349

有没有办法通过.NET/C#找出 CPU 内核的数量？

PS 这是一个直接的代码问题，而不是“我应该使用多线程吗？” 问题！:-)

4

12 回答 12

505

您可以获得与处理器相关的多种不同信息：

  1. 物理处理器数量
  2. 核心数
  3. 逻辑处理器的数量。

这些都可以不同；对于具有 2 个支持双核超线程的处理器的机器，有 2 个物理处理器、4 个内核和 8 个逻辑处理器。

逻辑处理器的数量可通过Environment类获得，但其他信息只能通过WMI获得（并且您可能必须安装一些修补程序或服务包才能在某些系统上获得它）：

确保在项目中添加对 System.Management.dll 的引用。 在 .NET Core 中，它作为 NuGet 包提供（仅适用于 Windows）。

物理处理器：

foreach (var item in new System.Management.ManagementObjectSearcher("Select * from Win32_ComputerSystem").Get())
{
    Console.WriteLine("Number Of Physical Processors: {0} ", item["NumberOfProcessors"]);
}

核心：

int coreCount = 0;
foreach (var item in new System.Management.ManagementObjectSearcher("Select * from Win32_Processor").Get())
{
    coreCount += int.Parse(item["NumberOfCores"].ToString());
}
Console.WriteLine("Number Of Cores: {0}", coreCount);

逻辑处理器：

Console.WriteLine("Number Of Logical Processors: {0}", Environment.ProcessorCount);

或者

foreach (var item in new System.Management.ManagementObjectSearcher("Select * from Win32_ComputerSystem").Get())
{
    Console.WriteLine("Number Of Logical Processors: {0}", item["NumberOfLogicalProcessors"]);
}

从 Windows 中排除的处理器：

您还可以使用setupapi.dll中的 Windows API 调用来发现已从 Windows 中排除（例如通过引导设置）并且使用上述方法无法检测到的处理器。下面的代码给出了现有的逻辑处理器的总数（我无法弄清楚如何区分物理处理器和逻辑处理器），包括那些已从 Windows 中排除的处理器：

static void Main(string[] args)
{
    int deviceCount = 0;
    IntPtr deviceList = IntPtr.Zero;
    // GUID for processor classid
    Guid processorGuid = new Guid("{50127dc3-0f36-415e-a6cc-4cb3be910b65}");

    try
    {
        // get a list of all processor devices
        deviceList = SetupDiGetClassDevs(ref processorGuid, "ACPI", IntPtr.Zero, (int)DIGCF.PRESENT);
        // attempt to process each item in the list
        for (int deviceNumber = 0; ; deviceNumber++)
        {
            SP_DEVINFO_DATA deviceInfo = new SP_DEVINFO_DATA();
            deviceInfo.cbSize = Marshal.SizeOf(deviceInfo);

            // attempt to read the device info from the list, if this fails, we're at the end of the list
            if (!SetupDiEnumDeviceInfo(deviceList, deviceNumber, ref deviceInfo))
            {
                deviceCount = deviceNumber;
                break;
            }
        }
    }
    finally
    {
        if (deviceList != IntPtr.Zero) { SetupDiDestroyDeviceInfoList(deviceList); }
    }
    Console.WriteLine("Number of cores: {0}", deviceCount);
}

[DllImport("setupapi.dll", SetLastError = true)]
private static extern IntPtr SetupDiGetClassDevs(ref Guid ClassGuid,
    [MarshalAs(UnmanagedType.LPStr)]String enumerator,
    IntPtr hwndParent,
    Int32 Flags);

[DllImport("setupapi.dll", SetLastError = true)]
private static extern Int32 SetupDiDestroyDeviceInfoList(IntPtr DeviceInfoSet);

[DllImport("setupapi.dll", SetLastError = true)]
private static extern bool SetupDiEnumDeviceInfo(IntPtr DeviceInfoSet,
    Int32 MemberIndex,
    ref SP_DEVINFO_DATA DeviceInterfaceData);

[StructLayout(LayoutKind.Sequential)]
private struct SP_DEVINFO_DATA
{
    public int cbSize;
    public Guid ClassGuid;
    public uint DevInst;
    public IntPtr Reserved;
}

private enum DIGCF
{
    DEFAULT = 0x1,
    PRESENT = 0x2,
    ALLCLASSES = 0x4,
    PROFILE = 0x8,
    DEVICEINTERFACE = 0x10,
}
于 2010-04-19T20:22:47.250 回答
223 
Environment.ProcessorCount

[文档]

于 2009-10-09T07:00:19.853 回答
38

WMI 查询很慢，因此请尝试仅选择所需的成员，而不是使用 Select *。

以下查询需要 3.4 秒：

foreach (var item in new System.Management.ManagementObjectSearcher("Select * from Win32_Processor").Get())

虽然这个需要 0.122 秒：

foreach (var item in new System.Management.ManagementObjectSearcher("Select NumberOfCores from Win32_Processor").Get())
于 2013-04-19T09:46:51.757 回答
19

Environment.ProcessorCount应该为您提供本地计算机上的核心数。

于 2009-10-09T07:02:09.257 回答
10

最简单的方法 = Environment.ProcessorCount
Environment.ProcessorCount属性的示例

using System;

class Sample 
{
    public static void Main() 
    {
        Console.WriteLine("The number of processors " +
            "on this computer is {0}.", 
            Environment.ProcessorCount);
    }
}
于 2018-02-22T06:33:11.710 回答
10

至少可以说，看看 .NET 如何在内部实现这一点是相当有趣的……它就像“简单”一样，如下所示：

namespace System.Threading
{
    using System;
    using System.Runtime.CompilerServices;

    internal static class PlatformHelper
    {
        private const int PROCESSOR_COUNT_REFRESH_INTERVAL_MS = 0x7530;
        private static volatile int s_lastProcessorCountRefreshTicks;
        private static volatile int s_processorCount;

        internal static bool IsSingleProcessor
        {
            get
            {
                return (ProcessorCount == 1);
            }
        }

        internal static int ProcessorCount
        {
            get
            {
                int tickCount = Environment.TickCount;
                int num2 = s_processorCount;
                if ((num2 == 0) || ((tickCount - s_lastProcessorCountRefreshTicks) >= 0x7530))
                {
                    s_processorCount = num2 = Environment.ProcessorCount;
                    s_lastProcessorCountRefreshTicks = tickCount;
                }
                return num2;
            }
        }
    }
}
于 2015-11-23T13:56:44.967 回答
4

来自 .NET 框架源

您也可以使用PInvoke获取它Kernel32.dll

以下代码或多或少来自位于此处SystemInfo.cs的 System.Web 源：

[StructLayout(LayoutKind.Sequential, Pack = 1)]
public struct SYSTEM_INFO
{
  public ushort wProcessorArchitecture;
  public ushort wReserved;
  public uint dwPageSize;
  public IntPtr lpMinimumApplicationAddress;
  public IntPtr lpMaximumApplicationAddress;
  public IntPtr dwActiveProcessorMask;
  public uint dwNumberOfProcessors;
  public uint dwProcessorType;
  public uint dwAllocationGranularity;
  public ushort wProcessorLevel;
  public ushort wProcessorRevision;
}

internal static class SystemInfo 
{
    static int _trueNumberOfProcessors;
    internal static readonly IntPtr INVALID_HANDLE_VALUE = new IntPtr(-1);    

    [DllImport("kernel32.dll", CharSet = CharSet.Unicode)]
    internal static extern void GetSystemInfo(out SYSTEM_INFO si);

    [DllImport("kernel32.dll")]
    internal static extern int GetProcessAffinityMask(IntPtr handle, out IntPtr processAffinityMask, out IntPtr systemAffinityMask);

    internal static int GetNumProcessCPUs()
    {
      if (SystemInfo._trueNumberOfProcessors == 0)
      {
        SYSTEM_INFO si;
        GetSystemInfo(out si);
        if ((int) si.dwNumberOfProcessors == 1)
        {
          SystemInfo._trueNumberOfProcessors = 1;
        }
        else
        {
          IntPtr processAffinityMask;
          IntPtr systemAffinityMask;
          if (GetProcessAffinityMask(INVALID_HANDLE_VALUE, out processAffinityMask, out systemAffinityMask) == 0)
          {
            SystemInfo._trueNumberOfProcessors = 1;
          }
          else
          {
            int num1 = 0;
            if (IntPtr.Size == 4)
            {
              uint num2 = (uint) (int) processAffinityMask;
              while ((int) num2 != 0)
              {
                if (((int) num2 & 1) == 1)
                  ++num1;
                num2 >>= 1;
              }
            }
            else
            {
              ulong num2 = (ulong) (long) processAffinityMask;
              while ((long) num2 != 0L)
              {
                if (((long) num2 & 1L) == 1L)
                  ++num1;
                num2 >>= 1;
              }
            }
            SystemInfo._trueNumberOfProcessors = num1;
          }
        }
      }
      return SystemInfo._trueNumberOfProcessors;
    }
}
于 2016-03-02T12:05:12.923 回答
2

这里已经有很多答案，但有些答案很重，而且是不正确的。

.NET Environment.ProcessorCount 将返回不正确的值，如果您的系统 WMI 配置不正确，可能会严重失败。

如果您想要一种可靠的方法来计算内核，唯一的方法是 Win32 API。

这是一个 C++ 片段：

#include <Windows.h>
#include <vector>

int num_physical_cores()
{
    static int num_cores = []
    {
        DWORD bytes = 0;
        GetLogicalProcessorInformation(nullptr, &bytes);
        std::vector<SYSTEM_LOGICAL_PROCESSOR_INFORMATION> coreInfo(bytes / sizeof(SYSTEM_LOGICAL_PROCESSOR_INFORMATION));
        GetLogicalProcessorInformation(coreInfo.data(), &bytes);

        int cores = 0;
        for (auto& info : coreInfo)
        {
            if (info.Relationship == RelationProcessorCore)
                ++cores;
        }
        return cores > 0 ? cores : 1;
    }();
    return num_cores;
}

由于这是一个 .NET C# 问题，这里是移植版本：

[StructLayout(LayoutKind.Sequential)]
struct CACHE_DESCRIPTOR
{
    public byte Level;
    public byte Associativity;
    public ushort LineSize;
    public uint Size;
    public uint Type;
}

[StructLayout(LayoutKind.Explicit)]
struct SYSTEM_LOGICAL_PROCESSOR_INFORMATION_UNION
{
    [FieldOffset(0)] public byte ProcessorCore;
    [FieldOffset(0)] public uint NumaNode;
    [FieldOffset(0)] public CACHE_DESCRIPTOR Cache;
    [FieldOffset(0)] private UInt64 Reserved1;
    [FieldOffset(8)] private UInt64 Reserved2;
}

public enum LOGICAL_PROCESSOR_RELATIONSHIP
{
    RelationProcessorCore,
    RelationNumaNode,
    RelationCache,
    RelationProcessorPackage,
    RelationGroup,
    RelationAll = 0xffff
}

struct SYSTEM_LOGICAL_PROCESSOR_INFORMATION
{
    public UIntPtr ProcessorMask;
    public LOGICAL_PROCESSOR_RELATIONSHIP Relationship;
    public SYSTEM_LOGICAL_PROCESSOR_INFORMATION_UNION ProcessorInformation;
}

[DllImport("kernel32.dll")]
static extern unsafe bool GetLogicalProcessorInformation(SYSTEM_LOGICAL_PROCESSOR_INFORMATION* buffer, out int bufferSize);

static unsafe int GetProcessorCoreCount()
{
    GetLogicalProcessorInformation(null, out int bufferSize);
    int numEntries = bufferSize / sizeof(SYSTEM_LOGICAL_PROCESSOR_INFORMATION);
    var coreInfo = new SYSTEM_LOGICAL_PROCESSOR_INFORMATION[numEntries];

    fixed (SYSTEM_LOGICAL_PROCESSOR_INFORMATION* pCoreInfo = coreInfo)
    {
        GetLogicalProcessorInformation(pCoreInfo, out bufferSize);
        int cores = 0;
        for (int i = 0; i < numEntries; ++i)
        {
            ref SYSTEM_LOGICAL_PROCESSOR_INFORMATION info = ref pCoreInfo[i];
            if (info.Relationship == LOGICAL_PROCESSOR_RELATIONSHIP.RelationProcessorCore)
                ++cores;
        }
        return cores > 0 ? cores : 1;
    }
}

public static readonly int NumPhysicalCores = GetProcessorCoreCount();
于 2020-09-04T16:28:56.040 回答
1

一种选择是从注册表中读取数据。MSDN 文章主题： http: //msdn.microsoft.com/en-us/library/microsoft.win32.registry.localmachine (v=vs.71).aspx )

处理器，我相信可以位于此处，HKEY_LOCAL_MACHINE\HARDWARE\DESCRIPTION\System\CentralProcessor

    private void determineNumberOfProcessCores()
    {
        RegistryKey rk = Registry.LocalMachine;
        String[] subKeys = rk.OpenSubKey("HARDWARE").OpenSubKey("DESCRIPTION").OpenSubKey("System").OpenSubKey("CentralProcessor").GetSubKeyNames();

        textBox1.Text = "Total number of cores:" + subKeys.Length.ToString();
    }

我有理由确定大多数系统上都会有注册表项。

以为我会把我的 0.02 美元扔进去。

于 2014-06-04T06:16:48.823 回答
0

以下程序打印 Windows 机器的逻辑和物理内核。

#define STRICT
#include "stdafx.h"
#include <windows.h>
#include <stdio.h>
#include <omp.h>

template<typename T>
T *AdvanceBytes(T *p, SIZE_T cb)
{
 return reinterpret_cast<T*>(reinterpret_cast<BYTE *>(p) + cb);
}

class EnumLogicalProcessorInformation
{
public:
 EnumLogicalProcessorInformation(LOGICAL_PROCESSOR_RELATIONSHIP Relationship)
  : m_pinfoBase(nullptr), m_pinfoCurrent(nullptr), m_cbRemaining(0)
 {
  DWORD cb = 0;
  if (GetLogicalProcessorInformationEx(Relationship,
                                       nullptr, &cb)) return;
  if (GetLastError() != ERROR_INSUFFICIENT_BUFFER) return;

  m_pinfoBase =
   reinterpret_cast<SYSTEM_LOGICAL_PROCESSOR_INFORMATION_EX *>
                                     (LocalAlloc(LMEM_FIXED, cb));
  if (!m_pinfoBase) return;

  if (!GetLogicalProcessorInformationEx(Relationship, 
                                        m_pinfoBase, &cb)) return;

  m_pinfoCurrent = m_pinfoBase;
  m_cbRemaining = cb;
 }

 ~EnumLogicalProcessorInformation() { LocalFree(m_pinfoBase); }

 void MoveNext()
 {
  if (m_pinfoCurrent) {
   m_cbRemaining -= m_pinfoCurrent->Size;
   if (m_cbRemaining) {
    m_pinfoCurrent = AdvanceBytes(m_pinfoCurrent,
                                  m_pinfoCurrent->Size);
   } else {
    m_pinfoCurrent = nullptr;
   }
  }
 }

 SYSTEM_LOGICAL_PROCESSOR_INFORMATION_EX *Current()
                                         { return m_pinfoCurrent; }
private:
 SYSTEM_LOGICAL_PROCESSOR_INFORMATION_EX *m_pinfoBase;
 SYSTEM_LOGICAL_PROCESSOR_INFORMATION_EX *m_pinfoCurrent;
 DWORD m_cbRemaining;
};


int __cdecl main(int argc, char **argv)
{
  int numLogicalCore = 0;
  int numPhysicalCore = 0;

  for (EnumLogicalProcessorInformation enumInfo(RelationProcessorCore);
      auto pinfo = enumInfo.Current(); enumInfo.MoveNext()) 
  {
      int numThreadPerCore = (pinfo->Processor.Flags == LTP_PC_SMT) ? 2 : 1;
      // std::cout << "thread per core: "<< numThreadPerCore << std::endl;
      numLogicalCore += numThreadPerCore;
      numPhysicalCore += 1;
  }

  printf ("Number of physical core = %d , Number of Logical core = %d \n", numPhysicalCore, numLogicalCore );

 char c = getchar(); /* just to wait on to see the results in the command prompt */
 return 0;
}

/*
I tested with Intel Xeon four cores with hyper threading and here is the result
Number of physical core = 4 , Number of Logical core = 8
*/
于 2014-06-04T03:15:12.717 回答
0

你可以使用这个类：

public static class CpuCores
{
    private static int cores = 0;
    
    public static int Number
    { 
        get
        {
            if (cores > 0) return cores;

            RegistryKey key = Registry.LocalMachine.OpenSubKey(@"SYSTEM\CurrentControlSet\Control\Class\" +
                "{50127dc3-0f36-415e-a6cc-4cb3be910b65}");
            if (key == null)
            {
                cores = Environment.ProcessorCount;
                return cores;
            }
            string[] subkeys = key.GetSubKeyNames();
            key.Close();
            cores = 0;
            if (subkeys != null && subkeys.Length > 0) foreach (string s in subkeys)
            {
                if (s.Length != 4) continue;
                int n;
                if (int.TryParse(s, out n) && ++n > cores) cores = n;
            }
            if (cores <= 0) cores = Environment.ProcessorCount;
            return cores;
        } 
    }
}
于 2021-04-12T21:01:15.127 回答
-1

我一直在寻找同样的东西，但我不想安装任何 nuget 或 servicepack，所以我找到了这个解决方案，它非常简单直接，使用这个讨论，我认为运行 WMIC 命令会很容易并获得该值，这是 C# 代码。您只需要使用 System.Management 命名空间（并为流程等结合更多标准命名空间）。

string fileName = Path.Combine(Environment.SystemDirectory, "wbem", "wmic.exe");
string arguments = @"cpu get NumberOfCores";

Process process = new Process
{
    StartInfo =
    {
        FileName = fileName,
        Arguments = arguments,
        UseShellExecute = false,
        CreateNoWindow = true,
        RedirectStandardOutput = true,
        RedirectStandardError = true
    }
};

process.Start();

StreamReader output = process.StandardOutput;
Console.WriteLine(output.ReadToEnd());


process.WaitForExit();
int exitCode = process.ExitCode;
process.Close();
于 2015-02-03T00:03:53.620 回答