Scalable compression and replay of communication traces in massively parallel environments

Characterizing the communication behavior of largescale applications is a difficult and costly task due to code and system complexity as well as their long execution times. An alternative to running actual codes is to gather their communication traces and then replay them, which facilitates application tuning and future procurements. While past approaches lacked lossless scalable trace collection, we contribute an approach that provides near constant-size communication traces regardless of the number of nodes while preserving structural information. We introduce intra- and inter-node compression techniques of MPI events and present results of our implementation for BlueGene/L. Given this novel capability, we discuss its impact on communication tuning and beyond. To the best of our knowledge, near constant-size representation of MPI traces in a scalable manner combined with deterministic MPI call replay are without any precedence