Non quia difficilia sunt non audemus, sed quia non audemus difficilia sunt
Home -> Publications
all years
    edited volumes
  Full CV [pdf]


  Past Events

Publications of Torsten Hoefler
Copyright Notice:

The documents distributed by this server have been provided by the contributing authors as a means to ensure timely dissemination of scholarly and technical work on a noncommercial basis. Copyright and all rights therein are maintained by the authors or by other copyright holders, notwithstanding that they have offered their works here electronically. It is understood that all persons copying this information will adhere to the terms and constraints invoked by each author's copyright. These works may not be reposted without the explicit permission of the copyright holder.

B. Prisacari, G. Rodriguez, C. Minkenberg and T. Hoefler:

 Bandwidth-optimal All-to-all Exchanges in Fat Tree Networks

(In Proceedings of the 27th International ACM Conference on International Conference on Supercomputing, presented in Eugene, OR, USA, pages 139--148, ACM, ISBN: 978-1-4503-2130-3, Jun. 2013)


The personalized all-to-all collective exchange is one of the most challenging communication patterns in HPC applications in terms of performance and scalability. In the context of the fat trees family of interconnection networks, widely used in current HPC systems and datacenters, we show that there is potential for optimizing this traffic pattern by deriving a tight theoretical lower bound for the bandwidth needed in the network to support such communication in a non-contending way. Current state of the art methods require up to twice as much bisection bandwidth as this theoretical minimum. We propose a set of optimized exchanges that use exactly the minimum amount of resources and exhibit close to ideal performance. This enables cost-effective networks, i.e., with as little as half the bisection bandwidth required by current state of the art methods, to exhibit quasi optimal performance under all-to-all traffic. In addition to supporting our claims by mathematical proofs, we include simulation results that confirm their correctness in practical system configurations.


download article:


  author={B. Prisacari and G. Rodriguez and C. Minkenberg and T. Hoefler},
  title={{Bandwidth-optimal All-to-all Exchanges in Fat Tree Networks}},
  booktitle={Proceedings of the 27th International ACM Conference on International Conference on Supercomputing},
  location={Eugene, OR, USA},

serving:© Torsten Hoefler