About me

Welcome to my home page! My name is Vasileios (Vasilis) Karakostas.

I am an Assistant Professor at the Department of Informatics and Telecommunications of the National and Kapodistrian University of Athens. I am member of the Computer Architecture Lab. My research interests lie in the areas of computer architecture, memory systems, hardware/OS interaction, operating systems, resource management, and parallel systems.

Before joining the University of Athens, I was a postdoctoral researcher at the Computing Systems Lab of the School of Electrical and Computer Engineering of the National Technical University of Athens.

I received my PhD degree in Computer Architecture from Universitat Politecnica de Catalunya and Barcelona Supercomputing Center.

If you are interested in doing research on topics related to computer architecture, HW/OS interaction, and systems, feel free to reach out!


I am working on topics related to memory systems, and particularly on virtual memory, memory management, cache management, and recently on non-volatile memories. I am also working on topics related to resource management and resource efficiency in data centers, and I am particularly interested in exploring challenges related to serverless computing. My PhD thesis focused on analyzing and improving the performance and energy-efficiency of virtual memory.

Supervision and Mentorship

I have the honor to co-supervise the PhD thesis of Chloe Alverti at NTUA, together with Prof. Georgios Goumas.

EU Projects

I am currently working on the Vitamin-V, Neuropuls, and REBECCA Horizon Europe research projects.

During my postdoctoral research at CSLab, I worked on the DAPHNE EU H2020 research project (Dec 2020 - Nov 2022) and the ACTiCLOUD EU H2020 research project (Jan 2017 - Dec 2019).



Impact of Voltage Scaling on Soft Errors Susceptibility of Multicore Server CPUs
Dimitris Agiakatsikas, George Papadimitriou, Vasileios Karakostas, Dimitris Gizopoulos, Mihalis Psarakis, Camille Belanger-Champagne, and Ewart Blackmore
56th IEEE/ACM International Symposium on Microarchitecture (MICRO 2023)

Vitamin-V: Virtual Environment and Tool-boxing for Trustworthy Development of RISC-V based Cloud Services
Ramon Canal, Cristiano Chenet, Angelos Arelakis, José Maria Arnau, Josep Ll. Berral, Aaron Call, Stefano Di Carlo, Juan José Costa, Dimitris Gizopoulos, Vasileios Karakostas, Francesco Lubrano, Konstantinos Nikas, Yiannis Nikolakopoulos, Beatriz Otero, George Papadimitriou, Ioannis Papaefstathiou, Dionisios Pnevmatikatos, Daniel Raho, Alvise Rigo, Eva Rodríguez, Alessandro Savino, Alberto Scionti, Nikolaos Tampouratzis, and Alex Torregrosa
26th Euromicro Conference Series on Digital System Design (DSD 2023) & Poster in RISC-V Summit Europe 2023
[PDF] [Extended abstract]

Enabling Design Space Exploration of RISC-V Accelerator-rich Computing Systems on gem5
Odysseas Chatzopoulos, George Papadimitriou, Vasileios Karakostas, and Dimitris Gizopoulos
Poster in RISC-V Summit Europe 2023

Validation, Verification, and Testing (VVT) of future RISC-V powered cloud infrastructures: the Vitamin-V Horizon Europe Project perspective
Marti Alonso, David Andreu, Ramon Canal, Stefano Di Carlo, Cristiano Pegoraro Chenet, Juanjo Costa, Andreu Girones, Dimitris Gizopoulos, Vasileios Karakostas, Beatriz Otero, George Papadimitriou, Eva Rodríguez, and Alessandro Savino
28th IEEE European Test Symposium (ETS 2023)

NEUROPULS: NEUROmorphic energy-efficient secure accelerators based on Phase change materials aUgmented siLicon photonicS
Fabio Pavanello, Cédric Marchand, Ian O'Connor, Régis Orobtchouk, Fabien Mandorlo, Xavier Letartre, Sébastien Cueff, Elena Ioana Vatajelu, Giorgio Di Natale, Benoit Cluzel, Aurelien Coillet, Benoît Charbonnier, Pierre Noe, Frantisek Kavan, Martin Zoldak, Michal Szaj, Peter Bienstman, Thomas Van Vaerenbergh, Ulrich Rührmair, Paulo F. Flores, Luís Guerra e Silva, Ricardo Chaves, Luís Miguel Silveira, Mariano Ceccato, Dimitris Gizopoulos, George Papadimitriou, Vasileios Karakostas, Axel Brando, Francisco J. Cazorla, Ramon Canal, Pau Closas, Adria Gusi-Amigo, Paolo Crovetti, Alessio Carpegna, Tzamn Melendez Carmona, Stefano Di Carlo, and Alessandro Savino
28th IEEE European Test Symposium (ETS 2023)

FaaSCell: A Case for Intra-node Resource Management: Work-In-Progress
Christos Katsakioris, Chloe Alverti, Konstantinos Nikas, Stratos Psomadakis, Vasileios Karakostas, and Nectarios Koziris
1st Workshop on SErverless Systems, Applications and MEthodologies (SESAME 2023) - held in conjunction with EuroSys 2023


DaxVM: Stressing the Limits of Memory as a File Interface
Chloe Alverti, Vasileios Karakostas, Nikhita Kunati, Georgios Goumas, and Michael Swift
55th IEEE/ACM International Symposium on Microarchitecture (MICRO 2022)
[PDF] [slides] [code]

FaaS in the Age of (sub-)μs I/O: A Performance Analysis of Snapshotting
Christos Katsakioris, Chloe Alverti, Vasileios Karakostas, Konstantinos Nikas, Georgios Goumas, and Nectarios Koziris
15th ACM International System and Storage Conference (SYSTOR 2022)
[PDF] [slides] [video] [code]

DAPHNE: An Open and Extensible System Infrastructure for Integrated Data Analysis Pipelines
Patrick Damme, Marius Birkenbach, Constantinos Bitsakos, Matthias Boehm, Philippe Bonnet, Florina Ciorba, Mark Dokter, Pawel Dowgiallo, Ahmed Eleliemy, Christian Faerber, Georgios Goumas, Dirk Habich, Niclas Hedam, Marlies Hofer, Wenjun Huang, Kevin Innerebner, Vasileios Karakostas, Roman Kern, Tomaž Kosar, Alexander Krause, Daniel Krems, Andreas Laber, Wolfgang Lehner, Eric Mier, Marcus Paradies, Bernhard Peischl, Gabrielle Poerwawinata, Stratos Psomadakis, Tilmann Rabl, Piotr Ratuszniak, Pedro Silva, Nikolai Skuppin, Andreas Starzacher, Benjamin Steinwender, Ilin Tolovski, Pınar Tözün, Wojciech Ulatowski, Yuanyuan Wang, Izajasz Wrosz, Aleš Zamuda, Ce Zhang, and Xiao Xiang Zhu
12th Annual Conference on Innovative Data Systems Research (CIDR 2022)
[PDF] [slides] [video] [code]


Exploiting Page Table Locality for Agile TLB Prefetching
Georgios Vavouliotis, Lluc Alvarez, Vasileios Karakostas, Konstantinos Nikas, Nectarios Koziris, Daniel A. Jimenez, and Marc Casas
48th International Symposium on Computer Architecture (ISCA 2021)
[PDF] [slides (pdf)] [lightning talk] [poster] [video]

SynCron: Efficient Synchronization Support for Near-Data-Processing Architectures
Christina Giannoula, Nandita Vijaykumar, Nikela Papadopoulou, Vasileios Karakostas, Ivan Fernandez, Juan Gómez Luna, Lois Orosa, Nectarios Koziris, Georgios Goumas, and Onur Mutlu
27th IEEE International Symposium on High-Performance Computer Architecture (HPCA 2021)
[PDF] [slides] [lightning talk] [video]


A Configurable TLB Hierarchy for the RISC-V Architecture
Nikolaos Charalampos Papadopoulos, Vasileios Karakostas, Konstantinos Nikas, Nectarios Koziris, and Dionisios N. Pnevmatikatos
30th International Conference on Field-Programmable Logic and Applications (FPL 2020)
[PDF] [slides] [video] [code]

Enhancing and Exploiting Contiguity for Fast Memory Virtualization
Chloe Alverti, Stratos Psomadakis, Vasileios Karakostas, Jayneel Gandhi, Konstantinos Nikas, Georgios Goumas, and Nectarios Koziris
47th International Symposium on Computer Architecture (ISCA 2020)
[PDF] [slides] [lightning talk] [video] [code]

Enabling Virtual Memory Research on RISC-V with a Configurable TLB Hierarchy for the Rocket Chip Generator
Nikolaos Charalampos Papadopoulos, Vasileios Karakostas, Konstantinos Nikas, Nectarios Koziris, and Dionisios N. Pnevmatikatos
Fourth Workshop on Computer Architecture Research with RISC-V (CARRV 2020)
[PDF] [slides] [video] [code]


ACTiManager: An end-to-end interference-aware cloud resource manager
Stratos Psomadakis, Stefanos Gerangelos, Dimitrios Siakavaras, Ioannis Papadakis, Marina Vemmou, Aspa Skalidi, Vasileios Karakostas, Konstantinos Nikas, Nectarios Koziris, and Georgios Goumas.
Demo & Poster in 20th International Middleware Conference (Middleware 2019)
[PDF] [poster] [demo] [code]

DICER: Diligent Cache Partitioning for Efficient Workload Consolidation
Konstantinos Nikas, Nikela Papadopoulou, Dimitra Giantsidi, Vasileios Karakostas, Georgios Goumas, and Nectarios Koziris.
48th International Conference on Parallel Processing (ICPP 2019)
[PDF] [slides]


Performance Prediction of NUMA Placement: A Machine-Learning Approach
Fanourios Arapidis, Vasileios Karakostas, Nikela Papadopoulou, Konstantinos Nikas, Georgios Goumas, and Nectarios Koziris.
1st International Workshop on Next Generation Clouds for Extreme Data (XtremeCLOUD 2018) - held in conjunction with CloudCom 2018
[PDF] [slides]

Efficient Resource Management for Data Centers: The ACTiCLOUD approach
Vasileios Karakostas, Georgios Goumas, Ewnetu Bayuh Lakew, Erik Elmroth, Stefanos Gerangelos, Simon Kolberg, Konstantinos Nikas, Stratos Psomadakis, Dimitrios Siakavaras, Petter Svard, and Nectarios Koziris.
18th International Conference on Embedded Computer Systems: Architectures, Modeling, and Simulation (SAMOS 2018)

PPTA: Prefetch-Process-Thread-Alternation to Speed Up Dijkstra's Algorithm
Konstantinos Kanellopoulos, Konstantinos Nikas, Dimitrios Siakavaras, Vasileios Karakostas, Georgios Goumas, Nectarios Koziris
11th Workshop on Programmability and Architectures for Heterogeneous Multicores (MULTIPROG 2018) - held in conjunction with HiPEAC 2018


ACTiCLOUD: Enabling the Next Generation of Cloud Applications
Georgios Goumas, Konstantinos Nikas, Ewnetu Bayuh Lakew, Christos Kotselidis, Andrew Attwood, Erik Elmroth, Michail Flouris, Nikos Foutris, John Goodacre, Davide Grohmann, Vasileios Karakostas, Panagiotis Koutsourakis, Martin Kersten, Mikel Lujàn, Einar Rustad, John Thomson, Luis Tomás, Atle Vesterkjaer, Jim Webber, Ying Zhang, and Nectarios Koziris
37th IEEE International Conference on Distributed Computing Systems (ICDCS 2017)

Improving QoS and Utilisation in modern multi-core servers with Dynamic Cache Partitioning
Ioannis Papadakis, Konstantinos Nikas, Vasileios Karakostas, Georgios Goumas, and Nectarios Koziris
2nd Workshop on Co-Scheduling of HPC Applications (COSH 2017) - held in conjunction with HiPEAC 2017


Range Translations for Fast Virtual Memory
Jayneel Gandhi*, Vasileios Karakostas*, Furkan Ayar, Adrián Cristal, Mark D. Hill, Kathryn S. McKinley, Mario Nemirovsky, Michael M. Swift, and Osman Unsal
IEEE Micro Special Issue: Micro's Top Picks from 2015 Computer Architecture Conferences (Volume 36, Issue 3, May-June 2016)
(*: joint first authors)

Energy-Efficient Address Translation
Vasileios Karakostas, Jayneel Gandhi, Adrián Cristal, Mark D. Hill, Kathryn S. McKinley, Mario Nemirovsky, Michael M. Swift, and Osman Unsal
22nd IEEE International Symposium on High Performance Computer Architecture (HPCA 2016)


NEMsCAM: A Novel CAM Cell based on Nano-Electro-Mechanical Switch and CMOS for Energy Efficient TLBs
Azam Seyedi, Vasileios Karakostas, Stefan Cosemans, Adrián Cristal, Mario Nemirovsky, and Osman Unsal
IEEE/ACM International Symposium on Nanoscale Architectures (NANOARCH 2015)

Redundant Memory Mappings for Fast Access to Large Memories
Vasileios Karakostas*, Jayneel Gandhi*, Furkan Ayar, Adrián Cristal, Mark D. Hill, Kathryn S. McKinley, Mario Nemirovsky, Michael M. Swift, and Osman Unsal
42nd International Symposium on Computer Architecture (ISCA 2015)
Selected for IEEE Micro's Top Picks as one of the best computer architecture papers of 2015
(*: joint first authors)


Performance Analysis of the Memory Management Unit under Scale-out Workloads
Vasileios Karakostas, Osman Unsal, Mario Nemirovsky, Adrián Cristal, and Michael Swift
IEEE International Symposium on Workload Characterization (IISWC 2014)

Dynamic Transaction Coalescing
Srdan Stipic, Vasileios Karakostas, Vesna Nowack, Adrián Cristal, Osman Unsal, and Mateo Valero
11th conference on ACM Computing Frontiers (CF 2014)


Improving the Energy Efficiency of Hardware-Assisted Watchpoint Systems
Vasileios Karakostas, Saša Tomić, Osman Unsal, Mario Nemirovsky, and Adrián Cristal
50th Design Automation Conference (DAC 2013)


DiDi: Mitigating The Performance Impact of TLB Shootdowns Using A Shared TLB Directory
Carlos Villavieja, Vasileios Karakostas, Lluis Vilanova, Yoav Etsion, Alex Ramirez, Avi Mendelson, Nacho Navarro, Adrián Cristal, and Osman Unsal
20th International Conference on Parallel Architectures and Compilation Techniques (PACT 2011)

RMS-TM: A Comprehensive Benchmark Suite for Transactional Memory Systems
Gokcen Kestor, Vasileios Karakostas, Osman Unsal, Adrián Cristal, Ibrahim Hur, and Mateo Valero
2nd ACM/SPEC International Conference on Performance Engineering (ICPE 2011).
Best Paper Award


Improving the Performance and Energy-efficiency of Virtual Memory
PhD Thesis, Universitat Politecnica de Catalunya, UPC, April 2016


Parallel Systems (undergraduate) (Fall 2022, 2023)

Logic Design (undergraduate) (Fall 2023)

Large-scale Computing Systems (undergraduate) (Spring 2023)

Parallel Computing Systems (graduate) (Spring 2023)


Ph.D. in Computer Architecture, 2016
  Universitat Politecnica de Catalunya (UPC)

M.S. in Computer Architecture, Networks, and Systems, 2012
  Universitat Politecnica de Catalunya (UPC)

Diploma in Electrical and Computer Engineering, 2009
  National Technical University of Athens (NTUA)


National and Kapodistrian University of Athens
Department of Informatics and Telecommunications
Panepistimiopolis, Ilissia, GR 15784, Athens, Greece (Office A43, 1st floor)

e-mail: vkarakos _at_ di.uoa.gr
URL: http://di.uoa.gr/~vkarakos/
Tel: +30-210-7275208

Last modified: 15th September 2023