Accelerate the preprocess procedure by parallelization about perigee HOT 11 CLOSED

I have parallelize part of following functions in a new branch [openmp-dev-linux] of repo called M3C-Lab/PERIGEE-viv2022:

• GmshFIleIO::write_vtp() in M3C-Lab/PERIGEE-viv2022/src/Mesh/
• GmshFileIO::write_each_vtu() in M3C-Lab/PERIGEE-viv2022/src/Mesh/
• Part_Tet::Generate_Partition() in M3C-Lab/PERIGEE-viv2022/src/Mesh/
• NodalBC_3D_FSI::NodalBC_3D_FSI() in M3C-Lab/PERIGEE-viv2022/examples/tet4_fsi/src/
• NodalBC_3D_vtu::NodalBC_3D_vtu() in M3C-Lab/PERIGEE-viv2022/src/Mesh/.

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• openmp的计时功能
• openmp的配置
• openmp的报错信息处理

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https://cliutils.gitlab.io/modern-cmake/chapters/packages/OpenMP.html

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https://stackoverflow.com/questions/49816206/cmake-find-package-specify-path

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https://stackoverflow.com/questions/56166109/detect-at-runtime-if-openmp-is-being-used-in-a-c-program

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使用cmake自带的FindOpenMP.cmake进行配置，在system_lib_loading.cmake内修改

• 添加：

set(OpenMP_ROOT /Users/chongran/lib/lib-omp)

find_package(OpenMP REQUIRED)

include_directories(${OpenMP_CXX_INCLUDE_DIR})

set(EXTRA_LINK_LIBS ${EXTRA_LINK_LIBS} ${OpenMP_CXX_LIBRARIES})

if(OPENMP_CXX_FOUND) 
  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${OpenMP_CXX_FLAGS}")
endif()

• 修改：

if( ${CMAKE_BUILD_TYPE} MATCHES "Release" )
  set(CMAKE_CXX_FLAGS " -O3 -Wall ")
else( ${CMAKE_BUILD_TYPE} MATCHES "Release" )
  set(CMAKE_CXX_FLAGS " -DENABLE_TEST -O0 -Wall ")
endif( ${CMAKE_BUILD_TYPE} MATCHES "Release" )

变为

if( ${CMAKE_BUILD_TYPE} MATCHES "Release" )
  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -O3 -Wall ")
else( ${CMAKE_BUILD_TYPE} MATCHES "Release" )
  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -DENABLE_TEST -O0 -Wall ")
endif( ${CMAKE_BUILD_TYPE} MATCHES "Release" )

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Conditional use of OpenMP

https://stackoverflow.com/questions/56717411/control-conditional-openmp-in-define-macro

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https://stackoverflow.com/questions/45477355/difference-between-pragma-and-pragma-in-c

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https://www.dealii.org/current/doxygen/deal.II/config_8h_source.html

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我们或许可以调控对每个exeutable文件的编译flag，参考这个
https://stackoverflow.com/questions/24238937/how-to-change-a-compiler-flag-for-just-one-executable-in-cmake

@ZhaoChongran

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[] 我们还需要在程序里面设置omp_num_threads，避免环境变量里面没有设置这个参数。

[] 我们需要在Sys_Tools中加入一个 print函数 能够把当前的线程个数打印出来。

@ZhaoChongran

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