我正在尝试使用RDTSC，但似乎我的方法可能是错误的，以获得核心速度：
#include "stdafx.h"
#include <windows.h>
#include <process.h>
#include <iostream>
using namespace std;
struct Core
{
int CoreNumber;
};
static void startMonitoringCoreSpeeds(void *param)
{
Core core = *((Core *)param);
SetThreadAffinityMask(GetCurrentThread(), 1 << core.CoreNumber);
while (true)
{
DWORD64 first = __rdtsc();
Sleep(1000);
DWORD64 second = __rdtsc();
cout << "Core " << core.CoreNumber << " has frequency " << ((second - first)*pow(10, -6)) << " MHz" << endl;
}
}
int GetNumberOfProcessorCores()
{
DWORD process, system;
if (GetProcessAffinityMask(GetCurrentProcess(), &process, &system))
{
int count = 0;
for (int i = 0; i < 32; i++)
{
if (system & (1 << i))
{
count++;
}
}
return count;
}
SYSTEM_INFO sysinfo;
GetSystemInfo(&sysinfo);
return sysinfo.dwNumberOfProcessors;
}
int _tmain(int argc, _TCHAR* argv[])
{
for (int i = 0; i < GetNumberOfProcessorCores(); i++)
{
Core *core = new Core {0};
core->CoreNumber = i;
_beginthread(startMonitoringCoreSpeeds, 0, core);
}
cin.get();
}
它总是打印3.3 GHz附近的值，这是错误的，因为像Turbo Boost这样的东西不时打开，我的内核肯定会跳到4.3 GHz。让我交叉引用这个想法背后的一些文章。
首先（http://users.utcluj.ro/~ancapop/labscs/SCS2.pdf）：＆＃34;处理器核心上的TSC未同步。因此，如果进程在此期间迁移，则无法确定 从一个核心执行到另一个核心，测量不会受到影响。为避免此问题，必须将测量过程的亲和力设置为仅一个核心，以防止进程迁移。＆＃34;这告诉我RDTSC应该使用我设置的关联掩码为我的线程每个核心返回一个不同的值，这很棒。
其次，请查看这篇文章（http://randomascii.wordpress.com/2011/07/29/rdtsc-in-the-age-of-sandybridge/）：＆＃34;如果您需要一个可以跨核心工作的一致计时器，并且可以用来衡量时间，那么这很好新闻。如果你想测量实际的CPU时钟周期，那你就不走运了。如果你想要在各种各样的CPU系列中保持一致性，那么它很难成为你。更新：“Intel系统编程指南”的第16.11节介绍了时间戳计数器的这种行为。粗略地说，在较旧的处理器上，时钟频率会发生变化，但在较新的处理器上，它仍然是均匀的。最后，Constant TSC说：“这是未来的建筑行为。＆＃34;好的，这告诉我RDTSC保持一致，这使我的上述结果有意义，因为我的CPU内核的额定标准是3.3 GHz ......
真正引起疑问的是，英特尔的Turbo Boost技术监控器和Piriform的Speccy和CPUID的CPU-Z等应用程序如何衡量处理器的时钟速度在进行涡轮增压时，实时？
答案 0 :(得分：4)
完整的解决方案如下。我已经调整了IOCTL sample driver on MSDN来做到这一点。注意，IOCTL样本是the only relative WDM sample skeleton driver I could find and also the closest thing I could find to a WDM template，因为WDK中开箱即用的大多数内核模式模板都是基于WDF的驱动程序（任何WDM驱动程序模板实际上都是空白的，绝对没有源代码），但是the only sample logic I've seen to do this input/output was through a WDM-based driver。此外，我一路上学到了一些有趣的事实：内核驱动程序不喜欢浮动算法，你不能使用“windows.h”，它真正限制你使用“ntddk.h”，一个特殊的内核模式头。这也意味着我无法在内核模式下进行所有计算，因为我无法在那里调用QueryPerformanceFrequency等函数，所以我必须得到时间戳之间的平均性能比，并将它们返回到用户模式进行某些计算（如果没有QueryPerformanceFrequency，你从CPU寄存器中获得的值（如QueryPerformanceCounter所使用的那样存储滴答函）是无用的，因为你不知道步长;也许有一个解决方法，但我选择使用均值，因为它非常好用） 。另外，根据一秒睡眠，我使用它的原因是因为否则你几乎在多个线程上旋转计算狗屎，这实际上会影响你的计算，因为你的频率会逐渐上升，每个核心不断检查来自QueryPerformanceCounter的结果（你在进行更多计算时驱动你的核心） - 不要注意 - 它是一个比率......所以delta时间并不重要，因为它的每次循环次数...... 你可以随时增加delta，它仍然应该给出相对于步长的相同比率。此外，这是我所能达到的极简主义。祝你好运比它更小或更短。此外，如果你想安装驱动程序，你have two options，除非你想从某个第三方购买代码签名证书，这两个都很糟糕，所以选择一个并吮吸它。让我们从驱动程序开始：
<强> driver.c ：
//
// Include files.
//
#include <ntddk.h> // various NT definitions
#include <string.h>
#include <intrin.h>
#include "driver.h"
#define NT_DEVICE_NAME L"\\Device\\KernelModeDriver"
#define DOS_DEVICE_NAME L"\\DosDevices\\KernelModeDriver"
#if DBG
#define DRIVER_PRINT(_x_) \
DbgPrint("KernelModeDriver.sys: ");\
DbgPrint _x_;
#else
#define DRIVER_PRINT(_x_)
#endif
//
// Device driver routine declarations.
//
DRIVER_INITIALIZE DriverEntry;
_Dispatch_type_(IRP_MJ_CREATE)
_Dispatch_type_(IRP_MJ_CLOSE)
DRIVER_DISPATCH DriverCreateClose;
_Dispatch_type_(IRP_MJ_DEVICE_CONTROL)
DRIVER_DISPATCH DriverDeviceControl;
DRIVER_UNLOAD DriverUnloadDriver;
VOID
PrintIrpInfo(
PIRP Irp
);
VOID
PrintChars(
_In_reads_(CountChars) PCHAR BufferAddress,
_In_ size_t CountChars
);
#ifdef ALLOC_PRAGMA
#pragma alloc_text( INIT, DriverEntry )
#pragma alloc_text( PAGE, DriverCreateClose)
#pragma alloc_text( PAGE, DriverDeviceControl)
#pragma alloc_text( PAGE, DriverUnloadDriver)
#pragma alloc_text( PAGE, PrintIrpInfo)
#pragma alloc_text( PAGE, PrintChars)
#endif // ALLOC_PRAGMA
NTSTATUS
DriverEntry(
_In_ PDRIVER_OBJECT DriverObject,
_In_ PUNICODE_STRING RegistryPath
)
/*++
Routine Description:
This routine is called by the Operating System to initialize the driver.
It creates the device object, fills in the dispatch entry points and
completes the initialization.
Arguments:
DriverObject - a pointer to the object that represents this device
driver.
RegistryPath - a pointer to our Services key in the registry.
Return Value:
STATUS_SUCCESS if initialized; an error otherwise.
--*/
{
NTSTATUS ntStatus;
UNICODE_STRING ntUnicodeString; // NT Device Name "\Device\KernelModeDriver"
UNICODE_STRING ntWin32NameString; // Win32 Name "\DosDevices\KernelModeDriver"
PDEVICE_OBJECT deviceObject = NULL; // ptr to device object
UNREFERENCED_PARAMETER(RegistryPath);
RtlInitUnicodeString( &ntUnicodeString, NT_DEVICE_NAME );
ntStatus = IoCreateDevice(
DriverObject, // Our Driver Object
0, // We don't use a device extension
&ntUnicodeString, // Device name "\Device\KernelModeDriver"
FILE_DEVICE_UNKNOWN, // Device type
FILE_DEVICE_SECURE_OPEN, // Device characteristics
FALSE, // Not an exclusive device
&deviceObject ); // Returned ptr to Device Object
if ( !NT_SUCCESS( ntStatus ) )
{
DRIVER_PRINT(("Couldn't create the device object\n"));
return ntStatus;
}
//
// Initialize the driver object with this driver's entry points.
//
DriverObject->MajorFunction[IRP_MJ_CREATE] = DriverCreateClose;
DriverObject->MajorFunction[IRP_MJ_CLOSE] = DriverCreateClose;
DriverObject->MajorFunction[IRP_MJ_DEVICE_CONTROL] = DriverDeviceControl;
DriverObject->DriverUnload = DriverUnloadDriver;
//
// Initialize a Unicode String containing the Win32 name
// for our device.
//
RtlInitUnicodeString( &ntWin32NameString, DOS_DEVICE_NAME );
//
// Create a symbolic link between our device name and the Win32 name
//
ntStatus = IoCreateSymbolicLink(
&ntWin32NameString, &ntUnicodeString );
if ( !NT_SUCCESS( ntStatus ) )
{
//
// Delete everything that this routine has allocated.
//
DRIVER_PRINT(("Couldn't create symbolic link\n"));
IoDeleteDevice( deviceObject );
}
return ntStatus;
}
NTSTATUS
DriverCreateClose(
PDEVICE_OBJECT DeviceObject,
PIRP Irp
)
/*++
Routine Description:
This routine is called by the I/O system when the KernelModeDriver is opened or
closed.
No action is performed other than completing the request successfully.
Arguments:
DeviceObject - a pointer to the object that represents the device
that I/O is to be done on.
Irp - a pointer to the I/O Request Packet for this request.
Return Value:
NT status code
--*/
{
UNREFERENCED_PARAMETER(DeviceObject);
PAGED_CODE();
Irp->IoStatus.Status = STATUS_SUCCESS;
Irp->IoStatus.Information = 0;
IoCompleteRequest( Irp, IO_NO_INCREMENT );
return STATUS_SUCCESS;
}
VOID
DriverUnloadDriver(
_In_ PDRIVER_OBJECT DriverObject
)
/*++
Routine Description:
This routine is called by the I/O system to unload the driver.
Any resources previously allocated must be freed.
Arguments:
DriverObject - a pointer to the object that represents our driver.
Return Value:
None
--*/
{
PDEVICE_OBJECT deviceObject = DriverObject->DeviceObject;
UNICODE_STRING uniWin32NameString;
PAGED_CODE();
//
// Create counted string version of our Win32 device name.
//
RtlInitUnicodeString( &uniWin32NameString, DOS_DEVICE_NAME );
//
// Delete the link from our device name to a name in the Win32 namespace.
//
IoDeleteSymbolicLink( &uniWin32NameString );
if ( deviceObject != NULL )
{
IoDeleteDevice( deviceObject );
}
}
NTSTATUS
DriverDeviceControl(
PDEVICE_OBJECT DeviceObject,
PIRP Irp
)
/*++
Routine Description:
This routine is called by the I/O system to perform a device I/O
control function.
Arguments:
DeviceObject - a pointer to the object that represents the device
that I/O is to be done on.
Irp - a pointer to the I/O Request Packet for this request.
Return Value:
NT status code
--*/
{
PIO_STACK_LOCATION irpSp;// Pointer to current stack location
NTSTATUS ntStatus = STATUS_SUCCESS;// Assume success
ULONG inBufLength; // Input buffer length
ULONG outBufLength; // Output buffer length
void *inBuf; // pointer to input buffer
unsigned __int64 *outBuf; // pointer to the output buffer
UNREFERENCED_PARAMETER(DeviceObject);
PAGED_CODE();
irpSp = IoGetCurrentIrpStackLocation( Irp );
inBufLength = irpSp->Parameters.DeviceIoControl.InputBufferLength;
outBufLength = irpSp->Parameters.DeviceIoControl.OutputBufferLength;
if (!inBufLength || !outBufLength || outBufLength != sizeof(unsigned __int64)*2)
{
ntStatus = STATUS_INVALID_PARAMETER;
goto End;
}
//
// Determine which I/O control code was specified.
//
switch ( irpSp->Parameters.DeviceIoControl.IoControlCode )
{
case IOCTL_SIOCTL_METHOD_BUFFERED:
//
// In this method the I/O manager allocates a buffer large enough to
// to accommodate larger of the user input buffer and output buffer,
// assigns the address to Irp->AssociatedIrp.SystemBuffer, and
// copies the content of the user input buffer into this SystemBuffer
//
DRIVER_PRINT(("Called IOCTL_SIOCTL_METHOD_BUFFERED\n"));
PrintIrpInfo(Irp);
//
// Input buffer and output buffer is same in this case, read the
// content of the buffer before writing to it
//
inBuf = (void *)Irp->AssociatedIrp.SystemBuffer;
outBuf = (unsigned __int64 *)Irp->AssociatedIrp.SystemBuffer;
//
// Read the data from the buffer
//
DRIVER_PRINT(("\tData from User :"));
//
// We are using the following function to print characters instead
// DebugPrint with %s format because we string we get may or
// may not be null terminated.
//
PrintChars(inBuf, inBufLength);
//
// Write to the buffer
//
unsigned __int64 data[sizeof(unsigned __int64) * 2];
data[0] = __readmsr(232);
data[1] = __readmsr(231);
DRIVER_PRINT(("data[0]: %d", data[0]));
DRIVER_PRINT(("data[1]: %d", data[1]));
RtlCopyBytes(outBuf, data, outBufLength);
//
// Assign the length of the data copied to IoStatus.Information
// of the Irp and complete the Irp.
//
Irp->IoStatus.Information = sizeof(unsigned __int64)*2;
//
// When the Irp is completed the content of the SystemBuffer
// is copied to the User output buffer and the SystemBuffer is
// is freed.
//
break;
default:
//
// The specified I/O control code is unrecognized by this driver.
//
ntStatus = STATUS_INVALID_DEVICE_REQUEST;
DRIVER_PRINT(("ERROR: unrecognized IOCTL %x\n",
irpSp->Parameters.DeviceIoControl.IoControlCode));
break;
}
End:
//
// Finish the I/O operation by simply completing the packet and returning
// the same status as in the packet itself.
//
Irp->IoStatus.Status = ntStatus;
IoCompleteRequest( Irp, IO_NO_INCREMENT );
return ntStatus;
}
VOID
PrintIrpInfo(
PIRP Irp)
{
PIO_STACK_LOCATION irpSp;
irpSp = IoGetCurrentIrpStackLocation( Irp );
PAGED_CODE();
DRIVER_PRINT(("\tIrp->AssociatedIrp.SystemBuffer = 0x%p\n",
Irp->AssociatedIrp.SystemBuffer));
DRIVER_PRINT(("\tIrp->UserBuffer = 0x%p\n", Irp->UserBuffer));
DRIVER_PRINT(("\tirpSp->Parameters.DeviceIoControl.Type3InputBuffer = 0x%p\n",
irpSp->Parameters.DeviceIoControl.Type3InputBuffer));
DRIVER_PRINT(("\tirpSp->Parameters.DeviceIoControl.InputBufferLength = %d\n",
irpSp->Parameters.DeviceIoControl.InputBufferLength));
DRIVER_PRINT(("\tirpSp->Parameters.DeviceIoControl.OutputBufferLength = %d\n",
irpSp->Parameters.DeviceIoControl.OutputBufferLength ));
return;
}
VOID
PrintChars(
_In_reads_(CountChars) PCHAR BufferAddress,
_In_ size_t CountChars
)
{
PAGED_CODE();
if (CountChars) {
while (CountChars--) {
if (*BufferAddress > 31
&& *BufferAddress != 127) {
KdPrint (( "%c", *BufferAddress) );
} else {
KdPrint(( ".") );
}
BufferAddress++;
}
KdPrint (("\n"));
}
return;
}
<强> driver.h ：
//
// Device type -- in the "User Defined" range."
//
#define SIOCTL_TYPE 40000
//
// The IOCTL function codes from 0x800 to 0xFFF are for customer use.
//
#define IOCTL_SIOCTL_METHOD_IN_DIRECT \
CTL_CODE( SIOCTL_TYPE, 0x900, METHOD_IN_DIRECT, FILE_ANY_ACCESS )
#define IOCTL_SIOCTL_METHOD_OUT_DIRECT \
CTL_CODE( SIOCTL_TYPE, 0x901, METHOD_OUT_DIRECT , FILE_ANY_ACCESS )
#define IOCTL_SIOCTL_METHOD_BUFFERED \
CTL_CODE( SIOCTL_TYPE, 0x902, METHOD_BUFFERED, FILE_ANY_ACCESS )
#define IOCTL_SIOCTL_METHOD_NEITHER \
CTL_CODE( SIOCTL_TYPE, 0x903, METHOD_NEITHER , FILE_ANY_ACCESS )
#define DRIVER_FUNC_INSTALL 0x01
#define DRIVER_FUNC_REMOVE 0x02
#define DRIVER_NAME "ReadMSRDriver"
现在，这是加载并使用驱动程序的应用程序（Win32控制台应用程序）：
<强> FrequencyCalculator.cpp ：
#include "stdafx.h"
#include <iostream>
#include <windows.h>
#include <winioctl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <strsafe.h>
#include <process.h>
#include "..\KernelModeDriver\driver.h"
using namespace std;
BOOLEAN
ManageDriver(
_In_ LPCTSTR DriverName,
_In_ LPCTSTR ServiceName,
_In_ USHORT Function
);
HANDLE hDevice;
TCHAR driverLocation[MAX_PATH];
void InstallDriver()
{
DWORD errNum = 0;
GetCurrentDirectory(MAX_PATH, driverLocation);
_tcscat_s(driverLocation, _T("\\KernelModeDriver.sys"));
std::wcout << "Trying to install driver at " << driverLocation << std::endl;
//
// open the device
//
if ((hDevice = CreateFile(_T("\\\\.\\KernelModeDriver"),
GENERIC_READ | GENERIC_WRITE,
0,
NULL,
CREATE_ALWAYS,
FILE_ATTRIBUTE_NORMAL,
NULL)) == INVALID_HANDLE_VALUE) {
errNum = GetLastError();
if (errNum != ERROR_FILE_NOT_FOUND) {
printf("CreateFile failed! ERROR_FILE_NOT_FOUND = %d\n", errNum);
return;
}
//
// The driver is not started yet so let us the install the driver.
// First setup full path to driver name.
//
if (!ManageDriver(_T(DRIVER_NAME),
driverLocation,
DRIVER_FUNC_INSTALL
)) {
printf("Unable to install driver. \n");
//
// Error - remove driver.
//
ManageDriver(_T(DRIVER_NAME),
driverLocation,
DRIVER_FUNC_REMOVE
);
return;
}
hDevice = CreateFile(_T("\\\\.\\KernelModeDriver"),
GENERIC_READ | GENERIC_WRITE,
0,
NULL,
CREATE_ALWAYS,
FILE_ATTRIBUTE_NORMAL,
NULL);
if (hDevice == INVALID_HANDLE_VALUE){
printf("Error: CreatFile Failed : %d\n", GetLastError());
return;
}
}
}
void UninstallDriver()
{
//
// close the handle to the device.
//
CloseHandle(hDevice);
//
// Unload the driver. Ignore any errors.
//
ManageDriver(_T(DRIVER_NAME),
driverLocation,
DRIVER_FUNC_REMOVE
);
}
double GetPerformanceRatio()
{
BOOL bRc;
ULONG bytesReturned;
int input = 0;
unsigned __int64 output[2];
memset(output, 0, sizeof(unsigned __int64) * 2);
//printf("InputBuffer Pointer = %p, BufLength = %d\n", &input, sizeof(&input));
//printf("OutputBuffer Pointer = %p BufLength = %d\n", &output, sizeof(&output));
//
// Performing METHOD_BUFFERED
//
//printf("\nCalling DeviceIoControl METHOD_BUFFERED:\n");
bRc = DeviceIoControl(hDevice,
(DWORD)IOCTL_SIOCTL_METHOD_BUFFERED,
&input,
sizeof(&input),
output,
sizeof(unsigned __int64)*2,
&bytesReturned,
NULL
);
if (!bRc)
{
//printf("Error in DeviceIoControl : %d", GetLastError());
return 0;
}
//printf(" OutBuffer (%d): %d\n", bytesReturned, output);
if (output[1] == 0)
{
return 0;
}
else
{
return (float)output[0] / (float)output[1];
}
}
struct Core
{
int CoreNumber;
};
int GetNumberOfProcessorCores()
{
SYSTEM_INFO sysinfo;
GetSystemInfo(&sysinfo);
return sysinfo.dwNumberOfProcessors;
}
float GetCoreFrequency()
{
// __rdtsc: Returns the processor time stamp which records the number of clock cycles since the last reset.
// QueryPerformanceCounter: Returns a high resolution time stamp that can be used for time-interval measurements.
// Get the frequency which defines the step size of the QueryPerformanceCounter method.
LARGE_INTEGER frequency;
QueryPerformanceFrequency(&frequency);
// Get the number of cycles before we start.
ULONG cyclesBefore = __rdtsc();
// Get the Intel performance ratio at the start.
float ratioBefore = GetPerformanceRatio();
// Get the start time.
LARGE_INTEGER startTime;
QueryPerformanceCounter(&startTime);
// Give the CPU cores enough time to repopulate their __rdtsc and QueryPerformanceCounter registers.
Sleep(1000);
ULONG cyclesAfter = __rdtsc();
// Get the Intel performance ratio at the end.
float ratioAfter = GetPerformanceRatio();
// Get the end time.
LARGE_INTEGER endTime;
QueryPerformanceCounter(&endTime);
// Return the number of MHz. Multiply the core's frequency by the mean MSR (model-specific register) ratio (the APERF register's value divided by the MPERF register's value) between the two timestamps.
return ((ratioAfter + ratioBefore) / 2)*(cyclesAfter - cyclesBefore)*pow(10, -6) / ((endTime.QuadPart - startTime.QuadPart) / frequency.QuadPart);
}
struct CoreResults
{
int CoreNumber;
float CoreFrequency;
};
CRITICAL_SECTION printLock;
static void printResult(void *param)
{
EnterCriticalSection(&printLock);
CoreResults coreResults = *((CoreResults *)param);
std::cout << "Core " << coreResults.CoreNumber << " has a speed of " << coreResults.CoreFrequency << " MHz" << std::endl;
delete param;
LeaveCriticalSection(&printLock);
}
bool closed = false;
static void startMonitoringCoreSpeeds(void *param)
{
Core core = *((Core *)param);
SetThreadAffinityMask(GetCurrentThread(), 1 << core.CoreNumber);
while (!closed)
{
CoreResults *coreResults = new CoreResults();
coreResults->CoreNumber = core.CoreNumber;
coreResults->CoreFrequency = GetCoreFrequency();
_beginthread(printResult, 0, coreResults);
Sleep(1000);
}
delete param;
}
int _tmain(int argc, _TCHAR* argv[])
{
InitializeCriticalSection(&printLock);
InstallDriver();
for (int i = 0; i < GetNumberOfProcessorCores(); i++)
{
Core *core = new Core{ 0 };
core->CoreNumber = i;
_beginthread(startMonitoringCoreSpeeds, 0, core);
}
std::cin.get();
closed = true;
UninstallDriver();
DeleteCriticalSection(&printLock);
}
它使用install.cpp，您可以从IOCTL示例中获取。如果不是今晚，我将在接下来的几天内在my blog发布一个有效的，完全正常的解决方案（明显包含代码）。
修改：在http://www.dima.to/blog/?p=101发布博客（此处提供完整源代码）...