Large Scale Peer to Peer Performance Evaluations, with Gauss-Jordan Method as an Example Serge G. Petiton, and Lamine Aouad Laboratoire d'Informatique Fondamentale de Lille Universite des Sciences et Technologies de Lille Cite Scientifique, M3 59655 Villeneuve d'Ascq, FRANCE {petiton,aouad}@lifl.fr Abstract. This paper presents a large scale block-based Gauss-Jordan algorithm to invert very large dense matrices. This inversion proposes to exploit a peer-to-peer platform. We assume that we access to a acheduler that propose strategies allowing "owner computes" and data migration anticipation heuristics. We present performance theoretical evaluation results showing that an efficiency of 30% is possible to invert a very large matrix on a platform where peers are heterogeneous and interconnected by a 64 Mbits's network and with a sufficient number of computers. If we use a fast internet, this simulation shows that efficiency drop to 5%. Nevertheless, we discuss that, in this case, the classical evaluation model is not well-adopted to this peer to peer computing paradigm for large scale sientific computing with heterogeneous computers.