有没有办法通过。net / c#找到CPU核数?
PS:这是一个直接的代码问题，不是一个“我应该使用多线程吗?”的问题!: -)
当前回答
这里已经有很多答案了，但有些得到了很高的赞，有些是不正确的。
. net环境。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。
如果你想要一个可靠的方法来计算内核，唯一的方法是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;
}
由于这是一个。net c#问题，下面是移植版本:
[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();
其他回答
WMI查询很慢，所以尽量只选择所需的成员，而不是使用Select *。
查询时间为3.4s:
foreach (var item in new System.Management.ManagementObjectSearcher("Select * from Win32_Processor").Get())
而这个需要0.122秒:
foreach (var item in new System.Management.ManagementObjectSearcher("Select NumberOfCores from Win32_Processor").Get())
Environment.ProcessorCount
(文档)
这里已经有很多答案了，但有些得到了很高的赞，有些是不正确的。
. net环境。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。
如果你想要一个可靠的方法来计算内核，唯一的方法是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;
}
由于这是一个。net c#问题，下面是移植版本:
[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();
最简单的方法=环境。ProcessorCount 例子来自环境。ProcessorCount财产
using System;
class Sample
{
public static void Main()
{
Console.WriteLine("The number of processors " +
"on this computer is {0}.",
Environment.ProcessorCount);
}
}
看看。net是如何在内部做到这一点的，至少可以说是相当有趣的……如下图所示:
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;
}
}
}
}
