#pragma omp parallel shared(val) { // Step 1: thread 0 writes the value if ( omp_get_thread_num() == 0 ) { std::cout << "Thread 0 sets the value of \"val\" to 123." << std::endl; val = 123; } // Threads wait each other before progressing to step 2 #pragma omp ...
omp_set_num_threads(4); //设置线程数为4 start = omp_get_wtime();pragma omp parallel shared(sum) //声明sum为共享变量 { int local_sum = 0;int local_start = omp_get_thread_num();int local_end = local_start + N / 4;for (int i = local_start; i < local_end; i+...
double S2 = 0.; #pragma omp parallel for shared(S2) for(int a=0; a<128; a++){ for(int b=0; b<128;b++){ double myterm = (double)a*b; #pragma omp atomic S2 += myterm; } } return S2; } 问题是 #pragma omp atomic 对程序行为没有影响,即使我删除它,也没有任何反应。即使我...
int i; int n = 1000000; double area = 0; double h = 1.0 / n; #pragma omp parallel for shared(n, h) reduction(+:area) for (i = 1; i <= n; i++) { double x = h * (i - 0.5); area += (4.0 / (1.0 + x*x)); } pi = h * area; ...
编译制导指令以#pragma omp 开始,后边跟具体的功能指令,格式如:#pragma omp 指令[子句[,子句] …]。常用的功能指令如下: parallel:用在一个结构块之前,表示这段代码将被多个线程并行执行; for:用于for循环语句之前,表示将循环计算任务分配到多个线程中并行执行,以实现任务分担,必须由编程人员自己保证每次循环之间无...
pragmaompparallel 系统标签: omppragmaopenmptidnthreadsthreads 1 ProgrammingwithSharedMemory Part2 2 OpenMP OpenMP是1990s后期由一群工业界的专家所开发的一个已被 接受的标准。 由一个小型的编译器制导指令集compilerdirectives,一个扩 展的小型库例程libraryroutines,和使用FortranandC/C++基 本语言的环境变量enviro...
#pragma omp嵌套写法 #include<stdio.h>#include<omp.h>#defineCOUNT 4*8#defineN 1000intmain(){inti;inta[N],b[N],c[N];for(i=0;i<N;i++){a[i]=i;b[i]=i;}# num_threads的数量可以写在#pragma里面也可以放在外面,# 先指定线程数,再设定#pragmaomp parallel num_threads(2) shared(a,b...
#pragma omp parallel for[clauses] #pragma MP serial_loop No exact equivalent. You can use #pragma omp master loop #pragma MP serial_loop_nested No exact equivalent. You can use #pragma omp master loopnest Thetasklooppragma can take on one or more of the following optional clauses. ...
#pragma MP serial_loop_nested 无完全等效指令。可以使用 #pragma omp master loopnest tasklooppragma 可带有下列可选子句中的一个或多个子句。 taskloop taskloop子句 等效的 OpenMPparallelfor子句 schedtype(spec)子句接受下列调度规范。 SCHEDTYPE schedule...
must be shared in the enclosing context. must not be const-qualified. must not have pointer type. orderedSpecify this clause if an ordered construct is present within the dynamic extent of theomp fordirective. schedule (type)Specifies how iterations of theforloop are divided among available threa...