A Runtime Controller for OpenCL Applications on Heterogeneous System Architectures.

Nowadays Heterogeneous System Architectures (HSAs) are becoming very attractive in the embedded and mobile markets thanks to the possibility to select the best computational resource among the available compute units to optimize the performance per Watt figure of merit. In this scenario, OpenCL is becoming the standard paradigm for heterogeneous computing supporting the programming of all types of units with a single abstraction level. However, the decision of the resource to use together with its architectural tuning is still left to the programmer; this issue is even more exacerbated when considering the fact that the choice depends also on the actual conditions in which the system is operating. This work aims at proposing a runtime controller, integrated in Linux Operating System (OS), for optimizing the power efficiency of a running OpenCL application deciding the system configuration. Our experimental results over a set of applications from the Polybench suite on the Odroid XU3 board show that our controller is able to obtain a power efficiency of more than 90% of the one achievable via offline profiling.