OpenMP와 OpenACC의 관계

이질 계산을 위한 프로그래밍 환경으로서 OpenMP4.0에서 device 설정을 도입하였으며 OpenACC와 비슷한 처리를 설명할 수 있다.
그럼에도 불구하고 OpenMP/OpenACC의 목표 방향성은 미묘하게 다르다.
“The real issue is which one, OpenACC or OpenMP, solves the issue for the users,” explains Wolfe. “OpenMP is richer and has more features than OpenACC, we make no apologies about that. OpenACC is targeting scalable parallelism, OpenMP is targeting more general parallelism including things like tasks, which in some senses are inherently not scalable. OpenMP has a lot more synchronization primitives, and if you are talking about scalable parallelism, that is just a way to slow your program down. The important differences are performance portability – and at SC15 you heard that it is either important or impossible – and we are saying that it is not only important and possible, but that we are demonstrating this today.”
(Wolfe의 입장: technical chair for OpenACC)

( http://www.nextplatform.com/wp-content/uploads/2015/11/openacc-versus-openmp.jpg )
OpenMP 공식
OMPAPI.Relatives.01 How does OpenMP relate to OpenACC ?
OpenMP and OpenACC are actively merging their specification while continuing to evolve. A first step at merging has been made with the release of OpenMP 4.0. OpenACC implementations can be considered to be a beta test of the OpenMP accelerator specification. They give early implementation experience.
OpenACC has been created and implemented by several members of the OpenMP ARB in order to address their immediate customer needs. These members are NVIDIA, PGI, Cray, and CAPS.
OpenACC 공식
What does it take port application OpenACC versus OpenMP
OpenACC and OpenMP require a similar approach to parallelizing code, so no developer investment is wasted.
OpenACC allows the developer to express the parallelism in the code while relying on an OpenACC compiler to map that parallelism to the hardware. This enables the developer to write parallel code that is performance portable to any architecture.
OpenMP relies on the developer to explicitly parallelize their code, which makes OpenMP simpler for a compiler to implement but more difficult to make portable to different architectures.
관련 자료

(PDF) OpenMP and OpenACC a Comparison

(PDF) Comparing OpenACC and OpenMP Performance and Programmability

(PDF) OpenACC 2.0 versus OpenMP 4.0 device constructs

(PDF) Comparing OpenACC 2.5 and OpenMP 4.1

GTC16 - S6410 - Comparing OpenACC 2.5 and OpenMP 4.5