如何确保在多核中创建std :: thread？ [英] How to ensure that std::thread are created in multi core?

问题描述

我使用visual studio 2012.我有一个模块，在那里，我必须从硬盘读取一大组文件，穿过它们相应的路径通过xml。为此我正在做

  std :: vector< std :: thread> m_ThreadList; 
 

在while循环中，我将一个新线程推回到这个向量中，例如

  m_ThreadList.push_back（std :: thread（& MyClass :: Readfile，& MyClassObject，filepath，std :: ref（polygon）） ）; 
  

我的C ++ 11多线程知识是有限的。我在这里的问题是，做在特定的核心上创建线程？我知道在vs2012中的parallel_for和parallel_for_each，使最佳使用的内核。但是，有没有办法这样做使用标准的C ++ 11？

解决方案

正如其他评论指出，在特定核心上创建线程，因为C ++不知道这样的架构细节。此外，在大多数情况下，操作系统将能够足够好地管理核心/处理器之间的线程分布。

也就是说，存在这样的情况，其中强制在核心之间的线程的特定分布可以有益于性能。作为示例，通过强制线程在一个特定核上执行，可以最小化不同处理器缓存之间的数据移动（这对于在某些存储器限制情况下的性能是至关重要的）。

如果你想走这条路，你必须看看平台特定的例程。例如，对于带有POSIX线程的GNU / linux，您将需要在FreeBSD cpuset_setaffinity（）中的 pthread_setaffinity_np（） SetThreadAffinityMask（）等。

如果你有兴趣，我有一些相关的代码片段：

http：// gitorious。 org / piranhapp0x / mainline / blobs / master / src / thread_management.cpp

I am using visual studio 2012. I have a module, where, I have to read a huge set of files from the hard disk after traversing their corresponding paths through an xml. For this i am doing

std::vector<std::thread> m_ThreadList;

In a while loop I am pushing back a new thread into this vector, something like

m_ThreadList.push_back(std::thread(&MyClass::Readfile, &MyClassObject, filepath,std::ref(polygon)));

My C++11 multi threading knowledge is limited.The question that I have here , is , how do create a thread on a specific core ? I know of parallel_for and parallel_for_each in vs2012, that make optimum use of the cores. But, is there a way to do this using standard C++11?

解决方案

As pointed out in other comments, you cannot create a thread "on a specific core", as C++ has no knowledge of such architectural details. Moreover, in the majority of cases, the operating system will be able to manage the distribution of threads among cores/processors well enough.

That said, there exist cases in which forcing a specific distribution of threads among cores can be beneficial for performance. As an example, by forcing a thread to execute onto a one specific core it might be possible to minimise data movement between different processor caches (which can be critical for performance in certain memory-bound scenarios).

If you want to go down this road, you will have to look into platform-specific routines. E.g., for GNU/linux with POSIX threads you will want pthread_setaffinity_np(), in FreeBSD cpuset_setaffinity(), in Windows SetThreadAffinityMask(), etc.

I have some relevant code snippets here if you are interested:

http://gitorious.org/piranhapp0x/mainline/blobs/master/src/thread_management.cpp

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