Programming Models for Heterogeneous Systems with Application to Computer Graphics

Abstract

For over a decade, we have seen a plateauing of CPU clock rates, primarily due topower and thermal constraints. To counter these problems, processor architects have turned to both multi-core and heterogeneous processors.Whilst the use of heterogeneous processors provides a route to reducing energy con-sumption, this comes at the cost of increased complexity for software developers.In this thesis, we explore the development of C++-based programming models and frameworks which enable the efficient use of these heterogeneous platforms, and the application of these programming models to problems from the field of visual computing. Two recent specifications for heterogeneous computing: SYCL and Heterogeneous System Architecture, share the common goal of providing a foundation for developing heterogeneous programming models. In this thesis, we provide early evaluations of the suitability of these two new platforms as foundations for building higher-level domain-specific abstractions. We drawing upon two use cases from the field of visual computing: image processing and ray tracing; and explore the development and use of domain-specific C++ abstractions layered upon these platforms.We present a domain-specific language which generates optimized image processing kernels by deeply embedding within SYCL. By combining simple primitives into more complex kernels, we are able to eliminate intermediate memory accesses and improved performance.We also describe Offload for HSA: a single-source C++14 compiler and programming model for Heterogeneous System Architecture. The pervasive shared virtual memory offered by HSA allows us to reduce execution overheads and relax constraints imposed by SYCL’s programming model, leading to significant performance improvements.Performance optimization on heterogeneous systems is a challenging task. We build upon Offload to provide RTKit, a framework for exploring the optimization space of ray tracing algorithms on heterogeneous systems.Finally, we conclude by discussing challenges raised by our work and open problems that must be resolved in order to unify C++ and heterogeneous computing.

Date of Award	1 Jun 2017
Original language	English
Awarding Institution	University of Bath
Sponsors	Codeplay Software Ltd
Supervisor	Russell Bradford (Supervisor)