Vasileios Karakostas

Postdoctoral Researcher

Computing Systems Laboratory - CSLab
School of Electrical and Computer Engineering
National Technical University of Athens, Greece

e-mail: vkarakos _at_

About me

Welcome to my home page!

My name is Vasileios (Vasilis) Karakostas. I am a Postdoctoral Researcher at the Computing Systems Laboratory (CSLab) of the School of Electrical and Computer Engineering (ECE) of the National Technical University of Athens (NTUA), working together with Prof. Nectarios Koziris, Prof. Georgios Goumas, and Dr. Konstantinos Nikas. Among other things, I am currently working on the ACTiCLOUD EU research project, that seeks to improve resource efficiency and utilization in data centers.

I received my PhD degree in Computer Architecture from Universitat Politecnica de Catalunya (DAC, UPC) and Barcelona Supercomputing Center (BSC), under the supervision of Mario Nemirovsky, Osman S. Unsal, and Adrian Cristal. My PhD thesis focused on analyzing and improving the performance and energy-efficiency of virtual memory.

My research interests lie in the areas of computer architecture, memory systems, hardware/OS interaction, and parallel systems.


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)



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

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

Teaching Assistance

Advanced Computer Architecture [Spring 2018, Spring 2017]

Operating Systems Laboratory [Autumn 2018, Spring 2018, Spring 2017]


National Technical University of Athens (NTUA)
Computing Systems Laboratory, Room 21.34B
School of Electrical and Computer Engineering
Department of Computer Science
9 Heroon Polytechneiou, Polytexneioypolis (Zografou Campus),
Zografou, 15780, Athens, Greece

e-mail: vkarakos _at_
Tel: +30-210-7724133, Fax: +30-210-7721292

Last modified: 1st February 2019