有没有一种通过 .NET/C# 方法来找出 CPU 核心数的方式?
备注:这是一个纯粹的代码问题,而不是一个“我应该使用多线程?”的问题! :-)
有几个与处理器相关的不同信息:
这些可能都不同;对于具有2个双核心超线程启用处理器的机器,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(在某些系统上,您可能需要安装一些热修复程序或服务包):
确保在项目中添加对System.Management.dll的引用 在.NET Core中,这可作为NuGet软件包提供(仅限于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"]);
}
被Windows排除的处理器:
你还可以使用 setupapi.dll 中的 Windows API 调用来发现已被 Windows 排除(例如通过引导设置)且无法使用上述方法检测到的处理器。下面的代码给出了存在的逻辑处理器总数(我尚未能够区分物理和逻辑处理器),包括那些被 Windows 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,
}
deviceCount
是从0开始计数的,所以核心数量应该像这样输出:Console.WriteLine("Number of cores: {0}", deviceCount + 1);
。 - Francis Litterio7
... - VladEnvironment.ProcessorCount
Environment.ProcessorCount
只返回32个。 - Allen Clark Copeland JrWMI查询速度较慢,因此请尽量只选择所需成员而不是使用Select *。
以下查询需要3.4秒:
foreach (var item in new System.Management.ManagementObjectSearcher("Select * from Win32_Processor").Get())
虽然这个只需要0.122秒:
foreach (var item in new System.Management.ManagementObjectSearcher("Select NumberOfCores from Win32_Processor").Get())
最简单的方法是 = Environment.ProcessorCount
来自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);
}
}
看到.NET内部是如何实现的确实很有趣...它的实现方式非常“简单”,如下:
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;
}
}
}
}
Environment.ProcessorCount
的值,并且仅由某些同步相关类internal
使用。如何获取Environment.ProcessorCount
的值才是有信息量的。此外,看起来您是从反编译器而不是源代码获取此代码。 - Lance U. Matthews你也可以通过在 Kernel32.dll
上使用PInvoke 来获取它。
以下代码基本上来自于 System.Web 源代码中的 SystemInfo.cs
,位于这里:
[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;
}
}
这里已经有很多答案了,但有些答案得到了大量的赞,但是是不正确的。
.NET Environment.ProcessorCount会返回错误的值,如果您的系统WMI配置不正确,可能会导致严重失败。
如果您想要一个可靠的方法来计算核心数,唯一的方法是使用Win32 API。
下面是一个C++代码片段:
#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;
}
既然这是一个.NET C#问题,这里是转换后的版本:
[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();
一种选择是从注册表中读取数据。 有关此主题的MSDN文章:http://msdn.microsoft.com/en-us/library/microsoft.win32.registry.localmachine(v=vs.71).aspx)
我相信处理器可以在此处找到,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();
}
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;
}
}
}
Environment.ProcessorCount
,那为什么不一开始就直接使用它呢? - Lance U. Matthews