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Optimal Review Strategy for concurrent execution of Design-Construction Tasks in DB Mode

JOURNAL OF CONSTRUCTION ENGINEERING AND MANAGEMENT 2023年第1期149卷

作者： Wang, Ting Feng, Jingchun Hohai Univ Business Sch Nanjing 211100 Jiangsu Peoples R China

In traditional design-bid-build (DBB) mode, due to the sequential execution of design and construction, the review method of construction documentations is a one-time review at the beginning of the construction phase. However, in design-build (DB) mode, to realize the concurrent execution between design and construction tasks, the review method of construction documentations is multiple reviews during the concurrent execution, and the problem of when and how to review under this review method has not been solved yet. Therefore, dynamic and static decision models are creatively constructed to solve when and how to review. Based on the dynamic decision model, the influence of the execution of the review strategy on the preparation duration, review duration, executable tasks and rework duration during construction was discussed. Based on the static decision model, the influence of design accuracy, construction sensitivity, and review efficiency on the review method under different time ratios was discussed. The research achievements provide operational countermeasures for exploring the principles of developing review strategies in the concurrent execution process from the perspective of quantitative analysis, and also provide directional suggestions for the way of applying concurrent engineering in DB mode.

关键词： Design-bid-build (DBB) mode Design-build (DB) mode concurrent execution Review strategy Dynamic decision model Static decision model

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Modeling and optimization of concurrent execution process of coupled design-construction tasks under design-build mode

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concurrent ENGINEERING-RESEARCH AND APPLICATIONS 2022年第4期30卷 353-366页

作者： Wang, Ting Feng, Jingchun Hohai Univ Business Sch Nanjing 211100 Peoples R China

concurrent execution of design and construction tasks is an important way to realize the integration of them in design-build (DB) mode, but it may bring about period risk due to multiple rework and frequent information transfer in local scope. To solve this problem, this study constructs a concurrent execution strategy model from the perspective of quantitative analysis with the decision goal of minimizing the total execution duration. The results show that: first, when the probability of information change between design and construction tasks decreases gradually, the optimal overlap degree increases and the optimal parallelism decreases. Second, learning effect can effectively shorten the minimum duration corresponding to the optimal overlap degree under any degree of parallelism. Thirdly, with the decrease of the probability of information change between design and construction tasks and the strengthening of learning effect, the shortening rate of the actual execution duration corresponding to the optimal parallelism will be gradually greater than the increasing rate of the actual execution duration. The findings of the study provide suggestions for exploring the mechanism of concurrent execution in DB mode, and also provide countermeasures for better realization of integration of design and construction in DB mode.

关键词： design-build (DB) mode concurrent execution design and construction tasks actual execution duration probability of information change

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Schedulability Analysis of Rate-Monotonic Algorithm on concurrent execution of Digraph Real-Time Tasks 11th

Schedulability Analysis of Rate-Monotonic Algorithm on Concu...

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11th International Workshop on Structured Object-Oriented Formal Language (SOFL) / Workshop on Modeling, Simulation and Verification Language (MSVL)

作者： Cui, Jin Lu, Xu Yu, Guangliang Yu, Bin Xian Shiyou Univ Xian 710065 Peoples R China Xidian Univ ICTT Xian 710071 Peoples R China Xidian Univ ISN Lab Xian 710071 Peoples R China Beijing Inst Control Engn Beijing 100190 Peoples R China

ISBN: (纸本)9783031294754;9783031294761

Rate-monotonic algorithm is a classical algorithm for scheduling periodical tasks. Lots of work has been carried out to analyze the schedulability of RMS algorithm. While most of the work focus on the classical Liu and Layland task model. In this paper, we propose an approach to testing the schedulability of RMS algorithm on digraph task models. Our approach has higher efficiency since we just analyze schedulability of subtasks in the scheduling point set of one time interval rather than all possible cases.

关键词： Schedulability analysis Digraph real-time tasks Rate-monotonic algorithm Real-time systems concurrent execution

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Performance and Power Prediction for concurrent execution on GPUs

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ACM TRANSACTIONS ON ARCHITECTURE AND CODE OPTIMIZATION 2022年第3期19卷 35-35页

作者： Moolchandani, Diksha Kumar, Anshul Sarangi, Smruti R. Indian Inst Technol Delhi Delhi India IIT Delhi IITDelhi Sch Informat Technol Sch Informat Technol Delhi India IIT Delhi Dept Comp Sci Delhi India

The unprecedented growth of edge computing and 5G has led to an increased offloading of mobile applications to cloud servers or edge cloudlets.1 The most prominent workloads comprise computer vision applications. Conventional wisdom suggests that computer vision workloads perform significantly well on SIMD/SIMT architectures such as GPUs owing to the dominance of linear algebra kernels in their composition. In this work, we debunk this popular belief by performing a lot of experiments with the concurrent execution of these workloads, which is the most popular pattern in which these workloads are executed on cloud servers. We show that the performance of these applications on GPUs does not scale well with an increase in the number of concurrent applications primarily because of contention at the shared resources and lack of efficient virtualization techniques for GPUs. Hence, there is a need to accurately predict the performance and power of such ensemble workloads on a GPU. Sadly, most of the prior work in the area of performance/power prediction is for only a single application. To the best of our knowledge, we propose the first machine learning-based predictor to predict the performance and power of an ensemble of applications on a GPU. In this article, we show that by using the execution statistics of stand-alone workloads and the fairness of execution when these workloads are executed with three representative microbenchmarks, we can get a reasonably accurate prediction. This is the first such work in the direction of performance and power prediction for concurrent applications that does not rely on the features extracted from concurrent executions or GPU profiling data. Our predictors achieve an accuracy of 91% and 96% in estimating the performance and power of executing two applications concurrently, respectively. We also demonstrate a method to extend our models to four or five concurrently running applications on modern GPUs.

关键词： Power and performance prediction machine learning concurrent execution GPUs

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Multi-objective joint optimization for concurrent execution of design-construction tasks in design-build mode

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AUTOMATION IN CONSTRUCTION 2023年 156卷

作者： Wang, Ting Feng, Jingchun Hohai Univ Business Sch Nanjing 211100 Jiangsu Peoples R China

PERT (Program Evaluation and Review Technique) is suitable for evaluating schedule optimization of DBB (Design-Bid-Build) projects based on serial execution of design and construction. However, it is not suitable for evaluating the multi-objective joint optimization of DB (Design-Build) projects based on concurrent execution of design and construction. Therefore, focusing on the unique construction method and construction objective under DB mode, this study adopts the multi-parameter grey GERT (Graphical Evaluation and Review Technique) based on z-tag to construct a multi-objective joint optimization model of concurrent execution of designconstruction tasks. The research methods adopted are as follows: Firstly, based on the modeling idea of PERT, a multi-parameter grey GERT was constructed, which was composed of sub-GERTs representing the execution flow of design-construction tasks. Second, based on discussing the functional relationship between time, cost and quality in normal execution and rework execution, a method of constructing a moment generating function for concurrent execution time, cost and quality to characterize the uncertainty of input and output parameters is proposed. Thirdly, on the basis of analyzing the solving methods of each parameter of the multi-parameter GERT, the solving methods for starting execution time, information transmission duration, and total execution duration of the critical time nodes are given. Finally, according to the requirements of DB projects, the multi-objective joint optimization models based on progress oriented and quality oriented are constructed respectively, and the gamultiobj algorithm is used to solve the models. The proposed approach provides a scientific quantitative analysis method for evaluating the progress, cost and quality objectives of the concurrent execution of designconstruction tasks, and also lays theoretical guidance for further efficiency popularization of DB mode.

关键词： DB (design-build) mode concurrent execution GERT (graphical evaluation and review Multi-objective joint optimization Gamultiobj algorithm technique)

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Boosting State Machine Replication with concurrent execution 8

Boosting State Machine Replication with Concurrent Execution

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8th Latin-American Symposium on Dependable Computing (LADC)

作者： Alchieri, Eduardo Dotti, Fernando Marandi, Parisa Mendizabal, Odorico Pedone, Fernando Univ Brasilia Dept Ciencia Computacao Brasilia DF Brazil Pontificia Univ Catolica Rio Grande do Sul Escola Politecn Porto Alegre RS Brazil Microsoft Reading Berks England Univ Fed Rio Grande FURG Rio Grande Brazil USI Lugano Switzerland

ISBN: (纸本)9781538684894

State machine replication is a fundamental technique to render services fault tolerant. One of the key assumptions of state machine replication is that replicas must execute operations deterministically. Deterministic execution often translates into sequential execution of requests at replicas. With the increasing demand for dependable services and widespread use of multi-core servers, several proposals for enabling concurrent execution in state machine replication have appeared in the literature. Invariably, these techniques exploit the fact that independent operations, those that do not share any common state or do not update shared state, can execute concurrently. Existing protocols differ in several important ways. In this paper, we survey this field of research and discuss the main aspects of the different protocols. Central aspects include conflict detection, representation and enforcing;tradeoffs involving existing architectures and level of allowed parallelism;workload-driven adaptation schemes;and implications of parallel state machine replication to recovery. Moreover, we discuss ongoing and future work directions for high-throughput state machine replication.

关键词： Replication Scheduling concurrent execution

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Accelerating block lifecycle on blockchain via hardware transactional memory

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JOURNAL OF PARALLEL AND DISTRIBUTED COMPUTING 2024年 184卷

作者： Li, Yue Liu, Han Gao, Jianbo Zhang, Jiashuo Guan, Zhi Chen, Zhong Peking Univ Sch Comp Sci Beijing Peoples R China Tsinghua Univ Beijing Peoples R China Peking Univ Chongqing Res Inst Big Data Chongqing Peoples R China Peking Univ Natl Engn Res Ctr Software Engn Beijing Peoples R China

The processing of block lifecycles is essential to the efficiency of a blockchain, which consists of four steps: creation, execution, consensus, and validation. The permissionless blockchain systems typically had very limited transaction throughput because of the performance bottleneck of consensus protocols. With recent advances in consensus protocols, the execution and validation of transactions have become the new performance bottleneck. We propose a novel framework, called FASTBLOCK, to speed up the execution and validation steps by introducing fine-grained concurrency. Our early design of FASTBLOCK supported three key modules: (1) a symbolic execution -based analyzer that automatically identifies minimal atomic sections in each transaction;(2) a concurrent execution step that executes possibly conflicting transactions in parallel using hardware transactional memory;(3) a concurrent validation step that introduces a happen-before relation to deterministically re-execute *** improved FASTBLOCK presented in this article supports the nonce mechanism to schedule concurrent transactions from the same account. Moreover, we empirically study the impact of concurrency on Ethereum except for performance and shed light on potential optimizations of FASTBLOCK. Finally, we implemented FASTBLOCK and then evaluated the performance of FASTBLOCK. Our result shows that the FASTBLOCK outperforms state-of-art solutions significantly in performance: the execution step and validation step speed up to 3.0x and 2.3x on average over the original serial model, respectively, with eight concurrent threads. In addition, we evaluated the impact of the nonce mechanism, and the result shows that the performance loss caused by this mechanism is acceptable in practice.

关键词： Blockchain Ethereum Smart contract Hardware transaction memory concurrent execution

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On Off-Chaining Smart Contract Runtime Protection: A Queuing Model Approach

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IEEE TRANSACTIONS ON PARALLEL AND DISTRIBUTED SYSTEMS 2024年第8期35卷 1345-1359页

作者： Ali, Isra M. Abdallah, Mohamed M. Hamad Bin Khalifa Univ Coll Sci & Engn Doha Qatar

The vulnerability of smart contracts has been demonstrated by an increasing number of multi-million exploitation incidents in public blockchains. Several works propose applying runtime verification to protect smart contracts post-deployment. However, none discuss the induced onchain overhead that may preclude its deployment, leaving smart contracts unprotected. A prominent solution to the onchain overhead is outsourcing the analysis off-chain. In this work, we analytically study the potential efficiency of off-chain smart contract runtime verification. We present a generic queueing network model of the off-chain runtime verification and the block generation process. The queuing model approach allows us to efficiently and flexibly capture the non-deterministic behavior of blockchain, estimating the number of transactions in the pool and their corresponding waiting times. We analyze the onchain overhead and evaluate off-chain RV, providing numerical indicators of transaction processing latency and throughput.

关键词： Blockchain concurrent execution offchain processing queue theory runtime verification smart contract

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An overview of blockchain smart contract execution mechanism

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JOURNAL OF INDUSTRIAL INFORMATION INTEGRATION 2024年 41卷

作者： Liu, Yang He, Jinlong Li, Xiangyang Chen, Jingwen Liu, Xinlei Peng, Song Cao, Haohao Wang, Yaoqi Henan Univ Technol Zhengzhou Peoples R China

Lacking a secure and reliable execution platform has hindered smart contracts from being applied in depth and width. Blockchain, as a decentralized, tamper-proof, and non-repudiation distributed computing platform, ensures that smart contracts are strictly enforced according to their established logic and not manipulated in the execution process. Programmability on the blockchain platforms is achieved through smart contracts to expand the application areas of blockchain extensively. However, current public blockchain and consortium blockchain platforms differ greatly in the execution mode of smart contracts, both of which have problems of how to execute smart contract efficiently and flexibly. This article provides a comparative analysis of mainstream blockchain platforms from the perspective of smart contracts execution mechanism, and summarizes the research status quo, challenges, and development trends from the perspective of smart contracts deployment and execution. We also discussed four perspectives on how smart contracts empower Industry 4.0 and explored the potential transition from digital industry to trusted industry through case studies. This article provides a distinct angle of view to survey smart contracts, which may count for the follow-up work of performance improvement for the blockchain platforms.

关键词： Blockchain Smart contracts Contract execution performance concurrent execution Parallel execution Industry 4.0

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SRP: An Efficient Runtime Protection Framework for Blockchain-based Smart Contracts

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JOURNAL OF NETWORK AND COMPUTER APPLICATIONS 2023年第1期216卷

作者： Ali, Isra M. Lasla, Noureddine Abdallah, Mohamed M. Erbad, Aiman Hamad Bin Khalifa Univ Coll Sci & Engn Ar Rayyan Qatar Natl Sch Artificial Intelligence ENSIA Mahelma Algeria

Runtime-verification of smart contracts ensures the absence of exploitations within a transaction during execution. It is a crucial security aspect that is often omitted due to its high onchain overhead. The lack of runtime-verification in public blockchains allowed attackers to compromise vulnerable contracts and cause significant monetary losses. Although several runtime protection solutions have been proposed, they do not discuss the onchain overhead limitation, which may hinder their deployment and undermine their effectiveness. To address this problem, we propose an efficient Smart contract Runtime Protection framework, called SRP, that minimizes the onchain burden of runtime-verification by integrating an off-chain mechanism with onchain contract execution. The proposed hybrid architecture is designed to protect already-deployed smart contracts from attacks in real-time while maintaining the throughput of the underlying blockchain. We first present SRP from a design perspective proposing a protocol customized for off-chain runtime-verification interoperability. Then, we evaluate our approach empirically and demonstrate the applicability of SRP using a proof-of-concept implementation on a local instance of the Ethereum network. Our empirical and experimental results indicate the feasibility and efficiency of our approach, where SRP outperforms the onchain-only mechanism in terms of service time and throughput, for increasing workloads.

关键词： Blockchain Smart contract Off-chain processing Runtime verification concurrent execution

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