UWSpace

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Recent Submissions

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    The Cognitive-Affective Model of Sexual Consent Communication
    (University of Waterloo, 2026-08-04) Edwards, Jessica
    Sexual consent communication involves direct, unambiguous communication about willingness to participate in sexual encounters; promoting this form of communication is important to reducing sexual coercion and promoting the quality of sexual relationships. The present studies introduce and evaluate the Cognitive-Affective Model of Sexual Consent Communication, which is proposed to identify intrapersonal precursors (i.e., attachment insecurity) and mechanisms (i.e., perspective-taking, emotion dysregulation, experiential avoidance) that influence how adequately people communicate sexual consent. The model also indicates that these factors predict sexual consent motivations, an important precursor to the decision to enact affirmative consent behaviours. In Study 1 (N = 153), I examined the associations between core constructs of the model for people in current sexual relationships, finding that attachment, perspective-taking skill, and emotion regulation skill are associated with consent motivations and consent communication behaviours in existing sexual relationships. Study 2 included the piloting of a novel, vignette-based measure of sexual consent communication behaviour (Study 2a; N = 97), and testing of the key mediational pathways in a sample of single adults with this measure (Study 2b; N = 173). Results indicated support for the cognitive pathway of the model, but did not support the role of experiential avoidance in predicting consent motivations/behaviour. Finally, Study 3 (N = 212) tested the effects of a brief psychoeducational perspective-taking intervention on participants’ sexual consent motivations and behaviours. Outcome variables were assessed using the same vignette measure as Study 2, but participant responses were audio-recorded to extract more information about the emotional tone of consent communication. The intervention did not produce changes in consent communication behaviour relative to control, but sexual consent motivations were higher following the intervention for the subset of participants who reported low attachment avoidance. Taken together, the results of these studies illustrate the importance of moving beyond skills instruction to incorporate psychological traits and skills in consent education. Furthermore, the current research sheds light on the potential benefits of reducing perceived emotional threat in consent communication while enhancing perceptions of consent as rewarding and beneficial.
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    Lanternfish: Better random networks through optics
    (University of Waterloo, 2015-07-23) Szepesi, Tyler; Wond, Bernard; Kazhami, Fiodar; Rizvi, Sajjad; Brecht, Tim
    Current random datacenter network designs, such as Jellyfish, directly wire top-of-rack switches together randomly, which is difficult even when using best-practice cable management techniques. Moreover, these are static designs that cannot adapt to changing workloads. In this paper, we introduce Lanternfish, a new approach to building random datacenter networks using an optical ring that significantly reduces wiring complexity and provides the opportunity for reconfigurability. Unlike previous optical ring designs, Lanternfish does not require wavelength planning because it is specifically designed to provide random connectivity between switches. This design choice further reduces the difficulty of deploying a Lanternfish network, making random datacenter networks more practical. Our experimental results using both simulations and network emulation show that Lanternfish can effectively provide the same network properties as Jellyfish. Additionally, we demonstrate that by replacing passive optical components with active optical components at each switch, we can dynamically reconfigure the network topology to better suit the workload while remaining cost competitive. Lanternfish is able to construct workload specific topologies that provide as much as half the average pathlength than a Jellyfish deployment with twice as many switch-to-switch connections.
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    Mayflower: Improving distributed filesystem performance through SDN/filesystem co-design
    (University of Waterloo, 2015-07-23) Rizvi, Sajjad; Li, Xi; Wong, Bernard; Cao, Xiao; Cassell, Benjamin
    The increasing prevalence of oversubscribed networks and fast solid-state storage devices in the datacenter has made the network the new performance bottleneck for many distributed filesystems. As a result, distributed filesystems need to be network-aware in order to make more effective use of available network resources. In this paper, we introduce Mayflower, a new distributed filesystem that is not only network-aware, it is co-designed from the ground up to work together with a network control plane. In addition to the standard distributed filesystem components, Mayflower has a flow monitor and manager running inside a software-defined networking controller. This tight coupling with the network controller enables Mayflower to make intelligent replica selection and flow scheduling decisions based on both filesystem and network information. It also enables Mayflower to perform global optimizations that are unavailable to conventional distributed filesystems and network control planes. Our evaluation results from both simulations and a prototype implementation show that Mayflower reduces average read completion time by more than 25% compared to current state-of-the-art distributed filesystems with an independent network flow scheduler, and more than 80% compared to HDFS with ECMP.
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    Nessie: A decoupled, client-driven, key-value store using RDMA
    (University of Waterloo, 2015-07-22) Szepesi, Tyler; Cassell, Benjamin; Wong, Bernard; Brecht, Tim; Liu, Xiaoyi
    The increasing use of key-value storage systems in performance-critical data centre applications has motivated new storage system designs that use Remote Direct Memory Access (RDMA) to reduce communication overhead. However, existing approaches that achieve low latency and high throughput do so by dedicating entire cores to PDMA message handling, including polling local memory for incoming RDMA messages. In this paper we describe and demonstrate why polling-based RDMA is not suitable for many data centre applications with significant data processing and data storage requirements. We then propose, design, implement and evaluate an alternative communication approach that strictly uses one-sided RDMA operations, which eliminates polling on the server-side and is therefore a serverless (client-driven) design. This approach is used to build Nessie, a distributed client-driven RDMA-enabled key-value store that uses native RDMA compare-and-swap operations to co-ordinate conflicting operations between clients. Nessie further reduces communication requirements by decoupling the key-value location from the key lookup mechanism, which enables local write operations, thus avoiding comparatively expensive RDMA operations. Nessie's one-sided design ensures that only the clients in the system consume any CPU, which in turn allows it to maintain high performance despite the need for computation by the application utilizing the key-value store or contention from other applications.
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    CrossStitch: An efficient transaction processing framework for geo-distributed system
    (University of Waterloo, 2015-07-28) Choy, Sharon; Wong, Bernard; Cui, Xu; Liu, Xiaoyi
    Current transaction system for geo-distributed datastores either have high transaction processing latencies or are unable to support general transactions with dependent operations. In this paper, we introduce CrossStitch, an efficient transaction processing framework that reduces latency by restructuring each transaction into a chain of state transitions, where each state consists of a key operation and computation. Transaction states are processed sequentially, and the transaction code and data is sent directly to the next hop in the chain. CrossStitch transactions can be organized such that all states in a location are processed before transitioning to a state in a different location. This allows CrossStitch to significantly reduce the number of inter-location crossings compared to transaction systems that retrieve remote data to a single location for processing. To provide transactional properties while preserving the chain communication pattern, CrossStitch introduces a pipelined commit protocol that executes in parallel with the transaction and does not require any centralized co-ordination. Our evaluation results show that CrossStitch can reduce the latency of geo-distributed transactions when compared to a traditional 2PC-based distributed transaction system. We demonstrate that CrossStitch can reduce the number of round trips by more than half for TPC-C-like transactions.