  This short report describes the scaling, up to 1024 software processes and
hardware cores, of a distributed simulator of plastic spiking neural networks.
A previous report demonstrated good scalability of the simulator up to 128
processes. Herein we extend the speed-up measurements and strong and weak
scaling analysis of the simulator to the range between 1 and 1024 software
processes and hardware cores. We simulated two-dimensional grids of cortical
columns including up to ~20G synapses connecting ~11M neurons. The neural
network was distributed over a set of MPI processes and the simulations were
run on a server platform composed of up to 64 dual-socket nodes, each socket
equipped with Intel Haswell E5-2630 v3 processors (8 cores @ 2.4 GHz clock).
All nodes are interconned through an InfiniBand network. The DPSNN simulator
has been developed by INFN in the framework of EURETILE and CORTICONIC European
FET Project and will be used by the WaveScalEW tem in the framework of the
Human Brain Project (HBP), SubProject 2 - Cognitive and Systems Neuroscience.
This report lays the groundwork for a more thorough comparison with the neural
simulation tool NEST.
