POSIX等价的boost ::螺纹:: hardware_concurrency的 [英] POSIX equivalent of boost::thread::hardware_concurrency

问题描述

可能重复：结果
  <一href=\"http://stackoverflow.com/questions/150355/programmatically-find-the-number-of-cores-on-a-machine\">Programmatically找到一台机器内核数

什么是POSIX或x86，x86-64的特定系统调用来确定线程的最大数量，系统可以在不超额认购运行吗？谢谢你。

What is the POSIX or x86, x86-64 specific system call to determine the max number of threads the system can run without over-subscription? Thank you.

推荐答案

它采用C兼容的结构，那么为什么不直接使用实际的code？ [库/线程/ src目录/ * / thread.cpp]

It uses C-compatible constructs, so why not just use the actual code? [libs/thread/src/*/thread.cpp]

pthread库：

unsigned thread::hardware_concurrency()
{
#if defined(PTW32_VERSION) || defined(__hpux)
    return pthread_num_processors_np();
#elif defined(__APPLE__) || defined(__FreeBSD__)
    int count;
    size_t size=sizeof(count);
    return sysctlbyname("hw.ncpu",&count,&size,NULL,0)?0:count;
#elif defined(BOOST_HAS_UNISTD_H) && defined(_SC_NPROCESSORS_ONLN)
    int const count=sysconf(_SC_NPROCESSORS_ONLN);
    return (count>0)?count:0;
#elif defined(_GNU_SOURCE)
    return get_nprocs();
#else
    return 0;
#endif
}

在窗口：

unsigned thread::hardware_concurrency()
{
    SYSTEM_INFO info={{0}};
    GetSystemInfo(&info);
    return info.dwNumberOfProcessors;
}

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