intel tbb 学习笔记

1/* ***********************************************
2Author :111qqz
3mail: renkuanze@sensetime.com
4Created Time :2018年07月18日 星期三 14时20分54秒
5File Name :parallel_for.cpp
6************************************************ */
7#include <iostream>
8#include "tbb/tbb.h"
9#include <chrono>

1const int N=1E9+7;
2float a[N+5];
3void Foo(float &x) { x -= 100; }
4void SerialApplyFoo( float a[], size_t n ) {
5for( size_t i=0; i!=n; ++i )
6Foo(a[i]);
7}

1class ApplyFoo
2{
3    float *const my_a;

1  public:
2    void operator()(const blocked_range<size_t> &r) const
3    {
4        float *a = my_a;
5        for (size_t i = r.begin(); i != r.end(); ++i)
6        {

1            Foo(a[i]);
2            //printf("%.4f\n", a[i]);
3        }
4    }
5    ApplyFoo(float a[]) : my_a(a)
6    {
7    }
8};

1void ParallelApplyFoo(float a[], size_t n)
2{
3    parallel_for(blocked_range<size_t>(0, n), ApplyFoo(a));
4}

1void print(float a[])
2{
3    for (int i = 0; i < N; i++)
4        printf("%.4f%c", a[i], i == 9 ? '\n' : ' ');
5}
6int main()
7{
8    for (int i = 0; i < N; i++)
9        a[i] = 1. * i;

1    //ParallelApplyFoo(a, N);
2    auto t2 = std::chrono::high_resolution_clock::now();
3    std::chrono::duration<double, std::milli> fp_ms = t2 - t1;
4     std::cout << "f() took " << fp_ms.count() << " ms, "<<std::endl;

1    //print(a);
2    return 0;
3}