HASLab - Indexed Articles in Conferences

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Browsing HASLab - Indexed Articles in Conferences by Author "5602"
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    Adaptive database synchronization for an online analytical cioud-to-edge continuum
    ( 2022) Costa,D ; José Orlando Pereira ; Ricardo Pereira Vilaça ; Faria,N ; 5635 ; 5602
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    AIDA-DB: A Data Management Architecture for the Edge and Cloud Continuum
    ( 2022) Faria,N ; Costa,D ; José Orlando Pereira ; Ricardo Pereira Vilaça ; Ferreira,L ; Fábio André Coelho ; 6059 ; 5635 ; 5602
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    BDUS: implementing block devices in user space
    ( 2021) José Orlando Pereira ; João Tiago Paulo ; Alberto Campinho Faria ; Ricardo Gonçalves Macedo ; 7204 ; 6941 ; 5621 ; 5602
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    Black-box inter-application traffic monitoring for adaptive container placement
    ( 2020) Francisco Teixeira Neves ; Ricardo Pereira Vilaça ; José Orlando Pereira ; 6125 ; 5602 ; 5635
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    An Experimental Evaluation of Tools for Grading Concurrent Programming Exercises
    ( 2023) José Orlando Pereira ; Paulo Sérgio Almeida ; Alcino Cunha ; 5602 ; 5607 ; 5612
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    Horus: Non-Intrusive Causal Analysis of Distributed Systems Logs
    ( 2021) Machado,N ; 6125
    Logs are still the primary resource for debugging distributed systems executions. Complexity and heterogeneity of modern distributed systems, however, make log analysis extremely challenging. First, due to the sheer amount of messages, in which the execution paths of distinct system components appear interleaved. Second, due to unsynchronized physical clocks, simply ordering the log messages by timestamp does not suffice to obtain a causal trace of the execution. To address these issues, we present Horus, a system that enables the refinement of distributed system logs in a causally-consistent and scalable fashion. Horus leverages kernel-level probing to capture events for tracking causality between application-level logs from multiple sources. The events are then encoded as a directed acyclic graph and stored in a graph database, thus allowing the use of rich query languages to reason about runtime behavior. Our case study with TrainTicket, a ticket booking application with 40 microservices, shows that Horus surpasses current widely-adopted log analysis systems in pinpointing the root cause of anomalies in distributed executions. Also, we show that Horus builds a causally-consistent log of a distributed execution with much higher performance (up to 3 orders of magnitude) and scalability than prior state-of-the-art solutions. Finally, we show that Horus' approach to query causality is up to 30 times faster than graph database built-in traversal algorithms.
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    PAIO: General, Portable I/O Optimizations With Minor Application Modifications
    ( 2022) Ricardo Gonçalves Macedo ; Tanimura,Y ; Haga,J ; Chidambaram,V ; José Orlando Pereira ; João Tiago Paulo ; 5621 ; 6941 ; 5602
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    Taming Metadata-intensive HPC Jobs Through Dynamic, Application-agnostic QoS Control
    ( 2023) Ricardo Gonçalves Macedo ; José Orlando Pereira ; 6941 ; 5602
    Modern I/O applications that run on HPC infrastructures are increasingly becoming read and metadata intensive. However, having multiple applications submitting large amounts of metadata operations can easily saturate the shared parallel file system's metadata resources, leading to overall performance degradation and I/O unfairness. We present PADLL, an application and file system agnostic storage middleware that enables QoS control of data and metadata workflows in HPC storage systems. It adopts ideas from Software-Defined Storage, building data plane stages that mediate and rate limit POSIX requests submitted to the shared file system, and a control plane that holistically coordinates how all I/O workflows are handled. We demonstrate its performance and feasibility under multiple QoS policies using synthetic benchmarks, real-world applications, and traces collected from a production file system. Results show that PADLL can enforce complex storage QoS policies over concurrent metadata-aggressive jobs, ensuring fairness and prioritization.
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    Totally-Ordered Prefix Parallel Snapshot Isolation
    ( 2021) Nuno Filipe Faria ; José Orlando Pereira ; 5602 ; 8253
    Distributed data management systems have increasingly been using variants of Snapshot Isolation (SI) as their transactional isolation criteria as it combines strong ACID guarantees with non-blocking reads and scalability. However, most existing proposals are limited by the performance of update propagation and stability detection, in particular, when execution and storage are disaggregated. In this paper, we propose TOPSI, an approach providing a restricted form of Parallel Snapshot Isolation (PSI) that allows partially ordering recent transactions to avoid waiting for remote updates or using a stale snapshot. Moreover, it has the interesting property of making a prefix of history in all sites converge to a common total order. This allows versions to be represented by a single scalar timestamp for certification and storage in a shared store. We demonstrate the impact on throughput and abort rate with a proof-of-concept implementation and the industry-standard TPC-C benchmark. © 2021 ACM.
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    Towards Adaptive Transactional Consistency for Georeplicated Datastores
    ( 2025) José Orlando Pereira ; Fábio André Coelho ; 5602 ; 6059
    Developers of data-intensive georeplicated applications face a difficult decision when selecting a database system. As captured by the CAP theorem, CP systems such as Spanner provide strong consistency that greatly simplifies application development. AP systems such as AntidoteDB providing Transactional Causal Consistency (TCC), ensure availability in face of network partitions and isolate performance from wide-area round-trip times, but avoid lost-update anomalies only when values can be merged. Ideally, an application should be able to adapt to current data and network conditions by selecting which transactional consistency to use for each transaction. In this paper, we test the hypothesis that a georeplicated database system can be built at its core providing only TCC, hence, being AP, but allow an application to execute some transactions under Snapshot Isolation (SI), hence CP. Our main result is showing that this can be achieved even when all the interaction happens through the TCC database system, without additional communication channels between the participants. A preliminary experimental evaluation with a proof-of-concept implementation using AntidoteDB shows that this approach is feasible. Copyright © 2025 held by the owner/author(s).
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    Towards Generic Fine-Grained Transaction Isolation in Polystores
    ( 2021) Nuno Filipe Faria ; José Orlando Pereira ; Ana Nunes Alonso ; Ricardo Pereira Vilaça ; 8253 ; 5692 ; 5635 ; 5602
    Transactional isolation is a challenge for polystores, as along with the limited capabilities of each datastore, we have to contend with their sheer diversity. However, transactional isolation is increasingly desirable as a variety of datastores are being sought after for roles that go beyond data lakes. Transactional guarantees are also relevant for reliability at scale. In this paper, we propose that transactional isolation in polystores can be achieved by leveraging the query engine, i.e., basing some of the responsibilities of a traditional transactional storage manager (TSM) on the query language itself. This has the key advantage of greatly simplifying design and implementation, as it doesn’t need to be re-invented for each datastore, and should increase performance, by taking advantage of dynamic query optimization where available. We demonstrate the feasibility of the proposal with a simple proof-of-concept and experiment. © 2021, Springer Nature Switzerland AG.
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    TRUSTFS: An SGX-enabled Stackable File System Framework
    ( 2019) João Tiago Paulo ; José Orlando Pereira ; Bernardo Luís Portela ; Ricardo Gonçalves Macedo ; Alberto Campinho Faria ; Tânia Conceição Araújo ; 5621 ; 5602 ; 6060 ; 6941 ; 7204 ; 7401
    Data confidentiality in cloud services is commonly ensured by encrypting information before uploading it. However, this approach limits the use of content-aware functionalities, such as deduplication and compression. Although this issue has been addressed individually for some of these functionalities, no unified framework for building secure storage systems exists that can leverage such operations over encrypted data. We present TRUSTFS, a programmable and modular stackable file system framework for implementing secure content-aware storage functionalities over hardware-assisted trusted execution environments. This framework extends the original SAFEFS architecture to provide the isolated execution guarantees of Intel SGX. We demonstrate its usability by implementing an SGX-enabled stackable file system prototype while a preliminary evaluation shows that it incurs reasonable performance overhead when compared to conventional storage systems. Finally, we highlight open research challenges that must be further pursued in order for TRUSTFS to be fully adequate for building production-ready secure storage solutions.