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ESDU: An elastic stripe-based delta update method for erasure-coded cross-data center storage systems

JOURNAL OF parallel AND distributed COMPUTING 2022年第0期167卷 173-186页

作者： Bao, Han Wang, Yijie Natl Univ Def Technol Sch Comp Natl Lab Parallel & Distributed Proc Changsha 410073 Peoples R China

The erasure-coded cross-data center storage system can achieve high disaster tolerance and low redundancy. But as it has large cross-data center update traffic, its data update time is long. In erasure-coded storage systems, each data object is sequentially divided into several stripes, and each stripe consists of several data packets. When erasure-coded stripes do not undergo insertion or deletion, existing work can effectively reduce cross-data center update traffic by performing delta updates- delta update methods can update the old stripe without transferring matched packets that are new and old stripes' duplicate packets with the same offset-within-stripe. However, because existing delta update methods' stripe size is fixed, when a stripe undergoes insertion or deletion, its subsequent stripes' duplicate packets' offset-within-stripe will change. In this scenery, the matched packet number is small, resulting in large cross-data center update traffic. This paper proposes an elastic stripe-based delta update method for erasure-coded cross-data center storage systems (ESDU). Under insertion or deletion, ESDS tries to avoid duplicate packets' offset-within-stripe changing (i.e., maximizing matched packets) by adjusting the stripes' size flexibly according to the duplicate packet locating result. So, it can reduce cross-data center traffic. Moreover, ESDU can optimize stripes' update topology based on the location information of storage nodes to reduce cross-data center update traffic further. In addition, we implement an erasure-coded cross-data center storage system adopting ESDU, called ECESD. Experiments with the workloads derived from EduCoder's real-world trace show that compared with the existing erasure-coded cross-data center storage system adopting the fixed stripe-based delta update method, ECESD reduces average update time by 89.6%. Moreover, compared with a replication-based storage system with a delta update method (HadoopRsync), ECESD achieves an 8.3%

关键词： Erasure code Disaster tolerance distributed storage system Delta update method Cross-data center storage

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Sampling Policies for Near-Optimal Device Choice in parallel Simulations on CPU/GPU Platforms 28

Sampling Policies for Near-Optimal Device Choice in Parallel...

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28th IEEE/ACM International Symposium on distributed Simulation and real time Applications, DS-RT 2024

作者： Andelfinger, Philipp Pellegrini, Alessandro Marotta, Romolo University of Rostock Germany Tor Vergata University of Rome Italy

ISBN: (纸本)9798331527211

Heterogeneous hardware platforms comprised of CPUs, GPUs, and other accelerators offer the opportunity to choose the best-suited device for executing a given scientific simulation in order to minimize execution time and energy consumption. To this end, the recently proposed "Follow the Leader"approach dynamically selects a suitable device based on runtime performance measurements during speculative discrete-event simulations. A currently active "leader"device is periodically challenged by a "follower"device in order to negotiate the new leader. The optimality of the device choices and the associated overhead depends critically on the challenge frequency and timing. Here, we explore policies to schedule challenges with the goal of attaining Pareto-optimal combinations of execution time and energy consumption. Several heuristics are first evaluated in an abstract fashion using a "meta-simulation"by mimicking the progress and energy consumption of an idealized co-execution. In this setting, we optimize the heuristics' tuning parameters to assess their relative merits in near-optimal configurations when compared to challenge timings based on perfect knowledge. We find that under challenging stochastic workloads based on a class of mean-reverting random walks, the best heuristics can closely approximate the execution time and energy consumption achievable under an optimal device choice. Empirical support for this observation is given by measurements of a CPU/GPU co-execution of the time Warp algorithm on physical hardware. © 2024 IEEE.

关键词： Stochastic systems

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Integrating parallel, Tensor-Based Computing in Agent-Based Simulators

Integrating Parallel, Tensor-Based Computing in Agent-Based ...

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International workshop/Symposium on distributed Simulation and real-time Applications (DS-RT)

作者： Nikitas M. Sgouros Department of Digital Systems University of Piraeus Piraeus Greece

The rise of deep learning methods has ignited interest in efficient hardware and software systems for tensor-based computing. A question worth investigating is whether other areas in computing can benefit as well from the power and increasing availability of such systems. To this end, we study the integration of tensor-based techniques in agent-based simulators. In particular, we describe methods for the representation as vectors of agent and edge attributes in agent networks and the compilation of rules governing agent behavior and their edge-based interactions into functions that can process and compute such attribute vectors in parallel. We describe a proof of concept implementation of such an idea in Politika, our Elixir-based web framework for concurrent, agent-based simulation. We discuss various simulation scenarios for our implementation and provide directions for future optimizations and integration pathways with concurrent simulation environments.

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OptimizeLog: Log Anomaly Detection and Localization based on Optimized Log Parsing in distributed systems 9

OptimizeLog: Log Anomaly Detection and Localization based on...

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9th International Conference on Computer and Communications, ICCC 2023

作者： Sun, Yanjie Gao, Yali Li, Xiaoyong Ministry of Education Beijing China

ISBN: (纸本)9798350317251

Modern distributed systems generate interleaved logs when performing parallel operations, and these logs become an important basis for anomaly detection and localization. To achieve more robust and accurate log anomaly detection and localization, we propose a comprehensive model, namely OptimizeLog. We built a dictionary- and length-based log parser that works stably in most log systems without parameter tuning. We significantly improve anomaly detection accuracy by introducing ALBERT-based semantic embeddings, count embeddings, and time embeddings, combined with an attentionbased Bi-GRU model. By constructing component instance forest and tree-based depth-first traversal algorithm, abnormal location in distributed systems is realized. Experimental results show that our log parsing method is 4% more accurate than other log parsers. Compared with other advanced methods such as DeepLog, LogAnomaly, and LogRobust, OptimizeLog improves the accuracy of anomaly detection by 5%, while enabling instancelevel anomaly localization on real datasets. © 2023 IEEE.

关键词： Anomaly detection

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Decarbonisation demands decentralisation: How blockchain is impacting the energy sector

Decarbonisation demands decentralisation: How blockchain is ...

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CIRED 2024 Vienna workshop

作者： Manea, Andrei Nicolas Akoury-Shima, Marellie Bhandari, Vivek Stammler, Jakob Linus DNV Energy Systems One Linear Park Bristol United Kingdom Powerledger Dammstrasse 16 Zug Switzerland

ISBN: (纸本)9781837242672

In the transition to a society with net-zero carbon emissions, high penetration of renewable energy sources and novel energy vectors are driving traditional operational systems, models, and processes towards emerging digital solutions that facilitate the changes occurring in the energy sector. As a radical shift to decentralisation and digitalisation unfolds, blockchain technology emerges as a key enabler of this transformation. This paper provides a comprehensive analysis of the evolving role and potential of blockchain in supporting the energy sector's move to a more sustainable, efficient, and transparent system. Through the lens of blockchain's capabilities, this paper explores how this technology can address the challenges of a rapidly digitalising energy landscape and offer a strategic advantage in the transition to a net-zero future. Specifically, blockchain facilitates increased hosting capacity by enabling dynamic interactions between distributed energy resources and the grid, ensuring real-time management and optimisation. This capability directly supports the grid in accommodating larger volumes of renewable sources without the need for extensive physical upgrades. © The Institution of Engineering & Technology 2024.

关键词： distributed ledger

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A Wireless-Communication Based Circulating-Current Controller for parallel Three-Phase Inverters 23

A Wireless-Communication Based Circulating-Current Controlle...

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IEEE 23rd workshop on Control and Modeling for Power Electronics (COMPEL)

作者： Acharya, Kaustuva Mazumder, Sudip K. Tahir, Muhammad Amazon Bellevue WA USA Univ Illinois Dept Elect & Comp Eng Chicago IL 60607 USA Univ Engn & Technol Dept Eectr Engn Lahore 54890 Pakistan

ISBN: (纸本)9781665410816

We propose a circulating-current control scheme for a two-module parallel three-phase voltage-source inverter (VSI) that can be applied in general to any space-vector modulation (SVM) scheme and experimentally demonstrate its effectiveness for two commonly used SVM schemes (symmetrical SVM and bus-clamped SVM). The proposed control strategy relies on radiofrequency (RF) based wireless communication to exchange circulating-current information among the parallel VSIs. We also investigate the impacts of time delay due to wireless communication on the stability of the parallel VSI. Thus, by transmitting the circulating-current information over a wireless medium, we attain improved VSI performance, while also ensuring that the issues of survivability, robustness, self-configuration and reconfigurability of the system are not compromised. In general, such a control scheme may lead to more redundant control implementation of distributed power systems and could also be used as a back-up for wire-based control schemes to provide fault tolerance.

关键词： Support vector machines Wireless communication Radio frequency Fault tolerant systems Modulation Power system stability Inverters

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Targeting a light-weight and multi-channel approach for distributed stream processing

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JOURNAL OF parallel AND distributed COMPUTING 2022年 167卷 77-96页

作者： Venugopal, Vinu Ellampallil Theobald, Martin Tassetti, Damien Chaychi, Samira Tawakuli, Amal Int Inst Informat Technol Bangalore India Univ Luxembourg Esch Sur Alzette Luxembourg Univ Nantes Nantes France

Processing high-throughput data-streams has become a major challenge in areas such as real-time event monitoring, complex dataflow processing, and big data analytics. While there has been tremendous progress in distributed stream processing systems in the past few years, the high-throughput and low latency (a.k.a. high sustainable-throughput) requirement of modern applications is pushing the limits of traditional data processing infrastructures. This paper introduces a new distributed stream processing engine (DSPE), called Asynchronous Iterative Routing (or simply "AIR "), which implements a light-weight, dynamic sharding protocol. AIR expedites direct and asynchronous communication among all the worker nodes via a channel-like communication protocol on top of the Message Passing Interface (MPI), thereby completely avoiding the need for a dedicated driver node. The system adopts a new progress-tracking protocol, called hew-meld, which has been experimentally observed to show a low processing latency on our asynchronous master-less architecture when compared to the conventional low-watermark technique. The current version of AIR is also equipped with two fault tolerance and recovery strategies namely checkpointing & rollback and replication. With its unique design, AIR scales out particularly well to multi core HPC architectures;specifically, we deployed it on clusters with up to 16 nodes and 448 cores (thus reaching a peak of 435.3 million events and 55.14 GB of data processed per second), which we found to significantly outperform existing DSPEs. (c) 2022 Elsevier Inc. All rights reserved.

关键词： distributed stream processing systems Dataflow programming Asynchronous iterative routing Stateful windowed operators

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real-time Routing in Traffic Simulations: A distributed Event Processing Approach

Real-Time Routing in Traffic Simulations: A Distributed Even...

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International Symposium on parallel and distributed Computing

作者： Paul Heinrich Janek Laudan Kai Nagel Transport Systems Planning and Transport Telematics Technical University of Berlin Germany

ISBN: (数字)9798350369199

ISBN: (纸本)9798350369205

This paper explores the integration of distributed event processing in the context of real-time routing within a parallel transportation simulation framework for the Multi-Agent Transport Simulation (MATSim). A novel simulation prototype, utilizing Rust and MPI, demonstrates significant re-ductions in computation time by applying domain decomposition of the network and assigning each part to a separate process. However, sharing and processing events within this setup remains challenging. We present a proof of concept for integrating distributed event processing. Our evaluation has shown that realtime routing significantly increases simulation runtime because uneven distribution of routing requests increases load imbalances and makes speedups less efficient. Sharing event data between processes benefits from smaller subdomains. However, global synchronization for sharing data leads to waiting times introduced by load imbalances.

关键词： Runtime Transportation Prototypes Information sharing Routing real-time systems Synchronization distributed computing

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Towards an Optimized Heterogeneous distributed Task Scheduler in OpenMP Cluster

Towards an Optimized Heterogeneous Distributed Task Schedule...

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2024 workshops of the International Conference for High Performance Computing, Networking, Storage and Analysis, SC workshops 2024

作者： Neveu, Remy Ceccato, Rodrigo Leite, Gustavo Araujo, Guido Diaz, Jose M. Monsalve Yviquel, Herve Instituto de Computação Campinas Brazil

ISBN: (纸本)9798350355543

This paper addresses the challenges of optimizing task scheduling for a distributed, task-based execution model in OpenMP for cluster computing environments. Traditional OpenMP implementations are primarily designed for shared-memory parallelism and offer limited control over task scheduling. However, improved scheduling mechanisms are critical to achieving performance and portability in distributed and heterogeneous environments. OpenMP Cluster (OMPC) was introduced to overcome these limitations, extending OpenMP with the Heterogeneous Earliest Finish time (HEFT) task scheduling algorithm tailored for large-scale systems. To improve scheduling and enable better system utilization, the runtime system must resolve challenges such as changes in the application balance, amount of parallelism, and varying communication *** work presents three key contributions: first, the refactoring of the OMPC runtime to unify task scheduling across devices and hosts;second, the optimization of the HEFT-based scheduling algorithm to ensure efficient task execution in distributed environments;and third, an extensive evaluation of Work Stealing and HEFT scheduling mechanisms in real-world clusters. While the HEFT implementation in OMPC is not fully optimized, this work provides a significant step toward improving distributed task scheduling in cluster computing, offering insights and incremental advancements that support the development of scalable and high-performance applications. Results show improvements of up to 24% in scheduling time while opening up to more extensions in the scheduling methods. © 2024 IEEE.

关键词： distributed architectures parallel systems Scheduling and task partitioning

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DHR: distributed Hybrid Rendering for Metaverse Experiences 1

DHR: Distributed Hybrid Rendering for Metaverse Experiences

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1st workshop on Interactive eXtended reality, IXR 2022

作者： Tan, Yu Wei Tan, Alden Nge, Nicholas Bhojan, Anand National University of Singapore Singapore Singapore

ISBN: (纸本)9781450395014

Classically, rasterization techniques are performed for real-time rendering to meet the constraint of interactive frame rates. However, such techniques do not produce realistic results as compared to ray tracing approaches. Hence, hybrid rendering has emerged to improve the graphics fidelity of rasterization with ray tracing in real-time. We explore the approach of distributed rendering in incorporating real-time hybrid rendering into metaverse experiences for immersive graphics. In standalone extended reality (XR) devices, such ray tracing-enabled graphics is only feasible through pure cloud-based remote rendering systems that rely on low-latency networks to transmit real-time ray-traced data in response to interactive user input. Under high network latency conditions, remote rendering might not be able to maintain interactive frame rates for the client, adversely affecting the user experience. We adopt hybrid rendering via a distributed rendering approach by integrating ray tracing on powerful remote hardware with raster-based rendering on user access devices. With this hybrid approach, our technique can help standalone XR devices achieve ray tracing-incorporated graphics and maintain interactive frame rates even under high-latency conditions. © 2022 Owner/Author.

关键词： Ray tracing

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