Fotis Nikolaidis

Dr. Fotis Nikolaidis

orcid

Research Focus & Metrics

Academic Career Length

5Years (2022-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

View All Publications
31 July 2023 in Future Internet
Verified
Journal Article
Open access
PDF file
FNFotis Nikolaidis
Fotis Nikolaidis
MSMoysis Symeonides
Moysis Symeonides
Demetris TrihinasDemetris Trihinas
Demetris Trihinas
Federated learning (FL) is a transformative approach to Machine Learning that enables the training of a shared model without transferring private data to a central location. This decentralized training paradigm has found particular applicability in edge computing, where IoT devices and edge nodes often possess limited computational power, network bandwidth, and energy resources. While various techniques have been developed to optimize the FL training process, an important question remains unanswered: how should resources be allocated in the training workflow? To address this question, it is crucial to understand the nature of these resources. In physical environments, the allocation is typically performed at the node level, with the entire node dedicated to executing a single workload. In contrast, virtualized environments allow for the dynamic partitioning of a node into containerized units that can adapt to changing workloads. Consequently, the new question that arises is: how can a physical node be partitioned into virtual resources to maximize the efficiency of the FL process? To answer this, we investigate various resource allocation methods that consider factors such as computational and network capabilities, the complexity of datasets, as well as the specific characteristics of the FL workflow and ML backend. We explore two scenarios: (i) running FL over a finite number of testbed nodes and (ii) hosting multiple parallel FL workflows on the same set of testbed nodes. Our findings reveal that the default configurations of state-of-the-art cloud orchestrators are sub-optimal when orchestrating FL workflows. Additionally, we demonstrate that different libraries and ML models exhibit diverse computational footprints. Building upon these insights, we discuss methods to mitigate computational interferences and enhance the overall performance of the FL pipeline execution.

25 August 2023
Verified
Book Chapter
Closed access
PDF file
ACAntony Chazapis
Antony Chazapis
FNFotis Nikolaidis
Fotis Nikolaidis
MMManolis Marazakis
Manolis Marazakis
ABAngelos Bilas
Angelos Bilas

4 December 2023
Verified
Conference Paper
Open access
MSMoysis Symeonides
Moysis Symeonides
FNFotis Nikolaidis
Fotis Nikolaidis
Demetris TrihinasDemetris Trihinas
Demetris Trihinas
GPGeorge Pallis
George Pallis
MDMarios D. Dikaiakos
Marios D. Dikaiakos
ABAngelos Bilas
Angelos Bilas
Federated Learning has become the de facto paradigm for training AI models under a distributed modality where the computational effort is spread across several clients without sharing local data. Despite its distributed nature, enabling FL in an Edge-Cloud continuum is challenging with resource and network heterogeneity, different AI models and libraries, and non-uniform data distributions, all hampering QoS and limiting innovation potential. This work introduces FedBed, a testing framework that enables the rapid and reproducible benchmarking of FL deployments on virtualized testbeds. FedBed aids users in assessing the numerous trade-offs that result from combining a variety of FL software and infrastructure configurations in Edge-Cloud settings. This reduces the time-consuming process that includes the setup of either a virtual physical or emulation testbed, experiment configurations, and the monitoring of the resulting FL testbed.

11 April 2024 in IoT
Verified
Journal Article
Open access
PDF file
MSMoysis Symeonides
Moysis Symeonides
Demetris TrihinasDemetris Trihinas
Demetris Trihinas
FNFotis Nikolaidis
Fotis Nikolaidis
Federated learning (FL) is rapidly shaping into a key enabler for large-scale Artificial Intelligence (AI) where models are trained in a distributed fashion by several clients without sharing local and possibly sensitive data. For edge computing, sharing the computational load across multiple clients is ideal, especially when the underlying IoT and edge nodes encompass limited resource capacity. Despite its wide applicability, monitoring FL deployments comes with significant challenges. AI practitioners are required to invest a vast amount of time (and labor) in manually configuring state-of-the-art monitoring tools. This entails addressing the unique characteristics of the FL training process, including the extraction of FL-specific and system-level metrics, aligning metrics to training rounds, pinpointing performance inefficiencies, and comparing current to previous deployments. This work introduces FedMon, a toolkit designed to ease the burden of monitoring FL deployments by seamlessly integrating the probing interface with the FL deployment, automating the metric extraction, providing a rich set of system, dataset, model, and experiment-level metrics, and providing the analytic means to assess trade-offs and compare different model and training configurations.

25 September 2024 in arXiv
Verified
Preprint
Open access
PDF file
ACAntony Chazapis
Antony Chazapis
EMEvangelos Maliaroudakis
Evangelos Maliaroudakis
FNFotis Nikolaidis
Fotis Nikolaidis
MMManolis Marazakis
Manolis Marazakis
ABAngelos Bilas
Angelos Bilas
The escalating complexity of applications and services encourages a shift towards higher-level data processing pipelines that integrate both Cloud-native and HPC steps into the same workflow. Cloud providers and HPC centers typically provide both execution platforms on separate resources. In this paper we explore a more practical design that enables running unmodified Cloud-native workloads directly on the main HPC cluster, avoiding resource partitioning and retaining the HPC center's existing job management and accounting policies.

25 August 2023
Verified
Book Chapter
Closed access
PDF file
FNFotis Nikolaidis
Fotis Nikolaidis
ACAntony Chazapis
Antony Chazapis
MMManolis Marazakis
Manolis Marazakis
ABAngelos Bilas
Angelos Bilas