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Fog computing, which distributes computing resources to multiple locations between the Internet of Things (IoT) devices and the cloud, is attracting considerable attention from academia and industry. Yet, despite the excitement about the potential of fog computing, few comprehensive studies quantitatively characterizing the properties of fog computing architectures have been conducted. In this paper we examine the statistical properties of fog computing task completion latencies, which are important to understand to develop algorithms that match IoT nodes’ tasks with the best execution points within the fog computing substrate. Towards characterizing task completion latencies, we developed and deployed a set of benchmarks in 6 different locations, which included local nodes of different grades, conventional cloud computing services in two different regions, and Amazon Web Services (AWS) and Microsoft Azure serverless computing options. Using the developed infrastructure, we conducted a series of targeted experiments with a node invoking our benchmarks from different locations and in different conditions. The empirical study elucidated several important properties of task execution latencies, including latency variation across different execution points and execution options, and stability with respect to time. The study also demonstrated important properties of serverless execution options, and showed that statistical structure of computing latencies can be accurately characterized based on a small number (only 10–50) of latency samples. The complete measurement set we have captured as part of this study is publicly available.
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Exploiting Equivalence to Efficiently Enhance the Accuracy of Cognitive Services
Equivalent services deliver the same functionality with dissimilar non-functional characteristics, including latency, accuracy, and cost. With these dissimilarities in mind, developers can exploit the combined execution of equivalent services to increase accuracy, shorten latency, or reduce cost. However, it remains unknown how to effectively combine equivalent services to satisfy application requirements. With the recent surge in popularity of machine learning, different vendors offer a plethora of equivalent services, whose characteristics are mostly undocumented. As a result, developers cannot make an informed decision about which service to select from a set of equivalent services. To address this problem, we explore different service combination strategies (i.e., majority voting, weighted-majority voting, stacking, and custom) to ascertain their impact on nonfunctional characteristics. In particular, we study how these strategies impact the accuracy, cost, and latency of the face detection task and validate our findings on the sentiment analysis task. We consider the combined executions of commercial web services, deployed in the cloud, and open-source implementations, deployed as edge services. Our evaluation reveals that the combined execution of equivalent services is most effective for improving cost and latency. Informed by our experimental results, we formulate practical guidelines to help developers identify the best execution strategy for a given set of services.
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- Award ID(s):
- 1717065
- PAR ID:
- 10154790
- Date Published:
- Journal Name:
- 2019 IEEE International Conference on Cloud Computing Technology and Science (CloudCom)
- Page Range / eLocation ID:
- 143 to 150
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Conference Paper:
- https://doi.org/10.1109/CloudCom.2019.00031
