of the recent I/O complexity theory under the red-blue game model, we develop a general I/O lower bound theory for a composite algorithm which consists of several different sub-computations. Based on the proposed theory, we establish the data movement lower bound results for two main convolution algorithms in CNNs, namely the direct convolution and Winograd algorithm, which represents the direct and indirect implementations of a convolution respectively. Next, derived from I/O lower bound results, we design the near I/O-optimal dataflow strategies for the two main convolution algorithms by fully exploiting the data reuse. Furthermore, in order to push the envelope of performance of the near I/O-optimal dataflow strategies further, an aggressive design of auto-tuning based on I/O lower bounds, is proposed to search an optimal parameter configuration for the direct convolution and Winograd algorithm on GPU, such as the number of threads and the size of shared memory used in each thread block. Finally, experiment evaluation results on the direct convolution and Winograd algorithm show that our dataflow strategies with the auto-tuning approach can achieve about 3.32× performance speedup on average over cuDNN. In addition, compared with TVM, which represents the state-of-the-art technique for auto-tuning, not only our auto-tuning method based on I/O lower bounds can find the optimal parameter configuration faster, but also our solution has higher performance than the optimal solution provided

关键词： Convolution

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Pedestrian wind flow prediction using spatial-frequency generative adversarial network

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Building Simulation 2024年第2期17卷 319-334页

作者： Pengyue Wang Maozu Guo Yingeng Cao Shimeng Hao Xiaoping Zhou Lingling Zhao School of Architecture and Urban Planning Beijing University of Civil Engineering and ArchitectureBeijing100044China Beijing Key Laboratory of Intelligent Processing for Building Big Data Beijing100044China School of Electrical and Information Engineering Beijing University of Civil Engineering and ArchitectureBeijing100044China School of Computer Science and Technology Harbin Institute of TechnologyHarbin150001China

Pedestrian wind flow is a critical factor in designing livable residential environments under growing complex urban *** pedestrian wind flow during the early design stages is essential but currently suffers from inefficiencies in numerical *** learning,particularly generative adversarial networks(GAN),has been increasingly adopted as an alternative method to provide efficient prediction of pedestrian wind ***,existing GAN-based wind flow prediction schemes have limitations due to the lack of considering the spatial and frequency characteristics of wind flow *** study proposes a novel approach termed SFGAN,which embeds spatial and frequency characteristics to enhance pedestrian wind flow *** the spatial domain,Gaussian blur is employed to decompose wind flow into components containing wind speed and distinguished flow edges,which are used as the embedded spatial *** information of wind flow is obtained through discrete wavelet transformation and used as the embedded frequency *** spatial and frequency characteristics of wind flow are jointly utilized to enforce consistency between the predicted wind flow and ground truth during the training phase,thereby leading to enhanced *** results demonstrate that SFGAN clearly improves wind flow prediction,reducing Wind_MAE,Wind_RMSE and the Fréchet Inception Distance(FID)score by 5.35%,6.52%and 12.30%,compared to the previous best method,*** also analyze the effectiveness of incorporating the spatial and frequency characteristics of wind flow in predicting pedestrian wind *** reduces errors in predicting wind flow at large error intervals and performs well in wake regions and regions surrounding *** enhanced predictions provide a better understanding of performance variability,bringing insights at the early design stage to improve pedestrian wind *** proposed spatial-frequen

关键词： pedestrian wind flow prediction generative adversarial network Gaussian kernel wavelet transform objective function

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Design automation methodology from RTL to gate-level netlist and schematic for RSFQ logic circuits 20

Design automation methodology from RTL to gate-level netlist...

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30th Great Lakes Symposium on VLSI, GLSVLSI 2020

作者： Fu, Rongliang Zhang, Zhi-Min Tang, Guang-Ming Huang, Junying Ye, Xiao-Chun Fan, Dong-Rui Sun, Ning-Hui State Key Laboratory of Computer Architecture Institute of Computing Technology Chinese Academy of Sciences China School of Computer Science and Technology University of Chinese Academy of Sciences Beijing China

ISBN: (纸本)9781450379441

The superconducting rapid single flux quantum (RSFQ) logic circuit has the characteristics of high speed and low power consumption, making it an attractive candidate for future supercomputers. However, computer-aided design (CAD) tools for CMOS cannot be directly applied to RSFQ logic due to their distinct properties. For instance, the RSFQ logic gate can work properly when all its fan-ins have the same logic level. This paper presents the design flow from RTL to RSFQ logic netlist and schematic. First, we implement logic synthesis for RSFQ logic circuits. It achieves path balancing while minimizing the number of DFFs. In addition, we propose an automatic schematic generator for the RSFQ logic circuits. It converts the synthesized netlist into its equivalent schematic. A layer assignment algorithm is proposed, which makes all gates layered in the order of the clock arrival time. Experimental results with ISCAS85 and EPFL benchmarks along with some Kogge-Stone adders have shown a 29.2% reduction in the number of DFFs over the breadth-first first search;moreover, 59.57% and 5.3% decrease in the number of layers of the schematic and number of edge crossings over the ELK tool. © 2020 Association for Computing Machinery.

关键词： Logic circuits

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Statistical static timing analysis for circuit aging prediction

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The Journal of China Universities of Posts and Telecommunications 2021年第2期28卷 14-23页

作者： Duan Shengyu Zhai Dongyao Lu Yue Shanghai Engineering Research Center of Intelligent Computing System Shanghai UniversityShanghai 200444China State Key Laboratory of Computer Architecture Institute of Computing TechnologyChinese Academy of SciencesBeijing 100190China School of Electronics and Computer Science University of SouthamptonSouthamptonUK

Complementary metal oxide semiconductor(CMOS)aging mechanisms including bias temperature instability(BTI)pose growing concerns about circuit *** results in threshold voltage increases on CMOS transistors,causing delay shifts and timing violations on logic *** amount of degradation is dependent on the circuit workload,which increases the challenge for accurate BTI aging prediction at the design *** this paper,a BTI prediction method for logic circuits based on statistical static timing analysis(SSTA)is proposed,especially considering the correlation between circuit workload and BTI *** consists of a training phase,to discover the relationship between circuit scale and the required workload samples,and a prediction phase,to present the degradations under different workloads in Gaussian probability *** method can predict the distribution of degradations with negligible errors,and identify 50%more BTI-critical paths in an affordable time,compared with conventional methods.

关键词： bias temperature instability(BTI) reliability prediction statistical static timing analysis(SSTA)

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HDCat: Effectively identifying hot data in large-Scale I/O streams with enhanced temporal locality 15th

HDCat: Effectively identifying hot data in large-Scale I/O s...

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15th International Conference on Algorithms and architectures for Parallel Processing, ICA3PP 2015

作者： Chen, Jiahao Deng, Yuhui Huang, Zhan Department of Computer Science Jinan University Guangzhou510632 China State Key Laboratory of Computer Architecture Institute of Computing Technology Chinese Academy of Sciences Beijing100190 China

ISBN: (纸本)9783319271217

Hot data is very important for optimizing modern computer systems. For example, the identified hot data can be employed to extend the lifespan of flash memory. However, it is very challenging to effectively identify hot data with low memory consumption and low runtime overhead. This paper proposes a Hot Data Catcher (HDCat) which can effectively identify hot data in large-scale I/O streams by leveraging enhanced temporal locality. HDCat only maintains a hot data queue and a candidate hot data queue to record the data access pattern by tracking limited data set, thus effectively reducing the memory consumption. Furthermore, HDCat adopts a D-bit counter and a recency-bit to leverage both the frequency and recency contained in the data stream. Additionally, HDCat can significantly reduce the conversion between hot data and cold data. Real traces are used to evaluate the proposed approach. Experimental results demonstrate that HDCat significantly outperforms the state-of-the-art Multi-hash algorithm and the two-level LRU algorithm. © Springer International Publishing Switzerland 2015.

关键词： Hash functions

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Designing a power-aware replication strategy for storage clusters

Designing a power-aware replication strategy for storage clu...

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2013 IEEE International Conference on Green Computing and Communications and IEEE Internet of Things and IEEE Cyber, Physical and Social Computing, GreenCom-iThings-CPSCom 2013

作者： Zhang, Lingwei Deng, Yuhui Department of Computer Science Jinan University Guangzhou 510632 China State Key Laboratory of Computer Architecture Institute of Computing Technology Chinese Academy of Sciences Beijing 100190 China

ISBN: (纸本)9780769550466

The exponential data growth is presenting challenges to traditional storage systems. Component-based cluster storage systems, due to their high scalability, are becoming the architecture of next generation storage systems. Cluster storage systems often use data replication to ensure high availability, fault tolerance, and load balance. However, this kind of data replication not only consumes a large amount of storage resources, but also generates more energy consumption. This paper presents a power-aware data replication strategy by leveraging data access behavior. This strategy uses 80/20 rule (80% of the data accesses often go to 20% of the storage space) to replicate only a small amount of frequently accessed data. Furthermore, the storage nodes are divided into a hot node set and a cold node set. Hot nodes, which store a small amount of hot data copies, are always in an active state to guarantee the QoS of the system. The cold nodes which store a large number of infrequently accessed cold data, are placed in a low power state, thus reducing the energy consumption of the cluster storage system. The experimental results show that the proposed strategy can effectively reduce the resource and energy consumption of the system, while ensuring the system performance. © 2013 IEEE.

关键词： Energy utilization

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