  We present a detailed strong and weak scaling analysis of PICCANTE, an open
source, massively parallel, fully-relativistic Particle-In-Cell (PIC) code. PIC
codes are widely used in plasma physics and astrophysics to study the cases
where kinetic effects are relevant. PICCANTE is primarily developed to study
laser-plasma interaction. Within a PRACE Preparatory Access Project, various
revisions of different routines of the code have been analysed on the HPC
systems JUQUEEN at Juelich Supercomputing Centre (JSC), Germany, and FERMI at
CINECA, Italy, to improve scalability and I/O performance of the application.
The diagnostic tool Scalasca is used to identify suboptimal routines. Different
output strategies are discussed. The detailed strong and weak scaling behaviour
of the improved code are presented in comparison with the original version of
the code.
