  We present our recent code modernizations of the of the ab initio molecular
dynamics program CPMD (www.cpmd.org) with a special focus on the ultra-soft
pseudopotential (USPP) code path. Following the internal instrumentation of
CPMD, all time critical routines have been revised to maximize the
computational throughput and to minimize the communication overhead for optimal
performance. Throughout the program missing hybrid MPI+OpenMP parallelization
has been added to optimize scaling. For communication intensive routines, as
the multiple distributed 3d FFTs of the electronic states and distributed
matrix-matrix multiplications related to the $\beta$-projectors of the
pseudopotentials, this MPI+OpenMP parallelization now overlaps computation and
communication. The necessary partitioning of the workload is optimized by an
auto-tuning algorithm. In addition, the largest global MPI_Allreduce operation
has been replaced by highly tuned node-local parallelized operations using MPI
shared-memory windows to avoid inter-node communication. A batched algorithm
for the multiple 3d FFTs improves the throughput of the MPI_Alltoall
communication and, thus, the scalability of the implementation, both for USPP
and for the frequently used norm-conserving pseudopotential code path. The
enhanced performance and scalability is demonstrated on a mid-sized benchmark
system of 256 water molecules and further water systems of from 32 up to 2048
molecules.
