Question

这里的例子有:

#include <iostream>
#include <list>
#include <tbb/task.h>
#include <tbb/task_group.h>
#include <stdlib.h>
#include <boost/thread.hpp>

using namespace tbb;

 long fib(long a)
{
  if (a < 2) return 1;

  return fib(a - 1) + fib(a - 2);
}

class PrintTask 
{
public:
    void operator()()
    {
        std::cout << "hi world!: " <<  boost::this_thread::get_id() << std::endl;

        fib(50);
    }
};

int main(int argc, char** argv)
{     
    task_group group;

    for (int i = 0; i < 100; ++i)
    {
      group.run(PrintTask());
    }      

    group.wait();

    return(0);
}

在此,我计算一个大的纤维素序列,只是模拟非锁定的计算。我猜测,这部法典将产生两个以上的线索(我的计算机是核心2Duo),但只要求开展第一和第二项任务。这是猜测的吗?

Answer 1

是的,这是预期的行为。

TBB是一家图书馆,旨在把手工业守则相平行。官方文件指出,你应当利用另一个图书馆(例如校对)来完成这些任务(或加强:在你看来已经准备好)。

就最大限度的绩效而言,与你的核心相比,没有什么意义,因为涉及一些重大间接费用(不仅仅是环境变化,而且还包括冲积海滩等)。

EDIT: You can read about it in the Tutorial. Specifically, in section 1.2 "Benefits" it states

Intel® Threading Building Blocks targets threading for performance. Most general-purpose threading packages support many different kinds of threading, such as threading for asynchronous events in graphical user interfaces. As a result, general-purpose packages tend to be low-level tools that provide a foundation, not a solution. Instead, Intel® Threading Building Blocks focuses on the particular goal of parallelizing computationally intensive work, delivering higher-level, simpler solutions.

以及

Intel® Threading Building Blocks is compatible with other threading packages. Because the library is not designed to address all threading problems, it can coexist seamlessly with other threading packages.

Answer 2

大规模多面阻塞行为(结果:滥用)是多处的反家长,可能会造成不良行为,因为它会错失。此外,TBB保留了实施集团的权利,然而,无论它喜欢什么东西,它都会pa。如果你只拥有双重核心,而且你要求开展繁重的工作,那么它为什么会铺开两条以上线? 职业顾问办公室和其他用具将 ha忙地用剩余的背景时间。

友情链接