  This document is one of the deliverable reports created for the ESCAPE
project. ESCAPE stands for Energy-efficient Scalable Algorithms for Weather
Prediction at Exascale. The project develops world-class, extreme-scale
computing capabilities for European operational numerical weather prediction
and future climate models. This is done by identifying Weather & Climate dwarfs
which are key patterns in terms of computation and communication (in the spirit
of the Berkeley dwarfs). These dwarfs are then optimised for different hardware
architectures (single and multi-node) and alternative algorithms are explored.
Performance portability is addressed through the use of domain specific
languages.
  This deliverable provides an evaluation of the work performed within ESCAPE
to port different dwarfs to accelerators, using different programming models. A
key metric of the evaluation is the performance portability of the resulting
porting efforts. Portability means that a single source code containing the
numerical operators can be compiled and run in multiple architectures, while
performance portability additionally requires that the single source code runs
efficiently in all the different architectures.
  As results of other deliverables like D2.1, D2.4 ESCAPE provides a collection
of dwarfs ported to different computing architectures like traditional CPUs,
Intel XeonPhi and NVIDIA GPUs. Additionally D3.3 went through an optimization
process to obtain efficient and energy efficient dwarfs.
  In this deliverable we present a review of the different programming models
employed and their use to port various dwarfs of ESCAPE. A final evaluation of
the different approaches based on different metrics like performance
portability, readability of the numerical methods, efforts to port a dwarf and
efficiency of the implementation obtained is reported.
