使用intel提供的多线程函数

低调华龙 2008-08-05 09:57:55

在实际中使用过intel提供的多线程函数，今天看了他的getting starting.pdf,看了半天也没看明白是怎么用的，请使用过的大师给介绍介绍啊，它是用c++实现的，不知道用c可以不，请指教，当然在使用过程中有什么好的建议或要注意的地饭或者有代码的话请给我点
我学习下
谢谢！
以下是代码：
#include <iostream>
#include <string>
#include <algorithm>
#include "tbb/task_scheduler_init.h"
#include "tbb/parallel_for.h"
#include "tbb/blocked_range.h"
#include "tbb/tick_count.h"

using namespace tbb;
using namespace std;
static const size_t N = 22;

void SerialSubStringFinder ( const string &str, size_t *max_array, size_t *pos_array) {
for ( size_t i = 0; i < str.size(); ++i ) {
size_t max_size = 0, max_pos = 0;
for (size_t j = 0; j < str.size(); ++j)
if (j != i) {
size_t limit = str.size()-( i > j ? i : j );
for (size_t k = 0; k < limit; ++k) {
if (str[i + k] != str[j + k]) break;
if (k > max_size) {
max_size = k;
max_pos = j;
}
}
}
max_array[i] = max_size;
pos_array[i] = max_pos;
}
}

class SubStringFinder {
const string str;
size_t *max_array;
size_t *pos_array;
public:
void operator() ( const blocked_range<size_t>& r ) const {
for ( size_t i = r.begin(); i != r.end(); ++i ) {
size_t max_size = 0, max_pos = 0;
for (size_t j = 0; j < str.size(); ++j)
if (j != i) {
size_t limit = str.size()-( i > j ? i : j );
for (size_t k = 0; k < limit; ++k) {
if (str[i + k] != str[j + k]) break;
if (k > max_size) {
max_size = k;
max_pos = j;
}
}
}
max_array[i] = max_size;
pos_array[i] = max_pos;
}
}
SubStringFinder(string &s, size_t *m, size_t *p) :
str(s), max_array(m), pos_array(p) { }
};

int main(size_t argc, char *argv[]) {
task_scheduler_init init;

string str[N] = { string("a"), string("b") };
for (size_t i = 2; i < N; ++i) str[i] = str[i-1]+str[i-2];
string &to_scan = str[N-1];

size_t *max = new size_t[to_scan.size()];
size_t *max2 = new size_t[to_scan.size()];
size_t *pos = new size_t[to_scan.size()];
size_t *pos2 = new size_t[to_scan.size()];
cout << " Done building string." << endl;

tick_count serial_t0 = tick_count::now();
SerialSubStringFinder(to_scan, max2, pos2);
tick_count serial_t1 = tick_count::now();
cout << " Done with serial version." << endl;

tick_count parallel_t0 = tick_count::now();
parallel_for(blocked_range<size_t>(0, to_scan.size(), 100),
SubStringFinder( to_scan, max, pos ) );
tick_count parallel_t1 = tick_count::now();
cout << " Done with parallel version." << endl;

for (size_t i = 0; i < to_scan.size(); ++i) {
if (max[i] != max2[i] || pos[i] != pos2[i]) {
cout << "ERROR: Serial and Parallel Results are Different!" << endl;
}
}
cout << " Done validating results." << endl;

cout << "Serial version ran in " << (serial_t1 - serial_t0).seconds() << " seconds" << endl
<< "Parallel version ran in " << (parallel_t1 - parallel_t0).seconds() << " seconds" << endl
<< "Resulting in a speedup of " << (serial_t1 - serial_t0).seconds() / (parallel_t1 - parallel_t0).seconds() << endl;
return 0;
}

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