  As hardware architectures are evolving in the push towards exascale,
developing Computational Science and Engineering (CSE) applications depend on
performance portable approaches for sustainable software development. This
paper describes one aspect of performance portability with respect to
developing a portable library of kernels that serve the needs of several CSE
applications and software frameworks. We describe Kokkos Kernels, a library of
kernels for sparse linear algebra, dense linear algebra and graph kernels. We
describe the design principles of such a library and demonstrate portable
performance of the library using some selected kernels. Specifically, we
demonstrate the performance of four sparse kernels, three dense batched
kernels, two graph kernels and one team level algorithm.
