Abstract: Data processing in a hybrid computing environment that includes a host computer and an accelerator, the host and the accelerator adapted to one another for data communications by a system level message passing module and a plurality data communications fabrics of at least two different fabric types, the data processing including: monitoring data communications performance for a plurality of data communications modes; receiving, from an application program on the host computer, a request to transmit data according to a data communications mode from the host computer to the accelerator; determining, in dependence upon the monitored performance, whether to transmit the data according to the requested data communications mode; and if the data is not to be transmitted according to the requested data communications mode: selecting, in dependence upon the monitored performance, another data communications mode for transmitting the data and transmitting the data according to the selected data communications mode.