The first summer school of the Joint-Laboratory was held at Sophia Antipolis, on the French riviera, on June 12th-13th, following the first JLESC Workshop. Both events were supported by the PUF in the context of the NEXTGN project. The theme of this summer school was on performance metrics, modeling and simulation of large HPC systems. This summer school was offered to students (mainly PhD students and post-docs) of the collaboration and open to students and faculties outside of the collaboration, if room. Up to a maximum of 30 students were considered.