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Unified Enclave Abstraction and Secure Enclave Migration on Heterogeneous Security Architectures

Journal of Computer Science & Technology 2022年第2期37卷 468-486页

作者： Jin-Yu Gu Hao Li Yu-Bin Xia Hai-Bo Chen Cheng-Gang Qin Zheng-Yu He Engineering Research Center for Domain-Specific Operating Systems Ministry of EducationShanghai 200240China Institute of Parallel and Distributed Systems Shanghai Jiao Tong UniversityShanghai 200240China Ant Group Hangzhou 310099China

ion and secure enclave migration on heterogeneous security architectures.

关键词： heterogeneous trusted execution environment(TEE) enclave abstraction enclave migration

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Modeling and analysis of sharing ratio enforcement in private BitTorrent communities

Modeling and analysis of sharing ratio enforcement in privat...

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2011 IEEE International Conference on Communications, ICC 2011

作者： Jia, Adele L. D'Acunto, Lucia Meulpolder, Michel Pouwelse, Johan A. Parallel and Distributed Systems Group Department of Computer Science Delft University of Technology Netherlands

ISBN: (纸本)9781612842332

Providing incentives for user contribution has been one of the primary design goals of Peer-to-Peer systems. The newly-emerged BitTorrent private communities adopt Sharing Ratio Enforcement (SRE) on top of BitTorrent's incentive mechanism, Tit-For-Tat, in order to strictly enforce a minimum contribution a member has to provide, in relation to the amount of service it has received. In this paper, we provide a theoretical model to analyze 1) how SRE provides seeding incentives, and 2) how SRE influences the download performance in the system. Specifically, we study the influence of the SRE threshold (i.e., the minimum sharing ratio requirement) and the bandwidth heterogeneity of the peers in the system. In our analysis, we assume users to be rational, i.e., peers seed only the minimum amount required by SRE, and we show that the download performance as predicted by our model represents a lower bound for the actual performance that can be reached in a BitTorrent private community. Hence, following our model, community administrators can predict the minimum performance level their systems will be able to reach. © 2011 IEEE.

关键词： Peer to peer networks

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Improving accuracy and coverage in an internet-deployed reputation mechanism

Improving accuracy and coverage in an internet-deployed repu...

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2010 IEEE 10th International Conference on Peer-to-Peer Computing, P2P 2010

作者： Delaviz, Rahim Andrade, Nazareno Pouwelse, Johan A. Parallel and Distributed Systems Group Department of Computer Science Delft University of Technology Netherlands

ISBN: (纸本)9781424471416

P2P systems can benefit from reputation mechanisms to promote cooperation and help peers to identify good service providers. However, in spite of a large number of proposed reputation mechanisms, few have been investigated in real situations. BarterCast is a distributed reputation mechanism used by our Internet-deployed Bittorent-based file-sharing client Tribler. In BarterCast, each peer uses messages received from other peers to build a weighted, directed subjective graph that represents the upload and download activity in the system. A peer calculates the reputations of other peers by applying the maxflow algorithm to its subjective graph. For efficiency reasons, only paths of at most two hops are considered in this calculation. In this paper, we identify and assess three potential modifications to BarterCast for improving its accuracy and coverage (fraction of peers for which a reputation value can be computed). First, a peer executes maxflow from the perspective of the node with the highest betweenness centrality in its subjective graph instead of itself. Second, we assume a gossiping protocol that gives each peer complete information about upload and download activities in the system, and third, we lift the path length restriction in the maxflow algorithm. To assess these modifications, we crawl the Tribler network and collect the upload and download actions of the peers for three months. We apply BarterCast with and without the modifications on the collected data and measure accuracy and coverage. ©2010 IEEE.

关键词： Peer to peer networks

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BitTorrent's dilemma: Enhancing reciprocity or reducing inequity

BitTorrent's dilemma: Enhancing reciprocity or reducing ineq...

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2011 IEEE Consumer Communications and Networking Conference, CCNC'2011

作者： Jia, Adele L. D'Acunto, Lucia Meulpolder, Michel Pouwelse, Johan A. Epema, Dick H. J. Parallel and Distributed Systems Group Department of Computer Science Delft University of Technology Netherlands

ISBN: (纸本)9781424487905

Enhancing reciprocity has been one of the primary motivations for the design of incentive policies in BitTorrent-like P2P systems. Reciprocity implies that peers need to contribute their bandwidth to other peers if they want to receive bandwidth in return. However, the over-provisioning that characterizes today's BitTorrent communities and the development of many next-generation P2P systems with real-time constraints (e.g., for live and on-demand streaming) suggest that more effort can be devoted to reducing the inequity (i.e., the difference of service received) among peers, rather than only enhancing reciprocity. Inspired by this observation, in this work we analyze in detail several incentive mechanisms that are used in BitTorrent systems, and explore several strategies that influence the balance between reciprocity and equity. Our study shows that (i) reducing inequity leads to a better overall system performance, and (ii) the behavior of seeders (i.e., peers that hold a complete copy of the file and upload it for free) influences whether reciprocity is enhanced or inequity reduced. © 2011 IEEE.

关键词： Bandwidth

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Balancing Tracking Granularity and parallelism in Many-Task systems: The Horizons Approach

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SN Computer Science 2024年第4期5卷 1-12页

作者： Thoman, Peter Salzmann, Philip Distributed and Parallel Systems Group University of Innsbruck Technikerstraße 21a Tirol Innsbruck 6020 Austria

Reducing the need for users to manually manage the details of work and data distribution is an important goal of high-level many-task runtime systems. For distributed memory platforms this means that the runtime system has to keep track of both fine-grained task dependencies and data residency meta-information. The amount of such meta-information is proportional to the granularity of parallelism which needs to be managed, introducing a trade-off. More precise tracking of data state allows leveraging more opportunities for compute and transfer parallelism, while also introducing more overhead. As such, the fidelity of the information being tracked needs to be managed carefully, ideally without introducing additional latency, communication or substantial compute overhead. We present the “Horizons” approach, designed to fulfill these goals. Specifically, horizons allow for the effective and efficient management of parallelism and the coalescing of previous fine-grained tracking information while maintaining an easily configurable scheduling window with full information precision. As an additional benefit, they provide consistent cluster-wide decision points without requiring any inter-node communication, and effectively cap the size of state tracking data structures even in the presence of problematic access patterns. Experimental evaluation on microbenchmarks and dry runs demonstrates that horizons are effective in keeping the scheduling complexity constant, while their own overhead is negligible—below 10μs per horizon when building a command graph for 512 GPUs. We additionally demonstrate the performance impact of horizons—as well as their low overhead—on a real-world application. © The Author(s) 2024.

关键词： Asynchronicity Command generation Dependency tracking Gpu cluster Task graph

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Towards semantic web services in grid environments

Towards semantic web services in grid environments

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1st International Conference on Semantics, Knowledge and Grid, SKG 2005

作者： Toma, Ioan Roman, Dumitru Iqbal, Kashif Fensel, Dieter Decker, Stefan Hofer, Juergen Galway Ireland Innsbruck Austria Distributed and Parallel Systems Group University of Innsbruck Innsbruck Austria

ISBN: (纸本)0769525342

Web services and Grid computing are technologies with a great impact these days. Both technologies are taking a syntactical based approach to describe services, and therefore, limited support is provided for service related tasks like: discovery, composition, etc. Semantic Web services try to overcome the limitations of syntactical based approaches by adding semantics to services descriptions. One of the most salient initiatives in Semantic Web services area is the Web Service Modeling Ontology (WSMO). WSMO provides a conceptual model and languages to express semantic, descriptions of services. We believe that WSMO, the conceptual model, and WSML, the associated family of languages, with some extensions and/or restrictions could be the solution for semantically describe services in Grid environment. © 2006 IEEE.

关键词： Grid computing

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The otho toolkit: Generating tailor-made scientific grid application wrappers

The otho toolkit: Generating tailor-made scientific grid app...

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2nd International Conference on Grid Service Engineering and Management, GSEM 2005 - Co-located with the 6th International Conference on Net.ObjectDays 2005, NODe 2005

作者： Hofer, Juergen Villazón, Alex Siddiqui, Mumtaz Fahringer, Thomas Distributed and Parallel Systems Group University of Innsbruck Technikerstrasse 21a 6020 Innsbruck Austria

ISBN: (纸本)3885793989

Grid technologies and middleware components have shorter lifecycles than most scientific applications. The smooth and automatic migration of existing codes to modern environments continues to be a major research issue. In our work we address this problem from a novel perspective (MDA) and for a specific problem domain (scientific grid applications). We demonstrate how we apply results and techniques from the Model-driven Architecture and Code Generation fields to automatically create Scientific Grid Application Wrappers in form of different types of services among them plain Web services or WSRF services. The wrappers are enriched with non-functional property extensions such as performance analysis, resource-accounting, file-staging or execution management for instance. Design and implementation of our prototype with accounting of CPU consumption as non-functional property is exhibited. The "Invisible Grid" is an ideal Grid environment where users are completely shielded from any Grid specific details. Our research is ongoing work. We present our archievements so far on getting one step closer towards this vision.

关键词： Web services

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Optimizing embedded industrial safety systems based on time-of-flight depth imaging 17

Optimizing embedded industrial safety systems based on time-...

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17th IEEE International Conference on eScience, eScience 2021

作者： Thoman, Peter Hirsch, Alexander Wippler, Markus Hranitzky, Robert University of Innsbruck Distributed and Parallel Systems Group Austria Tofmotion GmbH Vienna1120 Austria

ISBN: (纸本)9781665403610

Time-of-flight camera systems provide rapid, low-latency depth imaging. In the context of industrial safety, they can be employed to replace costly and inflexible physical safety installations with virtual safety volumes, monitored by time-of-flight cameras which turn off dangerous systems when unknown objects enter specified bounding *** this context, the 3D point-shape collision detection algorithm has to be highly optimized for very specific goals. These include high real-time (worst case) performance, low power consumption and acceptable thermal characteristics, ideally with low-cost and well-established embedded *** present our work in the INPACT project, which explores various algorithmic and parallelization-based methods of improving the performance, responsiveness and reliability of such systems. Our experiments are are based on a setup allowing long-term measurement of multiple thermal sampling points as well as fine-grained power consumption information and of course performance and throughput metrics. © 2021 IEEE.

关键词： Accident prevention

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On the performance variability of production cloud services 11

On the performance variability of production cloud services

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Proceedings of the 2011 11th IEEE/ACM International Symposium on Cluster, Cloud and Grid Computing

作者： Iosup, Alexandru Yigitbasi, Nezih Epema, Dick Parallel and Distributed Systems Group Delft University of Technology Mekelweg 4 2628 CD Delft Netherlands

ISBN: (纸本)9780769543956

Cloud computing is an emerging infrastructure paradigm that promises to eliminate the need for companies to maintain expensive computing hardware. Through the use of virtualization and resource time-sharing, clouds address with a single set of physical resources a large user base with diverse needs. Thus, clouds have the potential to provide their owners the benefits of an economy of scale and, at the same time, become an alternative for both the industry and the scientific community to self-owned clusters, grids, and parallel production environments. For this potential to become reality, the first generation of commercial clouds need to be proven to be dependable. In this work we analyze the dependability of cloud services. Towards this end, we analyze long-term performance traces from Amazon Web Services and Google App Engine, currently two of the largest commercial clouds in production. We find that the performance of about half of the cloud services we investigate exhibits yearly and daily patterns, but also that most services have periods of especially stable performance. Last, through trace-based simulation we assess the impact of the variability observed for the studied cloud services on three large-scale applications, job execution in scientific computing, virtual goods trading in social networks, and state management in social gaming. We show that the impact of performance variability depends on the application, and give evidence that performance variability can be an important factor in cloud provider selection. © 2011 IEEE.

关键词： Web services

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Leveraging C++ Meta-programming Capabilities to Simplify the Message Passing Programming Model

Leveraging C++ Meta-programming Capabilities to Simplify the...

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18th European MPI Users’ group Meeting, EuroMPI 2011

作者： Pellegrini, Simone Prodan, Radu Fahringer, Thomas University of Innsbruck – Distributed and Parallel Systems Group Technikerstr. 21A Innsbruck6020 Austria

ISBN: (纸本)9783642244483

Message passing is the primary programming model utilized for distributed memory systems. Because it aims at performance, the level of abstraction is low, making distributed memory programming often difficult and error-prone. In this paper, we leverage the expressivity and meta-programming capabilities of the C++ language to raise the abstraction level and simplify message passing programming. We redefine the semantics of the assignment operator to work in a distributed memory fashion and leave to the compiler the burden of generating the required communication operations. By enforcing more severe checks at compile-time we are able to statically capture common programming errors without causing runtime overhead. © Springer-Verlag Berlin Heidelberg 2011.

关键词： Message passing

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