Get CPU Usage with GetSystemTimes

ejor

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20 Dec 2004Public Domain1 min read

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How to get CPU usage with GetSystemTimes

In this article, you will find a solution for getting CPU usage with the help of GetSystemTimes.

Download source files - 25.4 KB

Introduction

Since a very long time, a lot of people wanted to get the CPU usage from the computer.

You've a lot of ways to do this like calling registry like key or PerfCounter. But TaskManager doesn't call any of these ... If you're looking from the import table of TaskManager, you can find:

ntdll.dll
  Import Adress Table: 0x00001414
  Import Name Table: 0x00013C2C
      0x7C90E213 260 NtQueryVirtualMemory
      0x7C90DDF9 209 NtOpenThread
      0x7C90D586 103 NtClose
      ....
      0x7C90E1AA 255 NtQuerySystemInformation
      ....

So there is no other solution to have this information to dig into undocumented NtQuerySystemInformation. With this nice warning at the beginning of the article: [NtQuerySystemInformation is available for use in Windows 2000 and Windows XP. It may be altered or unavailable in subsequent versions. Applications should use the alternate functions listed in this topic.]

No other solution?

Well, GetSystemTimes is a good function if you have the requirements:

Client         Requires Windows XP SP1. 
Server         Requires Windows Server 2003. 
Header         Declared in Winbase.h; include Windows.h.
Library        Link to Kernel32.lib.
DLL            Requires Kernel32.dll.

How to Use It?

Call this:

FILETIME idleTime;
FILETIME kernelTime;
FILETIME userTime;
BOOL res = GetSystemTimes( &idleTime, &kernelTime, &userTime );

and voilà, you have almost what you need.

Now you have to poll this function and make a little calculus.

usr = userTime - last_userTime;
ker = kernelTime - last_kernelTime;
idl = idleTime - last_idleTime;

System time is:

sys = kerl + usr

idleTime is the rest because "System Idle" process is taking 100 % of CPU.

So CPU is:

cpu = int( (sys - idl) *100 / sys );

Conclusion

It was a very long wait before Microsoft gave us this function. Now it's done but there is still one problem. For multiple processor system, you don't have the right information.

In the sample, you can find the use of GetSystemTimes and GetProcessTimes and a little class to do everything.

class CPU
{
public:
  CPU( void );
  ~CPU( void );

  // return :
  // % of cpu usage for this process 
  // % cpu systemUsage 
  // uptime for this process
  int GetUsage( int* pSystemUsage, TKTime* pUpTime );

History

20^th December, 2004: Initial version

License

This article, along with any associated source code and files, is licensed under A Public Domain dedication

Written By

ejor

Web Developer

United Kingdom

http://dev.jesover.net

Comments and Discussions

bug fix

Member 18343684-Jun-16 17:30

Member 1834368

4-Jun-16 17:30

[CPU.cpp]
Line 052: 'if( s_hKernel == NULL )' should be 'if( s_hKernel )'
Line 191: in case 'sys == 0 || div == 0' you should return old values (fail)
Line 207~208: 's_index' incremented twice. suggested:

C++

s_cpu[s_index] = cpu;
s_cpuProcess[s_index] = cpuProcess;
s_index = (s_index + 1) % _countof(s_cpu);

and better to lock whole function if you don't need any atomic field update.

how to compile?

Mojtaba Setoodeh10-Sep-13 0:10

Mojtaba Setoodeh

10-Sep-13 0:10

what is the type and where have u defined last_userTime, last_kernelTime, last_idleTime, usr, ker, idl,sys in the code. sorry I couldn't compile the code. any help can be so useful. tnx

Re: how to compile?

ejor10-Sep-13 1:53

ejor

10-Sep-13 1:53

look in TKTime.h you've got the type definition

-----------------------------
ejor @ http://dev.jesover.net

Re: how to compile?

Mojtaba Setoodeh10-Sep-13 18:53

Mojtaba Setoodeh

10-Sep-13 18:53

hi buddy. there is no TKTime.h. i am using c++ in vs2012. shpuld i define in myself?

Re: how to compile?

ejor10-Sep-13 19:49

ejor

10-Sep-13 19:49

Huummmm how could say that.....
did you opened the zip an look at files ?

-----------------------------
ejor @ http://dev.jesover.net

Re: how to compile?

Mojtaba Setoodeh10-Sep-13 23:19

Mojtaba Setoodeh

10-Sep-13 23:19

tnx. i download the rar and i could run it. could u please tell me what is in the process and system variable? and how can i get total cpu usage in percent? i want to get when is system in ideal time(for example it is 10 min that cpu usage is less than 5 %). tnx a lot

When I use this function, I encountered an error that this function is undeclared, do you know why?

love_fairytale13-Mar-12 22:12

love_fairytale

13-Mar-12 22:12

Hey ejor:
I want to ask you a question.
When I use this function, I encountered an error that this function is undeclared.
I'm sure I have included the windows.h and according to the introduction of MSDN, defined the _WIN32_WINNT as 0x0501, but the error is still existent. Confused | :confused:

Can you give me some help to solve it?
Thank you very much~ Smile | :)

Re: When I use this function, I encountered an error that this function is undeclared, do you know why?

ejor20-Mar-12 3:13

ejor

20-Mar-12 3:13

remove
#define _WIN32_WINNT (0x0500)
in stdafx.h

-----------------------------
ejor @ http://dev.jesover.net

application usage

john56324-Mar-10 1:01

john5632

4-Mar-10 1:01

How to get cpu usage of specific application?

How to get CPU Usage for a particular process??

sanjibmail2-Jan-09 11:20

sanjibmail

2-Jan-09 11:20

Hi Ejor

Could you please let me know how to get the CPU Usage in % of a particular running process say 'taskmgr.exe'?

I would like to get the CPU Usage of a particular process running in PC.
Please help me. Cry | :((

Thanks
Sanjib

The way it's supposed to be...

Vitaly Tomilov2-Sep-08 5:53

Vitaly Tomilov

2-Sep-08 5:53

Here's the code that I got after throwing away about 90% of junk from your code.

This code allows getting CPU usage, and works not only on Windows XPSP1 or later, but also on Windows 2000/XP/2003/Vista/2008.

I did this to include CPU usage into ProSysLib as one of the CPU parameters.

Just two files, header + cpp.

ProcessorUsage.h:

C++

#pragma once


////////////////////////////////////////
// class CProcessorUsage;
//
// Calculates overal processor usage at
// any given time.
//
// The usage value is updated every 200
// milliseconds;
//
// The class is fully thread-safe;
//
class CProcessorUsage
{
	typedef BOOL (WINAPI * pfnGetSystemTimes)(LPFILETIME lpIdleTime, LPFILETIME lpKernelTime, LPFILETIME lpUserTime );
	typedef LONG (WINAPI * pfnNtQuerySystemInformation)(ULONG SystemInformationClass, PVOID SystemInformation, ULONG SystemInformationLength, PULONG ReturnLength);

	struct PROC_PERF_INFO
	{
		LARGE_INTEGER IdleTime;
		LARGE_INTEGER KernelTime;
		LARGE_INTEGER UserTime;
		LARGE_INTEGER Reserved1[2];
		ULONG Reserved2;
	};

public:

    CProcessorUsage();
    ~CProcessorUsage();

    USHORT GetUsage();

private:

	void GetSysTimes(__int64 & idleTime, __int64 & kernelTime, __int64 & userTime);

	////////////////////////////////////////////////
	// Set of static variables to be accessed from
	// within critical section by multiple threads:
	//
	static DWORD s_TickMark;
	static __int64 s_time;
	static __int64 s_idleTime;
	static __int64 s_kernelTime;
	static __int64 s_userTime;
	static int s_lastCpu;
	static int s_cpu[5];
	static __int64 s_kernelTimeProcess;
	static __int64 s_userTimeProcess;
	static int s_cpuProcess[5];
    static int s_count;
    static int s_index;
	//
	/////////////////////////////////////////////////

	pfnGetSystemTimes s_pfnGetSystemTimes;
	pfnNtQuerySystemInformation s_pfnNtQuerySystemInformation;
	CRITICAL_SECTION m_cs;
	PROC_PERF_INFO * m_pInfo;
	ULONG m_uInfoLength;
};

ProcessorUsage.cpp

C++

#include "StdAfx.h"
#include "ProcessorUsage.h"

DWORD CProcessorUsage::s_TickMark = 0;
__int64  CProcessorUsage::s_time = 0;
__int64 CProcessorUsage::s_idleTime = 0;
__int64 CProcessorUsage::s_kernelTime = 0;
__int64 CProcessorUsage::s_userTime = 0;
__int64 CProcessorUsage::s_kernelTimeProcess = 0;
__int64 CProcessorUsage::s_userTimeProcess = 0;
int CProcessorUsage::s_count = 0;
int CProcessorUsage::s_index = 0;
int CProcessorUsage::s_lastCpu = 0;
int CProcessorUsage::s_cpu[5] = {0, 0, 0, 0, 0};
int CProcessorUsage::s_cpuProcess[5] = {0, 0, 0, 0, 0};

CProcessorUsage::CProcessorUsage()
{
	::InitializeCriticalSection(&m_cs);

	s_pfnNtQuerySystemInformation = NULL;
	s_pfnGetSystemTimes = NULL;

	m_pInfo = NULL;
	m_uInfoLength = 0;

	HMODULE hModule  = ::GetModuleHandle(_T("kernel32.dll"));
	if(hModule)
		s_pfnGetSystemTimes = (pfnGetSystemTimes)::GetProcAddress(hModule, "GetSystemTimes");

	if(!s_pfnGetSystemTimes)
	{
		hModule = ::GetModuleHandle(_T("ntdll.dll"));
		if(hModule)
		{
			s_pfnNtQuerySystemInformation = (pfnNtQuerySystemInformation)::GetProcAddress(hModule, "NtQuerySystemInformation");
			if(s_pfnNtQuerySystemInformation)
			{
				s_pfnNtQuerySystemInformation(8, NULL, 0, &m_uInfoLength);
				m_pInfo = new PROC_PERF_INFO[m_uInfoLength / sizeof(PROC_PERF_INFO)];
			}
		}
	}
	s_TickMark = ::GetTickCount();
}

CProcessorUsage::~CProcessorUsage()
{
	if(m_pInfo)
		delete m_pInfo;

    ::DeleteCriticalSection(&m_cs);
}

void CProcessorUsage::GetSysTimes(__int64 & idleTime, __int64 & kernelTime, __int64 & userTime)
{
	if(s_pfnGetSystemTimes)
		s_pfnGetSystemTimes((LPFILETIME)&idleTime, (LPFILETIME)&kernelTime, (LPFILETIME)&userTime);
	else
	{
		idleTime = 0;
		kernelTime = 0;
		userTime = 0;
		if(s_pfnNtQuerySystemInformation && m_uInfoLength && !s_pfnNtQuerySystemInformation(0x08, m_pInfo, m_uInfoLength, &m_uInfoLength))
		{
			// NtQuerySystemInformation returns information for all
			// CPU cores in the system, so we take the average here:
			int nCores = m_uInfoLength / sizeof(PROC_PERF_INFO);
			for(int i = 0;i < nCores;i ++)
			{
				idleTime += m_pInfo[i].IdleTime.QuadPart;
				kernelTime += m_pInfo[i].KernelTime.QuadPart;
				userTime += m_pInfo[i].UserTime.QuadPart;
			}
			idleTime /= nCores;
			kernelTime /= nCores;
			userTime /= nCores;
		}
	}
}

USHORT CProcessorUsage::GetUsage()
{
    __int64 sTime;
    int sLastCpu;

	CCritSecLock cs(m_cs);
	sTime = s_time;
	sLastCpu = s_lastCpu;

    if(((::GetTickCount() - s_TickMark) & 0x7FFFFFFF) <= 200)
		return sLastCpu;

	__int64 time;
	__int64 idleTime;
	__int64 kernelTime;
	__int64 userTime;
	__int64 kernelTimeProcess;
	__int64 userTimeProcess;

	::GetSystemTimeAsFileTime((LPFILETIME)&time);

    if(!sTime)
    {
		GetSysTimes(idleTime, kernelTime, userTime);
		FILETIME createTime;
		FILETIME exitTime;
		::GetProcessTimes(::GetCurrentProcess(), &createTime, &exitTime, (LPFILETIME)&kernelTimeProcess, (LPFILETIME)&userTimeProcess);

		s_time = time;
		s_idleTime = idleTime;
		s_kernelTime = kernelTime;
		s_userTime = userTime;
		s_kernelTimeProcess = kernelTimeProcess;
		s_userTimeProcess = userTimeProcess;
		s_lastCpu = 0;
		s_TickMark = ::GetTickCount();
		return 0;
	}

    __int64 div = (time - sTime);

	GetSysTimes(idleTime, kernelTime, userTime);

	FILETIME createTime;
	FILETIME exitTime;
	::GetProcessTimes(::GetCurrentProcess(), &createTime, &exitTime, (LPFILETIME)&kernelTimeProcess, (LPFILETIME)&userTimeProcess);

    int cpu;
    int cpuProcess;

     __int64 usr = userTime   - s_userTime;
     __int64 ker = kernelTime - s_kernelTime;
     __int64 idl = idleTime   - s_idleTime;
     __int64 sys = (usr + ker);

	if(sys)
		cpu = int((sys - idl) * 100 / sys); // System Idle take 100 % of cpu;
	else
		cpu = 0;

	cpuProcess = int((((userTimeProcess - s_userTimeProcess) + (kernelTimeProcess - s_kernelTimeProcess)) * 100 ) / div);

	s_time = time;
	s_idleTime = idleTime;
	s_kernelTime = kernelTime;
	s_userTime = userTime;
	s_kernelTimeProcess = kernelTimeProcess;
	s_userTimeProcess = userTimeProcess;
	s_cpu[(s_index ++) %5] = cpu;
	s_cpuProcess[(s_index++) %5] = cpuProcess;
	s_count ++;

	if(s_count > 5)
		s_count = 5;

	cpu = 0;
	int i;
	for(i = 0; i < s_count; i++ )
		cpu += s_cpu[i];
     
	cpuProcess = 0;
	for(i = 0; i < s_count; i++ )
		cpuProcess += s_cpuProcess[i];

	cpu /= s_count;
	cpuProcess /= s_count;   
	s_lastCpu = cpu;
	sLastCpu = s_lastCpu;
	s_TickMark = ::GetTickCount();
    return sLastCpu;
}

Professional System Library on www.prosyslib.org

Re: The way it's supposed to be... [modified]

ejor2-Sep-08 8:40

ejor

2-Sep-08 8:40

I'm very happy you'll find something interresting in my code Poke tongue | ;-P

just use it as you want Rose | [Rose]

Just don't forget a link where you find the code in your project Smile | :)

-----------------------------
ejor @ http://dev.jesover.net

modified on Tuesday, September 2, 2008 2:54 PM

Re: The way it's supposed to be...

Vitaly Tomilov2-Sep-08 8:44

Vitaly Tomilov

2-Sep-08 8:44

Thank you!

And could you, please, explain me the magic of 5 that you used as dimension for two arrays in your code?

Thank you,
Vitaly

Professional System Library on www.prosyslib.org

Re: The way it's supposed to be...

ejor2-Sep-08 9:06

ejor

2-Sep-08 9:06

just an heuristic to have something similar to task manager
You do not want to have all updates
you want something more smooth

Try other way if you prefer Smile | :)

-----------------------------
ejor @ http://dev.jesover.net

Re: The way it's supposed to be...

Vitaly Tomilov2-Sep-08 9:13

Vitaly Tomilov

2-Sep-08 9:13

Got you!

I just wanted to know, since you did not document those things.

And if you think that the shorter code that i published above can be further simplified, please let me know, 'cos i'm still not quite sure about its logic, seems quite a bit different from what you wrote in the article itself where you just give a simple formula, and then the actual code looks way more complicated...

Professional System Library on www.prosyslib.org

Re: The way it's supposed to be...

ejor2-Sep-08 9:19

ejor

2-Sep-08 9:19

I've documented the important part of the algo....
All the rest is just matter of what you need exactly and how you want to use the code Wink | ;)

-----------------------------
ejor @ http://dev.jesover.net

Re: The way it's supposed to be...

Vitaly Tomilov2-Sep-08 9:23

Vitaly Tomilov

2-Sep-08 9:23

Well, you see, i started with the article, tried to implement exactly as the article suggested, but it didn't work, iwas always getting 0% for some reasons that i couldn't understand. So, i ended up taking the original code you wrote and throwing away the parts i didn't need. That told me the article wasn't complete...

And this is what i got now, your own code simplified which i'm still not sure about how it works Smile | :)

, it just does.

Professional System Library on www.prosyslib.org

Re: The way it's supposed to be...

Member 41446493-Dec-08 2:28

Member 4144649

3-Dec-08 2:28

Gents

Thankyou both for givnig me some ideas that have fixed an issue inmy app.

However, in the original code and repeated in Mr Tomilov's there is the passage which is used to build the array for averaging

<br />
        s_cpu[(s_index++) %5] = cpu;<br />
        s_cpuProcess[(s_index++) %5] = cpuProcess;<br />
        s_count ++;<br />
        if( s_count > 5 ) <br />
            s_count = 5;<br />

Was it intended for the s_index to be incremented twice per function call, and won't this cause an interleaving of values, somewhat modifying the result?
Have I missed a cunning deliberate subtlety ?

Yours, slightly baffled.

Re: The way it's supposed to be...

Vitaly Tomilov3-Dec-08 2:41

Vitaly Tomilov

3-Dec-08 2:41

The author commented on this just up as "...just an heuristic to have something similar to task manager".

Professional System Library on www.prosyslib.org

Re: The way it's supposed to be...

Mr Scotty18-Nov-09 22:43

Mr Scotty

18-Nov-09 22:43

Member 4144649 is correct this is a little strange.
the cpu usage array is filled in the order 0,2,4,1,3,0 ...
and cpuProcess in the order 1,3,0,2,4 ...
The first 4 calls don't use the complete array (not filled yet) to calculate the avarage.
The first call uses only index 0 to calculate the avg. For cpuUsage it is not filled (started with 1).
After 5 calls everything is OK. Luckly 5 is an odd number when using an even number it wouldn't work. (0,2,4,0,2,4 when using 6 instead of 5)
It would be better when the code looks something like

s_cpu[s_index] = cpu;
s_cpuProcess[s_index] = cpuProcess;
s_index++;
s_index%=5;

Other improvment would be to have a method to retrieve the process cpu usage value (now only the system cpu usage is returned).

Hope this message was helpfull, keep up the good work.

Re: The way it's supposed to be...

Member 442588919-Mar-10 10:39

Member 4425889

19-Mar-10 10:39

sorry to awaken this dead beast but i am having trouble compiling either pices of code, both the code in the article and the code provided by Vitaly Tomilov.
when i try to compile the code from article it gives me the following error:
\microsoft sdks\windows\v6.0a\include\sdkddkver.h(200) : fatal error C1012: unmatched parenthesis : missing ')'

and when i try to compile the code given by by Vitaly Tomilov it gives me the following error:
..\ProcessorUsage.cpp|89|error: `CCritSecLock' was not declared in this scope|

I would be most great full for any help!

Re: The way it's supposed to be...

Vitaly Tomilov19-Mar-10 11:09

Vitaly Tomilov

19-Mar-10 11:09

CCritSecLock is a standard class from ATL. See file atlbase.h

These are basics, that's probably why people don't bother answering.

Professional System Library on www.prosyslib.org

Re: The way it's supposed to be...

dxj1983102921-Jul-10 18:45

dxj19831029

21-Jul-10 18:45

in stdafx.h line 6,
there is define:
#define _WIN32_WINNT (0x0500) // WE ARE WinNT 5.0 SPECIFIC !!!
block it.
u should be able to compile original code i think, check it.

I did.
Laugh | :laugh:

Good coding practices

Youssef-Gamal-523-Mar-10 23:46

Youssef-Gamal-5

23-Mar-10 23:46

Thanks for sharing your code. Just a cosmetic improvement, consider this snippet:

if (hModule = GetModuleHandle(_T("kernel32.dll")))
{
    if (s_pfnGetSystemTimes = (pfnGetSystemTimes)GetProcAddress(hModule, "GetSystemTimes"))
        return;
}


if (!(hModule = GetModuleHandle(_T("ntdll.dll")))
    return;


if (!(s_pfnNtQuerySystemInformation = (pfnNtQuerySystemInformation)GetProcAddress(hModule, "NtQuerySystemInformation")))
    return;

More readable and in case you want a return value you don't need an else for each if.

Re: The way it's supposed to be...

Vider20-Dec-11 1:29

Vider

20-Dec-11 1:29

Thanks for share to both!

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