wiki:YMU110509/Lab2

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實作二

多核心程式設計 : OpenMP
Multi-Cores Programming : OpenMP

編譯環境檢驗 Compiler Version Check

  • GCC 4.2 以上版本就有支援 OpenMP 了....用 "gcc -fopenmp" 就可以編譯
  • 確認目前 gcc 版本,須大於 4.2 以後的版本
    ~$ gcc -v
    Using built-in specs.
    Target: x86_64-linux-gnu
    Configured with: ../src/configure -v --with-pkgversion='Debian 4.4.5-8' --with-bugurl=file:///usr/share/doc/gcc-4.4/README.Bugs --enable-languages=c,c++,fortran,objc,obj-c++ --prefix=/usr --program-suffix=-4.4 --enable-shared --enable-multiarch --enable-linker-build-id --with-system-zlib --libexecdir=/usr/lib --without-included-gettext --enable-threads=posix --with-gxx-include-dir=/usr/include/c++/4.4 --libdir=/usr/lib --enable-nls --enable-clocale=gnu --enable-libstdcxx-debug --enable-objc-gc --with-arch-32=i586 --with-tune=generic --enable-checking=release --build=x86_64-linux-gnu --host=x86_64-linux-gnu --target=x86_64-linux-gnu
    Thread model: posix
    gcc version 4.4.5 (Debian 4.4.5-8) 
    

Example 1 : HelloWorld

  • 首先從 OpenMP Exercise 下載 omp_hello.c
    ~$ wget https://computing.llnl.gov/tutorials/openMP/samples/C/omp_hello.c
    
  • 使用 GCC 編譯 omp_hello.c
    ~$ gcc -o omp_hello -fopenmp omp_hello.c
    
  • 執行 omp_hello 執行檔
    ~$ ./omp_hello 
    Hello World from thread = 2
    Hello World from thread = 3
    Hello World from thread = 0
    Number of threads = 4
    Hello World from thread = 1
    

Example 2 : Loop work-sharing

  • 首先從 OpenMP Exercise 下載 omp_workshare1.c
    ~$ wget https://computing.llnl.gov/tutorials/openMP/samples/C/omp_workshare1.c
    
  • 使用 GCC 編譯 omp_workshare1.c
    ~$ gcc -o omp_workshare1 -fopenmp omp_workshare1.c
    
  • 執行 omp_workshare1 執行檔
    ~$ ./omp_workshare1
    ~$ ./omp_workshare1
    Thread 3 starting...
    Thread 1 starting...
    Number of threads = 4
    Thread 0 starting...
    Thread 0: c[20]= 40.000000
    Thread 0: c[21]= 42.000000
    Thread 0: c[22]= 44.000000
    Thread 0: c[23]= 46.000000
    Thread 0: c[24]= 48.000000
    Thread 0: c[25]= 50.000000
    
     ... skipped ... 
    
    Thread 2 starting...
    Thread 2: c[90]= 180.000000
    Thread 2: c[91]= 182.000000
    Thread 2: c[92]= 184.000000
    Thread 2: c[93]= 186.000000
    Thread 2: c[94]= 188.000000
    
     ... skipped ... 
    
    Thread 3: c[0]= 0.000000
    Thread 3: c[1]= 2.000000
    Thread 3: c[2]= 4.000000
    Thread 3: c[3]= 6.000000
    Thread 3: c[4]= 8.000000
    Thread 3: c[5]= 10.000000
     
     ... skipped ... 
    
    Thread 1: c[10]= 20.000000
    Thread 1: c[11]= 22.000000
    Thread 1: c[12]= 24.000000
    Thread 1: c[13]= 26.000000
    Thread 1: c[14]= 28.000000
    
    

OpenMP 參考資料

Perl v.s. multicore

Python v.s. multicore

Last modified 11 years ago Last modified on May 9, 2011, 3:24:19 PM