题
有没有办法通过 .NET/C# 找出CPU核心数?
PS 这是一个直接的代码问题,而不是“我应该使用多线程吗?:-)
解决方案
有几种不同碎片有关的信息处理器可能获得:
- 许多物理处理器
- 核心数
- 逻辑处理器数目。
这些都可以有所不同;在机械的情况下有2个双核超线程的启用处理器,有2个物理处理器、核4和8的逻辑处理器。
逻辑处理器的数量可通过 环境 类,但其他信息是只能通过 WMI (你可能需要安装一些 修补程序或服务包 得到它在一些系统):
确保添加一个参考你的项目System.Management.dll
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"]);
}
芯:
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
foreach (var item in new System.Management.ManagementObjectSearcher("Select * from Win32_ComputerSystem").Get())
{
Console.WriteLine("Number Of Logical Processors: {0}", item["NumberOfLogicalProcessors"]);
}
处理器排除从窗口:
你也可以使用的Windows API电话在 setupapi.dll 发现处理已经排除从窗户(例如通过启动设置的)和不可探测的使用上述手段。代码下面给出总数的逻辑处理器(我还没有能够找出如何区分物理从逻辑处理器),存在,包括那些已经被排除从窗口:
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 - 1;
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,
}
其他提示
Environment.ProcessorCount
WMI查询很慢,所以尽量只选择,而不是使用选择*所需的成员。
下面的查询需要3.4s:
foreach (var item in new System.Management.ManagementObjectSearcher("Select * from Win32_Processor").Get())
虽然这一个需要0.122s:
foreach (var item in new System.Management.ManagementObjectSearcher("Select NumberOfCores from Win32_Processor").Get())
Environment.ProcessorCount 应该给你多少的本地机器上的核。
这是相当有趣的,看看.NET如何得到这个内部,至少可以说...这是“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;
}
}
}
}
最简单的方法= Environment.ProcessorCount
示例来自 Environment.ProcessorCount 属性
using System;
class Sample
{
public static void Main()
{
Console.WriteLine("The number of processors " +
"on this computer is {0}.",
Environment.ProcessorCount);
}
}
来自 .NET Framework 源代码
你也可以通过 调用 在 Kernel32.dll
以下代码或多或少来自 SystemInfo.cs
来自 System.Web 源代码 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;
}
}
一种选择是从注册表中读取数据。有关该主题的 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();
}
我有理由确信大多数系统上都会有该注册表项。
不过我会投入 0.02 美元。
下面的程序将打印的Windows机器的逻辑和物理核。
#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
*/
我一直在寻找同样的事情,但我不想安装任何的NuGet或服务包,所以我发现这个解决方案,它是非常简单和直接的, 使用这个的讨论,我想它会这么容易运行WMIC命令和获取价值,这里是C#代码。你只需要使用System.Management命名空间(和夫妇更标准的命名空间处理等)。
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();