Gcc openmp中的两个内环优化
我花了一些时间在嵌套循环上玩openmp,但是,如果有2+个内部循环,我就无法让它工作。是否可以在2+个内部循环上使用openmp pragmas,而不使用条件语句将其重写回1Gcc openmp中的两个内环优化,gcc,parallel-processing,openmp,Gcc,Parallel Processing,Openmp,我花了一些时间在嵌套循环上玩openmp,但是,如果有2+个内部循环,我就无法让它工作。是否可以在2+个内部循环上使用openmp pragmas,而不使用条件语句将其重写回1 for (i = 1; i <= n; i++) { for (w = 0; w <= in[i][W]; w++) a[i][w] = a[i-1][w]; for (w = in[i][W]+1; w <= wc; w++) a[i][w] = max(a[i-1][w],
for (i = 1; i <= n; i++)
{
for (w = 0; w <= in[i][W]; w++)
a[i][w] = a[i-1][w];
for (w = in[i][W]+1; w <= wc; w++)
a[i][w] = max(a[i-1][w], in[i][V] + a[i-1][w-in[i][W]]);
}
你想达到什么目标?你为什么希望内部循环分开 是什么让你认为并行化内部循环有什么好处 将它们并行化到底有什么问题 什么是V,W和in?V和W都是常数;W=0,V=1,所以很明显阵列的大小是2n+1
#include <omp.h>
int main()
{
for (int i=0; i <100; ++i)
{
int m = 5000;
#pragma omp parallel for
for (int j=0; j<m; ++j)
{
}
#pragma omp parallel for
for (int j=m; j<2*m; ++j)
{
}
}
}
#include <omp.h>
#include <iostream>
int main()
{
int id = 0;
#pragma omp parallel
{
int m = 5000;
std::cout << "parallel section #" << ++id << "\n";
{
#pragma omp single
std::cout << "first single section\n";
for (int j=0; j<m; ++j)
{
}
}
{
#pragma omp single
std::cout << "second single section\n";
for (int j=m; j<2*m; ++j)
{
}
}
}
}
parallel section #1
parallel section #2
first single section
parallel section #3
parallel section #4
second single section