Title: A Throughput Model for Data Stream Processing on Fog Computing
Speaker: Felipe Rodrigo de Souza (LIP, AVALON team)
Location: LIP, Meeting room M7 3rd floor
Today’s society faces an unprecedented deluge of data that requires processing and analysis. Data Stream Processing (DSP) applications are often employed to extract valuable information in a timely manner as they can handle data as it is generated. The typical approach for deploying these applications explores the Cloud computing paradigm, which has limitations when data sources are geographically distributed, hence introducing high latency and achieving low processing throughput. To address these problems, current work attempts to take the computation closer to the edges of the Internet, exploring Fog computing. The effective adoption of this approach is achieved with proper throughput modeling that accounts for characteristics of the DSP application and Fog infrastructure, including the location of devices, processing and bandwidth requirements of the application, as well as selectivity and parallelism level of operators. In this work, we propose a throughput model for DSP applications embracing these characteristics. Results show that the model estimates the application throughput with less than 1% error.
Title: Online scheduling in magnetic tapes
Speaker: Carlos Cardonha (IBM Research Brazil)
Location: LIP, meeting room M7 3rd floor
Abstract: Magnetic tapes have been playing a key role as means for storage of digital data for decades, and their unsurpassed cost-effectiveness still makes them the technology of choice in several industries, such as media and entertainment. Tapes are mostly used for cold storage nowadays, and therefore the study of scheduling algorithms for read requests tailored for these devices has been largely neglected in the literature. In this article, we investigate the Linear Tape Scheduling Problem (LTSP), in which read requests associated with files stored on a single-tracked magnetic tape should be scheduled in a way that the sum of all response times are minimized. LTSP has many similarities with classical combinatorial optimization problems such as the Traveling Repairmen Problem and the Dial-a-Ride Problem restricted to the real line; nevertheless, significant differences on structural properties and strict time-limit constraints of real-world scenarios make LTSP challenging and interesting on its own. In this work, we investigate several properties and algorithms for LTSP and some of its extensions. The results allowed for the identification of 3-approximation algorithms for LTSP and efficient exact algorithms for some of its special cases. We also show that LTSPR, the version of the problem with heterogeneous release times for requests, is NP-complete. OLTSP, the online extension of LTSPR, does not admit c-competitive algorithms for any constant factor c, but we nevertheless introduce an algorithm for the problem and show through extensive computational experiments on synthetic and real-world datasets that different embodiments of the proposed strategy are computationally efficient and over-perform by orders of magnitude an algorithm being currently used by real-world tape file systems.
Mini-bio: Carlos Cardonha is a Research Staff Member at the Natural Resources Optimization group at IBM Research Brazil, with a Ph.D. in Mathematics (T.U. Berlin) and with a Bachelor’s and a Master’s degree in Computer Science (Universidade de São Paulo). His primary research interests are mathematical programming and theoretical computer science, with focus on the application of techniques in mixed integer linear programming, combinatorial optimization, and algorithms design and analysis to real-world and/or operations research problems.
Title: SeeDep: Deploying Reproducible Application Topologies on Cloud Platform
Speaker: Cyril Seguin (LIP, AVALON team)
Location: LIP, Salle du conseil du LIP 3rd floor
As part of the scientific method, any researcher should be able to reproduce the experimentation in order to not only verify the result but also evaluate and compare this experimentation with other approaches. The need of a standard tool allowing researchers to easily generate, share and reproduce experiments set-up arises. In this talk, I’ll present SeeDep, a framework aiming at being such a standard tool. By associating a generation key to a network experiment set-up, SeeDep allows for reproducing network experiments independently from the used infrastructure.
Title: Improving power-efficiency through fine-grain monitoring in HPC clusters
Speaker: Mathieu Stoffel (LIG, CORSE team)
Location: LIP, meeting room M7 3rd floor
Nowadays, power and energy consumption are of paramount importance. Further, reaching the Exascale target will not be possible in the short term without major breakthroughs in software and hardware technologies to meet power consumption constraints.
In this context, this papers discusses the design and implementation of a system-wide tool to monitor, analyze and control power/energy consumption in HPC clusters.
We developed a lightweight tool that relies on a fine-grain sampling of two CPU performance metrics: instructions throughput (IPC) and last level cache bandwidth.
Thanks to the information provided by these metrics about hardware resources’ activity, and using DVFS to control power/performance, we show that it is possible to achieve up to 16% energy savings at the cost of less than 3% performance degradation on real HPC applications.
Title: Deployment of services in Fog Computing
Speaker: Farah Ait Salaht
Fog Computing, complementary to Cloud Computing, has recently emerged as a new paradigm that extends the computing infrastructure from the center to the edge of the network. Motivated by a rapidly increasing number of devices and Internet of Things (IoT) applications at the extreme edge of the network that implies the need for timely and local processing, Fog Computing offers a promising solution to move computational capabilities closer to the end-devices. Deploying applications to Fog nodes in a QoS- and context-aware manner is a challenging task due to the heterogeneity and scale of Fog infrastructures. This talk discusses what Fog is, provides an up-to-date review of service placement problem in such an environment (problem statement, problem formulation, optimization metrics, and optimization strategies), depict the variants of the problem and the current proposals coming from the research community.