Seminarium: Systemy Rozproszone
16 października 2025 12:15, transmisja online
Tomasz Kubica, Franciszek Stachura



Evaluation of libfabric performance in comparison with direct ibverbs implementations



Modern HPC applications rely on efficient communication. The primary goals are minimizing latency and maximizing network bandwidth. To help achieve these goals, programming frameworks should have the lowest overhead possible. Libfabric is a low-level communication library that provides an abstraction over various networking technologies. Libfabric supports multiple communication systems including Infiniband, RoCE and Omni-Path. Applications developed with libfabric can be run on different systems. As such, libfabric can drastically improve portability and ease of use for HPC systems and libraries such as MPI implementations, parallel computing frameworks, and serverless systems. However, the API of libfabric differs significantly from other libraries, and the documentation lacks tips on performance optimizations.

Zapraszam,
Tomasz Kubica





Efficient Network Flooding and Time Synchronization with Glossy



This paper presents Glossy, a novel flooding architecture for wireless sensor networks. Glossy exploits constructive interference of IEEE 802.15.4 symbols for fast network flooding and implicit time synchronization. We derive a timing requirement to make concurrent transmissions of the same packet interfere constructively, allowing a receiver to decode the packet even in the absence of capture effects. To satisfy this requirement, our design temporally decouples flooding from other network activities. We analyze Glossy using a mixture of statistical and worst-case models, and evaluate it through experiments under controlled settings and on three wireless sensor testbeds. Our results show that Glossy floods packets within a few milliseconds and achieves an average time synchronization error below one microsecond. In most cases, a node receives the flooding packet with a probability higher than 99.99 %, while having its radio turned on for only a few milliseconds during a flood. Moreover, unlike existing flooding schemes, Glossy’s performance exhibits no noticeable dependency on node density, which facilitates its application in diverse real-world settings. During my presentation, I will describe Glossy in detail and talk about the 1KT testbed, this time focusing on the wireless sensor node - the TI CC2650 microcontroller.

Zapraszam,
Franciszek Stachura



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