编程找到一台机器上的内核数量 [英] Programmatically find the number of cores on a machine

问题描述

有没有办法来确定一台机器从C / C多少个核心拥有++在平台无关的方式？如果没有这样的东西存在，那它确定每个平台（Windows / * nix中/苹果机）？

解决方案

C ++ 11

  //可能会返回0时无法检测
无符号concurentThreadsSupported =的std ::螺纹:: hardware_concurrency（）;
 

参考：<一href=\"http://en.cp$p$pference.com/w/cpp/thread/thread/hardware_concurrency\">std::thread::hardware_concurrency

---

在C ++ C ++前11，没有可移植的方法。相反，你需要使用下列方法之一以上（通过适当的守卫 #IFDEF 行）：

• 的Win32

    SYSTEM_INFO SYSINFO;
  的GetSystemInfo（安培; SYSINFO）;
  INT numCPU = sysinfo.dwNumberOfProcessors;
   




• Linux，Solaris和AIX和Mac OS X> = 10.4（即虎起）

    INT numCPU =的sysconf（_SC_NPROCESSORS_ONLN）;
   




• FreeBSD的，MacOS X系统，NetBSD的，OpenBSD的，等等。

    INT MIB [4];
  INT numCPU;
  的std ::为size_t的len = sizeof的（numCPU）;/ *设置的MIB hw.ncpu * /
  MIB [0] = CTL_HW;
  MIB [1] = HW_AVAILCPU; //或者，尝试HW_NCPU;/ *从系统中获得的CPU的数量* /
  的sysctl（MIB，2，＆放大器; numCPU，＆放大器; len个，NULL，0）;如果（numCPU＆。1）
  {
      MIB [1] = HW_NCPU;
      的sysctl（MIB，2，＆放大器; numCPU，＆放大器; len个，NULL，0）;
      如果（numCPU＆。1）
          numCPU = 1;
  }
   




• HPUX

    INT numCPU = mpctl（MPC_GETNUMSPUS，NULL，NULL）;
   




• IRIX

    INT numCPU =的sysconf（_SC_NPROC_ONLN）;
   




• 的Objective-C键（Mac OS X> = 10.5或iOS）

    NSUInteger A = [[NSProcessInfo processInfo] processorCount]
  NSUInteger B = [[NSProcessInfo processInfo] activeProcessorCount];
   

Is there a way to determine how many cores a machine has from C/C++ in a platform-independent way? If no such thing exists, what about determining it per-platform (Windows/*nix/Mac)?

解决方案

C++11

//may return 0 when not able to detect
unsigned concurentThreadsSupported = std::thread::hardware_concurrency();

Reference: std::thread::hardware_concurrency

---

In C++ prior to C++11, there's no portable way. Instead, you'll need to use one or more of the following methods (guarded by appropriate #ifdef lines):

• Win32

  SYSTEM_INFO sysinfo;
  GetSystemInfo(&sysinfo);
  int numCPU = sysinfo.dwNumberOfProcessors;
  

• Linux, Solaris, AIX and Mac OS X >=10.4 (i.e. Tiger onwards)

  int numCPU = sysconf(_SC_NPROCESSORS_ONLN);
  

• FreeBSD, MacOS X, NetBSD, OpenBSD, etc.

  int mib[4];
  int numCPU;
  std::size_t len = sizeof(numCPU); 
  
  /* set the mib for hw.ncpu */
  mib[0] = CTL_HW;
  mib[1] = HW_AVAILCPU;  // alternatively, try HW_NCPU;
  
  /* get the number of CPUs from the system */
  sysctl(mib, 2, &numCPU, &len, NULL, 0);
  
  if (numCPU < 1) 
  {
      mib[1] = HW_NCPU;
      sysctl(mib, 2, &numCPU, &len, NULL, 0);
      if (numCPU < 1)
          numCPU = 1;
  }
  

• HPUX

  int numCPU = mpctl(MPC_GETNUMSPUS, NULL, NULL);
  

• IRIX

  int numCPU = sysconf(_SC_NPROC_ONLN);
  

• Objective-C (Mac OS X >=10.5 or iOS)

  NSUInteger a = [[NSProcessInfo processInfo] processorCount];
  NSUInteger b = [[NSProcessInfo processInfo] activeProcessorCount];
  

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