Bartosz Bogdański successfully defended his PhD

On 12th August 2014 Bartosz Bogdański successfully defended his PhD thesis Optimized Routing for Fat-Tree Topologies. The defense took place at at 13:15 in Storstua at Simula Research Laboratory.

It is not only the number and the frequency of the processors that makes today’s supercomputers so immensely powerful. One of the most important aspects of every high-performance system is the interconnect - the network that connects the whole system together.

With the advent of cloud computing and big data, today’s high-performance systems are facing new complex multi-layered challenges. This thesis focuses on routing and proposes multiple improvements in this area. 

Thanks to the work presented in this thesis, the management of enterprise-class high-performance systems became simpler, fault-tolerance became integrated into the routing algorithms and the performance gains exceeded the expectations.

The contributions to this thesis are a set of five extended routing algorithms that build upon the original fat-tree routing presented by Eitan Zahavi. Furthermore, for the first time two advanced inter-subnet routing algorithms were presented and evaluated. The usability of these solutions is best illustrated by the fact that 3 of the presented algorithms have already found a way into all InfiniBand systems manufactured by Oracle Corporation. 

This thesis has resulted in 5 conference papers, one journal paper and 7 patents. Future work has been already undertaken and will result in additional papers and patents.

The thesis is written within the field of interconnection networks. The work has been conducted at Simula Research Laboratory and Oracle Corporation in Oslo.


Prior to the defense, at 11:15, Bartosz Bogdański presented his trial lecture Energy aspects of communication - where did the Joules go?


The adjudication committee

  • Associate Professor Maria Engracia Gomez Requena, Universitat Politècnica de València, Spain
  • Associate Professor Holger Fröning, Universität Heidelberg, Germany
  • Professor Michael Welzl, Institutt for informatikk, Universitetet i Oslo, Norway


Chair of the disputation

  • Professor Fritz Albregtsen, Institutt for informatikk, Universitetet i Oslo, Norway



  • Dr. Sven-Arne Reinemo
  • Professor Tor Skeie
  • Professor Olav Lysne


Read more: 

Announcement of the PhD defense at the University of Oslo's web pages (in Norwegian).