  Today, one of the main challenges for high-performance computing systems is
to improve their performance by keeping energy consumption at acceptable
levels. In this context, a consolidated strategy consists of using accelerators
such as GPUs or many-core Intel Xeon Phi processors. In this work, devices of
the NVIDIA Pascal and Intel Xeon Phi Knights Landing architectures are
described and compared. Selecting the Floyd-Warshall algorithm as a
representative case of graph and memory-bound applications, optimized
implementations were developed to analyze and compare performance and energy
efficiency on both devices. As it was expected, Xeon Phi showed superior when
considering double-precision data. However, contrary to what was considered in
our preliminary analysis, it was found that the performance and energy
efficiency of both devices were comparable using single-precision datatype.
