奔腾双核的电脑，对一个DO循环 使用openmp后，运算时间只是提高了10％
相当的困惑不解，理论上应该是接近50％的呀 


 1 
  2         PROGRAM test_select_sort
  3 !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
  4 ! Purpose: To test the subroutine or function select_sort                       !
  5 ! Record of revisions:                                                          !
  6 !   Date       Programer           Description of changes                       !
  7 ! ==========  ==========      =================================                 !
  8 ! 2011.3.18     Joshua         Original                                         !   
  9 !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!   
 10         !Data dictionary
 11         INTEGER,PARAMETER::N=180
 12         REAL,DIMENSION(N)::array=&
 13                 (/-10,1,2,34,5,5,678,345,90, 567,34,23,7,8,2,5,4,9 &
 14                 ,-10,1,2,34,5,5,678,345,90, 567,34,23,7,8,2,5,4,9 &
 15                 ,-10,1,2,34,5,5,678,345,90, 567,34,23,7,8,2,5,4,9 &
 16                 ,-10,1,2,34,5,5,678,345,90, 567,34,23,7,8,2,5,4,9 &
 17                 ,-10,1,2,34,5,5,678,345,90, 567,34,23,7,8,2,5,4,9 &
 18                 ,-10,1,2,34,5,5,678,345,90, 567,34,23,7,8,2,5,4,9 &
 19                 ,-10,1,2,34,5,5,678,345,90, 567,34,23,7,8,2,5,4,9 &
 20                 ,-10,1,2,34,5,5,678,345,90, 567,34,23,7,8,2,5,4,9 &
 21                 ,-10,1,2,34,5,5,678,345,90, 567,34,23,7,8,2,5,4,9 &
 22                 ,-10,1,2,34,5,5,678,345,90, 567,34,23,7,8,2,5,4,9/)
 23 
 24         REAL::time_start, time_end
 25         !
 26         INTERFACE
 27                 SUBROUTINE select_sort(array, n, c)
 28                 IMPLICIT NONE
 29                 INTEGER, INTENT(IN)::n
 30                 REAL, DIMENSION(n),INTENT(INOUT)::array
 31                 CHARACTER,INTENT(IN)::c
 32                 END SUBROUTINE select_sort
 33         END INTERFACE
 34 
 35         CALL CPU_TIME(time_start)
 36         !$OMP PARALLEL
 37         !$OMP DO
 38                    DO i=1,1000000
 39          !               WRITE(*,*) i
 40                         CALL select_sort(array,N, 'd')
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