Section: New Results

I/O-Affinity-aware MPI Communications

Participants : Brice Goglin, Stéphanie Moreaud.

• We demonstrated in the past that the locality of I/O devices within modern computing nodes has the significant impact of the MPI communication performance [11] (Non-Uniform I/O Access, NUIOA).

• A first way to deal with such affinities would be to privilege I/O-intensive processes by placing them near the network interfaces. However, determining the communication-intensiveness may be tricky. Also, some applications have uniform communication patterns. The other way to deal with I/O affinities is to modify the implementation of communication operations given a predetermined task placement.

• We demonstrated that the implementation of collective operations should take I/O affinities into account. Deciding which steps and leaders should be involved in the algorithms based on NUIOA effects led us to improve broadcast performance significantly [34] , [18] .