Fortran OpenMP 并行编程要点总结

总结 Fortran 编写 OpenMP 并行程序的基本要点, 以供后续参考.

Question

Open Multi-processing
C, C++, Fortran
Version
Framework
1. Program Layer: OpenMP library
2. Systeme Layer: OpemMP Runtime library
Heterogeneous 异构 CPU + GPU

Fork-Join Model
1. Master Thread (initial thread)
2. Parallerl Worker Thread (Synchronization)
Difference
1. MPI: Message Passing Interface
2. OpenMP: Multi-thread
Process vs. Thread
1. 软件层面与硬件层面的线程含义不同
2. 软件层面，进程有独立地址空间，一个进程下的线程共享地址空间
3. 硬件层面，超线程 (hyper-threading) 将单个物理核心 (core) 抽象为多个逻辑核心 (thread), 不同的 core 会共享缓存，由此导致任务分配时的线程亲和性和线程绑定问题

1	echo \| cpp -fopenmp -dM \| grep -i open

-openmp

# Find OpemMP
find_package(OpenMP)
add_compile_options(-Wunknown-pragmas)
# link OpenMP
target_link_libraries()

clause	Parallerl	for	Parallerl for
if	$\surd$		$\surd$
num_threads	$\surd$		$\surd$
default	$\surd$		$\surd$
copyin	$\surd$		$\surd$
reduction	$\surd$	$\surd$	$\surd$
shared	$\surd$	$\surd$	$\surd$
private	$\surd$	$\surd$	$\surd$
firstprivate	$\surd$	$\surd$	$\surd$
lastprivate		$\surd$	$\surd$
schedule		$\surd$	$\surd$
ordered		$\surd$	$\surd$
collapse		$\surd$	$\surd$
nowait		$\surd$