现在多核处理器已经很普及了，市场主流是双核处理器，还有4核、8核等高端产品。而且Intel推广了超线程技术（Hyper-Threading Technology, HTT），可以将一个物理核心模拟为两个逻辑处理器。这一切使得“CPU数量”这一概念变得复杂起来，对于软件开发人员来说，希望能获得物理CPU数、CPU核心数、逻辑CPU数等详细信息。
在Windows平台，可以调用GetLogicalProcessorInformation函数来获取它们的详细信息。
一、背景知识
先来明确一下名词——
physical processor packages：物理处理器封装个数，即俗称的“物理CPU数”。例如一块“Intel Core i3-2310M”只有1个“物理处理器封装个数”。若对于有多个处理器插槽的服务器，“物理处理器封装个数”很可能会大于1。
processor cores：处理器核心数，即俗称的“CPU核心数”。例如“Intel Core i3-2310M”是双核处理器，它有2个“处理器核心数”。
logical processors：逻辑处理器数，即俗称的“逻辑CPU数”。例如“Intel Core i3-2310M”支持超线程，一个物理核心能模拟为两个逻辑处理器，即一块“Intel Core i3-2310M”有4个“逻辑处理器数”。
再来看看2个大家可能不太熟悉的名词——
SMP：Symmetrical Multi-Processing，对称多处理机。
NUMA：Non Uniform Memory Access，非均匀访存模型。http://msdn.microsoft.com/en-us/library/aa363804(v=vs.85).aspx
这个两个名词牵涉到很多专业知识，这里不做详细介绍，感兴趣的同学可以自行翻阅相关资料。
老版本的Windows系统（例如Windows XP）采用的是SMP模型。但后来因多核处理器及异构计算的发展，从Windows Server 2003开始使用NUMA模型，系统中支持多个NUMA节点。对于开发人员来说，当只有1个NUMA节点时，与SMP模型是差不多的。
对于 Windows XP，在打上SP3补丁后，也可以利用GetLogicalProcessorInformation函数获得NUMA等信息。
二、GetLogicalProcessorInformation函数的使用心得
在MSDN上我们可以查到GetLogicalProcessorInformation函数的帮助——
http://msdn.microsoft.com/en-us/library/ms683194(v=vs.85).aspxGetLogicalProcessorInformation function
GetLogicalProcessorInformation函数还牵涉到一些结构体和枚举——
http://msdn.microsoft.com/en-us/library/ms686694(v=vs.85).aspxSYSTEM_LOGICAL_PROCESSOR_INFORMATION structure
http://msdn.microsoft.com/en-us/library/ms684197(v=vs.85).aspxLOGICAL_PROCESSOR_RELATIONSHIP enumeration
http://msdn.microsoft.com/en-us/library/ms681979(v=vs.85).aspxCACHE_DESCRIPTOR structure
http://msdn.microsoft.com/en-us/library/ms684844(v=vs.85).aspxPROCESSOR_CACHE_TYPE enumeration
GetLogicalProcessorInformation函数用起来是有一定复杂性的。因为它返回的是SYSTEM_LOGICAL_PROCESSOR_INFORMATION数组，数组中的每一项分别描述了不同的信息，学习曲线较陡峭。
虽然MSDN上有该函数的范例代码，但是它屏蔽了很多细节，对我们的帮助有限。于是我将该范例程序作了改进，显示了SYSTEM_LOGICAL_PROCESSOR_INFORMATION数组中每一项的详细信息。
心得——
1.SYSTEM_LOGICAL_PROCESSOR_INFORMATION结构ProcessorMask是ULONG_PTR类型的。在32位系统上是32位，64位系统上是64位。为了简化代码，建议强制转型为UINT64类型，调用printf等输出函数时使用“I64”格式码。
2.ProcessorMask是处理器掩码，每一位代表一个逻辑处理器。所以一般来说，32位系统最多支持32个逻辑处理器，64位系统最多支持64个逻辑处理器。
3.对于Windows 7和Windows Server 2008 R2来说，能突破64个逻辑处理器限制，最高支持256个逻辑处理器。新加了 处理器组（Processor Groups）概念，详见：http://msdn.microsoft.com/en-us/library/dd405503(v=vs.85).aspx。
三、全部代码
全部代码——
#include <windows.h>
#include <malloc.h>
#include <stdio.h>
#include <tchar.h>
#if (_WIN32_WINNT < 0x0600) // [zyl910] 低版本的Windows SDK没有定义 RelationProcessorPackage 等常量
#define RelationProcessorPackage 3
#define RelationGroup 4
#endif
// [zyl910] LOGICAL_PROCESSOR_RELATIONSHIP枚举的名称
const LPTSTR Names_LOGICAL_PROCESSOR_RELATIONSHIP[] = {
_T("RelationProcessorCore")
,_T("RelationNumaNode")
,_T("RelationCache")
,_T("RelationProcessorPackage")
,_T("RelationGroup")
};
// [zyl910] PROCESSOR_CACHE_TYPE枚举的名称
const LPTSTR Names_PROCESSOR_CACHE_TYPE[] = {
_T("CacheUnified")
,_T("CacheInstruction")
,_T("CacheData")
,_T("CacheTrace")
};
typedef BOOL (WINAPI *LPFN_GLPI)(
PSYSTEM_LOGICAL_PROCESSOR_INFORMATION,
PDWORD);
// Helper function to count set bits in the processor mask.
DWORD CountSetBits(ULONG_PTR bitMask)
{
DWORD LSHIFT = sizeof(ULONG_PTR)*8 - 1;
DWORD bitSetCount = 0;
ULONG_PTR bitTest = (ULONG_PTR)1 << LSHIFT;
DWORD i;
for (i = 0; i <= LSHIFT; ++i)
{
bitSetCount += ((bitMask & bitTest)?1:0);
bitTest/=2;
}
return bitSetCount;
}
int _cdecl _tmain ()
{
LPFN_GLPI glpi;
BOOL done = FALSE;
PSYSTEM_LOGICAL_PROCESSOR_INFORMATION buffer = NULL;
PSYSTEM_LOGICAL_PROCESSOR_INFORMATION ptr = NULL;
DWORD returnLength = 0;
DWORD logicalProcessorCount = 0;
DWORD numaNodeCount = 0;
DWORD processorCoreCount = 0;
DWORD processorL1CacheCount = 0;
DWORD processorL2CacheCount = 0;
DWORD processorL3CacheCount = 0;
DWORD processorPackageCount = 0;
DWORD byteOffset = 0;
PCACHE_DESCRIPTOR Cache;
glpi = (LPFN_GLPI) GetProcAddress(
GetModuleHandle(TEXT("kernel32")),
"GetLogicalProcessorInformation");
if (NULL == glpi)
{
_tprintf(TEXT("\nGetLogicalProcessorInformation is not supported.\n"));
return (1);
}
while (!done)
{
DWORD rc = glpi(buffer, &returnLength);
if (FALSE == rc)
{
if (GetLastError() == ERROR_INSUFFICIENT_BUFFER)
{
if (buffer)
free(buffer);
buffer = (PSYSTEM_LOGICAL_PROCESSOR_INFORMATION)malloc(
returnLength);
if (NULL == buffer)
{
_tprintf(TEXT("\nError: Allocation failure\n"));
return (2);
}
}
else
{
_tprintf(TEXT("\nError %d\n"), GetLastError());
return (3);
}
}
else
{
done = TRUE;
}
}
ptr = buffer;
if (true) // [zyl910] 显示SYSTEM_LOGICAL_PROCESSOR_INFORMATION结构体的详细信息
{
DWORD cnt = returnLength / sizeof(SYSTEM_LOGICAL_PROCESSOR_INFORMATION); // 计算SYSTEM_LOGICAL_PROCESSOR_INFORMATION结构体的数目
for(DWORD i=0; i<cnt; ++i)
{
_tprintf(TEXT("SYSTEM_LOGICAL_PROCESSOR_INFORMATION[%d]\n"), i);
_tprintf(TEXT("\t.ProcessorMask:\t0x%.16I64X\t//%I64d\n"), (UINT64)ptr[i].ProcessorMask, (UINT64)ptr[i].ProcessorMask);
_tprintf(TEXT("\t.Relationship:\t%d\t//%s\n"), ptr[i].Relationship, Names_LOGICAL_PROCESSOR_RELATIONSHIP[max(0,min(ptr[i].Relationship, RelationGroup))]);
for(int j=0; j<2; ++j) _tprintf(TEXT("\t.Reserved[%d]:\t//0x%.16I64X\t%I64d\n"), j, (UINT64)ptr[i].Reserved[j], (UINT64)ptr[i].Reserved[j]);
if (RelationCache==ptr[i].Relationship)
{
_tprintf(TEXT("\t.Cache.Level:\t%u\n"), ptr[i].Cache.Level);
_tprintf(TEXT("\t.Cache.Associativity:\t0x%.2X\t//%u\n"), ptr[i].Cache.Associativity, ptr[i].Cache.Associativity);
_tprintf(TEXT("\t.Cache.LineSize:\t0x%.4X\t//%u\n"), ptr[i].Cache.LineSize, ptr[i].Cache.LineSize);
_tprintf(TEXT("\t.Cache.Size:\t0x%.8X\t//%u\n"), ptr[i].Cache.Size, ptr[i].Cache.Size);
_tprintf(TEXT("\t.Cache.Type:\t%d\t//%s\n"), ptr[i].Cache.Type, Names_PROCESSOR_CACHE_TYPE[max(0,min(ptr[i].Cache.Type, CacheTrace))]);
}
}
}
while (byteOffset + sizeof(SYSTEM_LOGICAL_PROCESSOR_INFORMATION) <= returnLength)
{
switch (ptr->Relationship)
{
case RelationNumaNode:
// Non-NUMA systems report a single record of this type.
numaNodeCount++;
break;
case RelationProcessorCore:
processorCoreCount++;
// A hyperthreaded core supplies more than one logical processor.
logicalProcessorCount += CountSetBits(ptr->ProcessorMask);
break;
case RelationCache:
// Cache data is in ptr->Cache, one CACHE_DESCRIPTOR structure for each cache.
Cache = &ptr->Cache;
if (Cache->Level == 1)
{
processorL1CacheCount++;
}
else if (Cache->Level == 2)
{
processorL2CacheCount++;
}
else if (Cache->Level == 3)
{
processorL3CacheCount++;
}
break;
case RelationProcessorPackage:
// Logical processors share a physical package.
processorPackageCount++;
break;
default:
_tprintf(TEXT("\nError: Unsupported LOGICAL_PROCESSOR_RELATIONSHIP value.\n"));
break;
}
byteOffset += sizeof(SYSTEM_LOGICAL_PROCESSOR_INFORMATION);
ptr++;
}
_tprintf(TEXT("\nGetLogicalProcessorInformation results:\n"));
_tprintf(TEXT("Number of NUMA nodes: %d\n"),
numaNodeCount);
_tprintf(TEXT("Number of physical processor packages: %d\n"),
processorPackageCount);
_tprintf(TEXT("Number of processor cores: %d\n"),
processorCoreCount);
_tprintf(TEXT("Number of logical processors: %d\n"),
logicalProcessorCount);
_tprintf(TEXT("Number of processor L1/L2/L3 caches: %d/%d/%d\n"),
processorL1CacheCount,
processorL2CacheCount,
processorL3CacheCount);
free(buffer);
return 0;
}
四、输出信息
例如我的处理器是“Intel Core i3-2310M”，该程序的输出信息为——
SYSTEM_LOGICAL_PROCESSOR_INFORMATION[0]
.ProcessorMask: 0x0000000000000005 //5
.Relationship: 0 //RelationProcessorCore
.Reserved[0]: //0x0000000000000001 1
.Reserved[1]: //0x0000000000000000 0
SYSTEM_LOGICAL_PROCESSOR_INFORMATION[1]
.ProcessorMask: 0x0000000000000005 //5
.Relationship: 2 //RelationCache
.Reserved[0]: //0x0000800000400801 140737492551681
.Reserved[1]: //0x0000000000000002 2
.Cache.Level: 1
.Cache.Associativity: 0x08 //8
.Cache.LineSize: 0x0040 //64
.Cache.Size: 0x00008000 //32768
.Cache.Type: 2 //CacheData
SYSTEM_LOGICAL_PROCESSOR_INFORMATION[2]
.ProcessorMask: 0x0000000000000005 //5
.Relationship: 2 //RelationCache
.Reserved[0]: //0x0000800000400801 140737492551681
.Reserved[1]: //0x0000000000000001 1
.Cache.Level: 1
.Cache.Associativity: 0x08 //8
.Cache.LineSize: 0x0040 //64
.Cache.Size: 0x00008000 //32768
.Cache.Type: 1 //CacheInstruction
SYSTEM_LOGICAL_PROCESSOR_INFORMATION[3]
.ProcessorMask: 0x0000000000000005 //5
.Relationship: 2 //RelationCache
.Reserved[0]: //0x0004000000400802 1125899911038978
.Reserved[1]: //0x0000000000000000 0
.Cache.Level: 2
.Cache.Associativity: 0x08 //8
.Cache.LineSize: 0x0040 //64
.Cache.Size: 0x00040000 //262144
.Cache.Type: 0 //CacheUnified
SYSTEM_LOGICAL_PROCESSOR_INFORMATION[4]
.ProcessorMask: 0x000000000000000F //15
.Relationship: 3 //RelationProcessorPackage
.Reserved[0]: //0x0000000000000000 0
.Reserved[1]: //0x0000000000000000 0
SYSTEM_LOGICAL_PROCESSOR_INFORMATION[5]
.ProcessorMask: 0x000000000000000A //10
.Relationship: 0 //RelationProcessorCore
.Reserved[0]: //0x0000000000000001 1
.Reserved[1]: //0x0000000000000000 0
SYSTEM_LOGICAL_PROCESSOR_INFORMATION[6]
.ProcessorMask: 0x000000000000000A //10
.Relationship: 2 //RelationCache
.Reserved[0]: //0x0000800000400801 140737492551681
.Reserved[1]: //0x0000000000000002 2
.Cache.Level: 1
.Cache.Associativity: 0x08 //8
.Cache.LineSize: 0x0040 //64
.Cache.Size: 0x00008000 //32768
.Cache.Type: 2 //CacheData
SYSTEM_LOGICAL_PROCESSOR_INFORMATION[7]
.ProcessorMask: 0x000000000000000A //10
.Relationship: 2 //RelationCache
.Reserved[0]: //0x0000800000400801 140737492551681
.Reserved[1]: //0x0000000000000001 1
.Cache.Level: 1
.Cache.Associativity: 0x08 //8
.Cache.LineSize: 0x0040 //64
.Cache.Size: 0x00008000 //32768
.Cache.Type: 1 //CacheInstruction
SYSTEM_LOGICAL_PROCESSOR_INFORMATION[8]
.ProcessorMask: 0x000000000000000A //10
.Relationship: 2 //RelationCache
.Reserved[0]: //0x0004000000400802 1125899911038978
.Reserved[1]: //0x0000000000000000 0
.Cache.Level: 2
.Cache.Associativity: 0x08 //8
.Cache.LineSize: 0x0040 //64
.Cache.Size: 0x00040000 //262144
.Cache.Type: 0 //CacheUnified
SYSTEM_LOGICAL_PROCESSOR_INFORMATION[9]
.ProcessorMask: 0x000000000000000F //15
.Relationship: 2 //RelationCache
.Reserved[0]: //0x0030000000400C03 13510798886308867
.Reserved[1]: //0x0000000000000000 0
.Cache.Level: 3
.Cache.Associativity: 0x0C //12
.Cache.LineSize: 0x0040 //64
.Cache.Size: 0x00300000 //3145728
.Cache.Type: 0 //CacheUnified
SYSTEM_LOGICAL_PROCESSOR_INFORMATION[10]
.ProcessorMask: 0x000000000000000F //15
.Relationship: 1 //RelationNumaNode
.Reserved[0]: //0x0000000000000000 0
.Reserved[1]: //0x0000000000000000 0
GetLogicalProcessorInformation results:
Number of NUMA nodes: 1
Number of physical processor packages: 1
Number of processor cores: 2
Number of logical processors: 4
Number of processor L1/L2/L3 caches: 4/2/1
