📄 37.html

📁 国外MPI教材

💻 HTML

字号:

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en"><head>	<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1" />	<style type="text/css">	body { font-family: Verdana, Arial, Helvetica, sans-serif;}	a.at-term {	font-style: italic; }	</style>	<title>The Master Region</title>	<meta name="Generator" content="ATutor">	<meta name="Keywords" content=""></head><body> <p>The <em>master directive</em> designates a section of code (a structured block) that is executed <em>only</em> by the master thread, i.e., thread 0. This section of code is called the<b> master region</b>.</p>

<p class="codelang">Fortran syntax</p>
  
<pre><code>!$omp master
    <em>structured block</em>
!$omp end master</code></pre>
    
<p class="codelang">C/C++ syntax</p>
 
<code><pre>#pragma omp master
    <em>structured block</em></pre></code>

<p>Other threads simply skip over the master region and proceed to the subsequent code; there is no implicit barrier or other synchronization. The following example 
illustrates the use of the master directive: </p>

<pre><code>!$omp parallel shared(c,scale) &
!$omp private(j,myid)
      myid=omp_get_thread_num()
!$omp master
   print *, 'T:', myid, ' enter scale'
   read *,scale
!$omp end master
!$omp barrier  
!$omp do
   do j = 1, N
      c(j) = scale * c(j)
   enddo
!$omp end do
!$omp end parallel</code></pre>
      

<p>In this case the master thread (only) prompts for and reads the user input. The barrier is necessary to prevent the other threads from proceeding immediately 
to the do loop, before <var>scale</var> has been entered. </p></body></html>

⌨️ 快捷键说明

复制代码 Ctrl + C

搜索代码 Ctrl + F

全屏模式 F11

切换主题 Ctrl + Shift + D

显示快捷键 ?

增大字号 Ctrl + =

减小字号 Ctrl + -