VLDB 2026 Research / reviewers in the wild / expert
Christos Kozanitis
dblp:98/874
· DBLP profile ↗
16ranked-venue papers
4as first author
7since 2021 · last 2026
0000-0003-3566-1610ORCID · corroborated
Domains — the database's venue-derived domains; a paper can count in several
Systems, architecture and hardware · 10 · 6 since 2021Software engineering, systems software and programming languages · 4 · 4 since 2021Applied, interdisciplinary, general and emerging computing · 3 · 3 first-authorComputer networks · 1 · 1 first-authorGraphics, computer vision, multimedia, augmented reality and games · 1
| Year | Publication | Venue | Position |
|---|---|---|---|
| 2026 | Multi-Partner Project: dAIEDGE - A Network of Excellence for Distributed, Trustworthy, Efficient and Scalable AI at the EdgeabstractThe dAIEDGE Network of Excellence (NoE) seeks to strengthen and support the development of a dynamic European cutting-edge Artificial intelligence (AI) ecosystem under the umbrella of the European Lighthouse for AI, and to sustain the development of advanced AI. dAIEDGE fosters the exchange of ideas, concepts, and trends on cutting-edge next generation AI, creating links between ecosystem actors to help both the European Commission (EC) and the European Union (EU) and the peripheral AI constituency identify strategies for future developments in Europe. Our main objective is to advance Europe’s innovation and technology base by developing a comprehensive policy and governance approach to AI in order for the EU to become a world leader in innovation in the data economy and its applications. Alain Pagani, Haralampos-G. D. Stratigopoulos, Aysajan Abidin, Mhd Rashed Al Koutayni, Luca Benini, Angelos Bilas, Alessandro Capotondi, Roberto Cavicchioli, Brian Clerkin, Oscar Déniz-Suárez, Margaux Divernois, Baptiste Dupertuis, Dorvan Favre, Giulio Gambardella, Ander García Gangoiti, Carlo Augusto Grazia, Dominik Günzel, Jude Haris, Klodjan K. Hidri, Maïck Huguenin-Vuillemin, Manal Jammal, Paul Kling, Christos Kozanitis, Xavier Lessage, Srikanth Mandapati, Philippe Massonet, Alfio Di Mauro, Varesh Mishra, Juan Odriozola, Javier Parra 0001, Nuria Pazos, Viviane Potocnik, Miguel de Prado, Rohit Prasad, Spyridon Raptis, Gregoire Rebstein, Ignacio Sanudo Olmedo, Mohamed Selim, Chinmay Satish Shrivastav, Noelia Vállez, Giorgos Vasiliadis, Micaela Verrucchi, Enrico Vincenzi, Damian Vizár, Devendra Vyas, Stefan Wiehle |
DATE | 24 |
| 2025 | NET4EXA: Pioneering the Future of Interconnects for Supercomputing and AIabstractNET4EXA aims to develop a next-generation high-performance interconnect for HPC and AI systems, addressing the increasing demands of large-scale infrastructures, such as those required for training Large Language Models. Building upon the proven BXI (Bull eXascale Interconnect) European technology used in TOP15 supercomputers, NET4EXA will deliver the new BXI release, BXIv3, a complete hardware and software interconnect solution, including switch and network interface components. The project will integrate a fully functional pilot system at TRL 8, ready for deployment into upcoming exascale and post-exascale systems from 2025 onward. Leveraging prior research from European initiatives like RED-SEA, the previous achievements of consortium partners and over 20 years of expertise from BULL, NET4EXA also lays the groundwork for the future generation of BXI, BXIv4, providing analysis and preliminary design. The project will use a hybrid development and co-design approach, combining commercial switch technology with custom IP and FPGA-based NICs. Performances of NET4EXA BXIv3 interconnect will be evaluated using a broad portfolio of benchmarks, scientific scalable applications, and AI workloads. Michele Martinelli, Roberto Ammendola, Andrea Biagioni, Carlotta Chiarini, Ottorino Frezza, Francesca Lo Cicero, Alessandro Lonardo, Pier Stanislao Paolucci, Elena Pastorelli, Pierpaolo Perticaroli, Luca Pontisso, Cristian Rossi, Francesco Simula, Piero Vicini, David Colin, Gregoire Pichon, Alexandre Louvet, John Gliksberg, Matteo Turisini, Andrea Monterubbiano, Jean-Philippe Nomine, Denis Dutoit, Hugo Taboada, Lilia Zaourar, Mohamed Benazouz, Angelos Bilas, Fabien Chaix, Manolis Katevenis, Nikolaos Chrysos, Evangelos Mageiropoulos, Christos Kozanitis, Thomas Moen, Steffen Persvold, Einar Rustad, Sandro Fiore, Fabrizio Granelli, Simone Pezzuto, Raffaello Potestio, Luca Tubiana, Philippe Velha, Flavio Vella, Daniele De Sensi, Salvatore Pontarelli |
DSD | 32 |
| 2024 | TeraHeap: Exploiting Flash Storage for Mitigating DRAM Pressure in Managed Big Data FrameworksabstractBig data analytics frameworks, such as Spark and Giraph, need to process and cache massive datasets that do not always fit on the managed heap. Therefore, frameworks temporarily move long-lived objects outside the heap (off-heap) on a fast storage device. However, this practice results in (1) high serialization/deserialization (S/D) cost and (2) high memory pressure when off-heap objects are moved back for processing. In this article, we propose TeraHeap , a system that eliminates S/D overhead and expensive GC scans for a large portion of objects in analytics frameworks. TeraHeap relies on three concepts: (1) It eliminates S/D by extending the managed runtime (JVM) to use a second high-capacity heap (H2) over a fast storage device. (2) It offers a simple hint-based interface, allowing analytics frameworks to leverage object knowledge to populate H2. (3) It reduces GC cost by fencing the collector from scanning H2 objects while maintaining the illusion of a single managed heap, ensuring memory safety. We implement TeraHeap in OpenJDK8 and OpenJDK17 and evaluate it with fifteen widely used applications in two real-world big data frameworks, Spark and Giraph. We find that for the same DRAM size, TeraHeap improves performance by up to 73% and 28% compared to native Spark and Giraph. Also, it can still provide better performance by consuming up to \(4.6\times\) and \(1.2\times\) less DRAM than native Spark and Giraph, respectively. TeraHeap can also be used for in-memory frameworks and applying it to the Neo4j Graph Data Science library improves its performance by up to 26%. Finally, it outperforms Panthera, a state-of-the-art garbage collector for hybrid DRAM-NVM memories, by up to 69%. Iacovos G. Kolokasis, Giannos Evdorou, Shoaib Akram 0001, Christos Kozanitis, Anastasios Papagiannis, Foivos S. Zakkak, Polyvios Pratikakis, Angelos Bilas |
ACM Trans. Program. Lang. Syst. | 4 |
| 2023 | TeraHeap: Reducing Memory Pressure in Managed Big Data FrameworksabstractBig data analytics frameworks, such as Spark and Giraph, need to process and cache massive amounts of data that do not always fit on the managed heap. Therefore, frameworks temporarily move long-lived objects outside the managed heap (off-heap) on a fast storage device. However, this practice results in (1) high serialization/deserialization (S/D) cost and (2) high memory pressure when off-heap objects are moved back to the heap for processing. Iacovos G. Kolokasis, Giannos Evdorou, Shoaib Akram 0001, Christos Kozanitis, Anastasios Papagiannis, Foivos S. Zakkak, Polyvios Pratikakis, Angelos Bilas |
ASPLOS (3) | 4 |
| 2022 | LatEst: Vertical elasticity for millisecond serverless executionabstractCurrent state-of-the-art serverless frameworks can-not execute functions within a few milliseconds for bursty work-loads. The reason for that is that typically they rely on horizontal elasticity to cope with the varying demand for resources, which induces high overhead in the event of a cold -start. Recent literature has focused on minimizing the overhead of horizontal elasticity using mechanisms such as snapshots. However, the spawning of new function instances still requires several tens of milliseconds. This paper proposes vertical elasticity to scale resources of serverless functions to cope with bursting workloads. We design LatEst, a controller for serverless frameworks that adapts the allocated resources of active function instances. U sing vertical scaling, LatEst can adjust to bursts of function invocations within a few milliseconds. LatEst implements a feed-back control loop to: (1) predict the required resources during workload changes and (2) react rapidly and accurately to such changes. Moreover, LatEst spawns new instances for functions when the resources of the underlying server are reaching their limit. We evaluate LatEst as an extension of vHive [1] and find that LatEst can improve tail latency of serverless functions up to 25x compared to vHive. Yannis Sfakianakis, Manolis Marazakis, Christos Kozanitis, Angelos Bilas |
CCGRID | 3 |
| 2022 | EVOLVE: Towards Converging Big-Data, High-Performance and Cloud-Computing WorldsabstractEVOLVE is a pan European Innovation Action that aims to fully-integrate High-Performance-Computing (HPC) hardware with state-of-the-art software technologies under a unique testbed, that enables the convergence of HPC, Cloud and Big-Data worlds and increases our ability to extract value from massive and demanding datasets. EVOLVE's advanced compute platform combines HPC-enabled capabilities, with transparent deployment in high abstraction level, and a versatile Big-Data processing stack for end-to-end workflows. Hence, domain experts have the potential to improve substantially the efficiency of existing services or introduce new models in the respective domains, e.g., automotive services, bus transportation, maritime surveillance and others. In this paper, we describe EVOLVE's testbed, and evaluate the performance of the integrated pilots from different domains. Achilleas Tzenetopoulos, Dimosthenis Masouros, Konstantina Koliogeorgi, Sotirios Xydis, Dimitrios Soudris, Antony Chazapis, Christos Kozanitis, Angelos Bilas, Christian Pinto, Huy-Nam Nguyen, Stelios Louloudakis, Georgios Gardikis, George Vamvakas, Michelle Aubrun, Christi Symeonidou, Vassilis Spitadakis, Konstantinos F. Xylogiannopoulos, Bernhard Peischl, Tahir Emre Kalayci, Alexander Stocker, Jean-Thomas Acquaviva |
DATE | 7 |
| 2021 | EVOLVE: HPC and cloud enhanced testbed for extracting value from large-scale diverse dataabstractEVOLVE is a pan-European Innovation Action building a converged infrastructure to bring together the HPC, Cloud, and Big Data worlds. EVOLVE's platform and software stack supports large-scale, data-intensive applications, driven primarily by industry requirements set by pilot and proof-of-concept use cases from diverse fields. Given the unprecedented data growth we are experiencing, EVOLVE's infrastructure is key in enabling the cost-effective processing of massive amounts of data and the adaptation of multiple high-end technologies, in an environment that fosters interoperability and enforces increased security. Antony Chazapis, Jean-Thomas Acquaviva, Angelos Bilas, Georgios Gardikis, Christos Kozanitis, Stelios Louloudakis, Huy-Nam Nguyen, Christian Pinto, Arno Scharl, Dimitrios Soudris |
CF | 5 |
| 2019 | Efficient Convolutional Neural Network Weight Compression for Space Data Classification on Multi-fpga PlatformsabstractConvolutional Neural Networks (CNNs) represent the cutting edge in signal analysis tasks like classification and regression. Realization of such architectures in hardware capable of performing high throughput computations, with minimal energy consumption, is a key enabling factor towards the proliferation of analysis immediately after acquisition. Our driving problem is a satellite-based remote sensing platform in which onboard signal processing and classification tasks must take place, given strict bandwidth and energy limitations. In this work, we exploit the implementation of a CNN on Field Programmable Gate Array (FPGA) platforms and explore different ways to minimize the impact of different hardware restrictions to performance. We compare our results against competing technologies such as Graphics Processing Units (GPU) in terms of throughput, latency and energy consumption. In actual experimental runs we demonstrate competitive latency and throughput of the FPGA platform vs. GPU technology at an order-of-magnitude energy savings, which is especially important for space-borne computing. George Pitsis, Grigorios Tsagkatakis, Christos Kozanitis, Ioannis Kalomoiris, Aggelos Ioannou, Apostolos Dollas, Manolis Katevenis, Panagiotis Tsakalides |
ICASSP | 3 |
| 2018 | QuMan: Profile-based Improvement of Cluster UtilizationabstractModern data centers consolidate workloads to increase server utilization and reduce total cost of ownership, and cope with scaling limitations. However, server resource sharing introduces performance interference across applications and, consequently, increases performance volatility, which negatively affects user experience. Thus, a challenging problem is to increase server utilization while maintaining application QoS. In this article, we present QuMan , a server resource manager that uses application isolation and profiling to increase server utilization while controlling degradation of application QoS. Previous solutions, either estimate interference across applications and then restrict colocation to “compatible” applications, or assume that application requirements are known. Instead, QuMan estimates the required resources of applications. It uses an isolation mechanism to create properly-sized resource slices for applications, and arbitrarily colocates applications. QuMan ’s mechanisms can be used with a variety of admission control policies, and we explore the potential of two such policies: (1) A policy that allows users to specify a minimum performance threshold and (2) an automated policy, which operates without user input and is based on a new combined QoS-utilization metric. We implement QuMan on top of Linux servers, and we evaluate its effectiveness using containers and real applications. Our single-node results show that QuMan balances highly effectively the tradeoff between server utilization and application performance, as it achieves 80% server utilization while the performance of each application does not drop below 80% the respective standalone performance. We also deploy QuMan on a cluster of 100 AWS instances that are managed by a modified version of the Sparrow scheduler [37] and, we observe a 48% increase in application performance on a highly utilized cluster, compared to the performance of the same cluster under the same load when it is managed by native Sparrow or Apache Mesos. Yannis Sfakianakis, Christos Kozanitis, Christoforos E. Kozyrakis, Angelos Bilas |
ACM Trans. Archit. Code Optim. | 2 |
| 2017 | VineTalk: Simplifying software access and sharing of FPGAs in datacentersabstractFPGA-based accelerators are becoming first class citizens in data centers. Adding FPGAs in data centers can lead to higher compute densities with improved energy efficiency for latency critical workloads, such as financial applications. However FPGA deployment in datacenters brings difficulties both to application developers, and cloud providers. Application writers need to deal with the interfacing of FPGAs on top of application logic/algorithms. On the other hand, cloud providers are reluctant face the risk that their hardware remains underutilized, due to the lack of a sharing mechanism for FPGAs. In this paper, we introduce VineTalk, a framework that reduces the programming effort associated with FPGA-based accelerators and FPGA virtualization. We integrate VineTalk with the Xilinx SDAccel development framework and we map it to the Kintex UltraScale FPGA. Our preliminary evaluation with a use-case of financial applications shows that VineTalk can offer effective FPGA sharing introducing less than 4% overhead to application execution time. Stelios Mavridis, Emmanouil Pavlidakis, Ioannis Stamoulias, Christos Kozanitis, Nikolaos Chrysos, Christoforos Kachris, Dimitrios Soudris, Angelos Bilas |
FPL | 4 |
| 2016 | GenAp: a distributed SQL interface for genomic dataabstractBACKGROUND: The impressively low cost and improved quality of genome sequencing provides to researchers of genetic diseases, such as cancer, a powerful tool to better understand the underlying genetic mechanisms of those diseases and treat them with effective targeted therapies. Thus, a number of projects today sequence the DNA of large patient populations each of which produces at least hundreds of terra-bytes of data. Now the challenge is to provide the produced data on demand to interested parties. RESULTS: In this paper, we show that the response to this challenge is a modified version of Spark SQL, a distributed SQL execution engine, that handles efficiently joins that use genomic intervals as keys. With this modification, Spark SQL serves such joins more than 50× faster than its existing brute force approach and 8× faster than similar distributed implementations. Thus, Spark SQL can replace existing practices to retrieve genomic data and, as we show, allow users to reduce the number of lines of software code that needs to be developed to query such data by an order of magnitude. Christos Kozanitis, David A. Patterson 0001 |
BMC Bioinform. | 1 |
| 2014 | Using Genome Query Language to uncover genetic variationabstractMOTIVATION: With high-throughput DNA sequencing costs dropping <$1000 for human genomes, data storage, retrieval and analysis are the major bottlenecks in biological studies. To address the large-data challenges, we advocate a clean separation between the evidence collection and the inference in variant calling. We define and implement a Genome Query Language (GQL) that allows for the rapid collection of evidence needed for calling variants. RESULTS: We provide a number of cases to showcase the use of GQL for complex evidence collection, such as the evidence for large structural variations. Specifically, typical GQL queries can be written in 5-10 lines of high-level code and search large datasets (100 GB) in minutes. We also demonstrate its complementarity with other variant calling tools. Popular variant calling tools can achieve one order of magnitude speed-up by using GQL to retrieve evidence. Finally, we show how GQL can be used to query and compare multiple datasets. By separating the evidence and inference for variant calling, it frees all variant detection tools from the data intensive evidence collection and focuses on statistical inference. AVAILABILITY: GQL can be downloaded from http://cseweb.ucsd.edu/~ckozanit/gql. Christos Kozanitis, Andrew Heiberg, George Varghese, Vineet Bafna |
Bioinform. | 1 |
| 2010 | Leaping Multiple Headers in a Single Bound: Wire-Speed Parsing Using the Kangaroo SystemabstractMore fundamental than IP lookups and packet classification in routers is the extraction of fields such as IP Dest and TCP Ports that determine packet forwarding. While parsing of packet fields used to be easy, new shim layers (e.g., MPLS, 802.1Q, MAC-in-MAC) of possibly variable length have greatly increased the worst-case path in the parse tree. The problem is exacerbated by the need to accommodate new packet headers and to extract other higher layer fields. Programmable routers for projects such as GENI will need such flexible parsers. In this paper, we describe the design and implementation of the Kangaroo system, a flexible packet parser that can run at 40 Gbps even for worst-case packet headers. Because conventional solutions that traverse the parse tree one protocol at a time are too slow, Kangaroo uses lookahead to parse several protocol headers in one step using a new architecture in which a CAM directs the next set of bytes to be extracted. The challenge is to keep the number of CAM entries from growing exponentially with the amount of lookahead. We deal with this challenge using a non-uniform traversal of the parse tree, and an offline dynamic programming algorithm that calculates the optimal walk. Our experiments on a NetFPGA prototype show a speedup of 2 compared to an architecture with a lookahead of 1. The architecture can be implemented as a parsing block in a standard 400 MHz ASIC at 40 Gbps using less than 1% of chip area. Christos Kozanitis, John Huber, Sushil Singh, George Varghese |
INFOCOM | 1 |
| 2010 | Compressing Genomic Sequence Fragments Using SlimGene
Christos Kozanitis, Christopher T. Saunders, Semyon Kruglyak, Vineet Bafna, George Varghese |
RECOMB | 1 |
| 2006 | FPGA based architecture for DNA sequence comparison and database searchabstractDNA sequence comparison is a computationally intensive problem, known widely since the competition for human DNA decryption. Database search for DNA sequence comparison is of great value to computational biologists. Several algorithms have been developed and implemented to solve this problem efficiently, but from a user base point of view the BLAST algorithm is the most widely used one. In this paper, we present a new architecture for the BLAST algorithm. The new architecture was fully designed, placed and routed. The post place-and-route cycle-accurate simulation, accounting for the I/O, shows a better performance than a cluster of workstations running highly optimized code over identical datasets. The new architecture and detailed performance results are presented in this paper Euripides Sotiriades, Christos Kozanitis, Apostolos Dollas |
IPDPS | 2 |
| 2006 | Some initial results on hardware BLAST acceleration with a reconfigurable architectureabstractThe BLAST algorithm is the prevalent tool that is used by molecular biologists for DNA sequence matching and database search. In this work we demonstrate that with an appropriate reconfigurable architecture, BLAST performance can be improved with a single-chip solution 5 times over a specialized and optimized computer cluster, or 37 times over a single computer. These initial results account for I/O and are very encouraging for the development of a large scale, reconfigurable BLAST engine Euripides Sotiriades, Christos Kozanitis, Apostolos Dollas |
IPDPS | 2 |