Mega Code Archive
How to get the CPU usage in percent on Windows NT2000XP
<![CDATA[
Title: How to get the CPU usage in percent on Windows NT/2000/XP
const
SystemBasicInformation = 0;
SystemPerformanceInformation = 2;
SystemTimeInformation = 3;
type
TPDWord = ^DWORD;
TSystem_Basic_Information = packed record
dwUnknown1: DWORD;
uKeMaximumIncrement: ULONG;
uPageSize: ULONG;
uMmNumberOfPhysicalPages: ULONG;
uMmLowestPhysicalPage: ULONG;
uMmHighestPhysicalPage: ULONG;
uAllocationGranularity: ULONG;
pLowestUserAddress: Pointer;
pMmHighestUserAddress: Pointer;
uKeActiveProcessors: ULONG;
bKeNumberProcessors: byte;
bUnknown2: byte;
wUnknown3: word;
end;
type
TSystem_Performance_Information = packed record
liIdleTime: LARGE_INTEGER; {LARGE_INTEGER}
dwSpare: array[0..75] of DWORD;
end;
type
TSystem_Time_Information = packed record
liKeBootTime: LARGE_INTEGER;
liKeSystemTime: LARGE_INTEGER;
liExpTimeZoneBias: LARGE_INTEGER;
uCurrentTimeZoneId: ULONG;
dwReserved: DWORD;
end;
var
NtQuerySystemInformation: function(infoClass: DWORD;
buffer: Pointer;
bufSize: DWORD;
returnSize: TPDword): DWORD; stdcall = nil;
liOldIdleTime: LARGE_INTEGER = ();
liOldSystemTime: LARGE_INTEGER = ();
function Li2Double(x: LARGE_INTEGER): Double;
begin
Result := x.HighPart * 4.294967296E9 + x.LowPart
end;
procedure GetCPUUsage;
var
SysBaseInfo: TSystem_Basic_Information;
SysPerfInfo: TSystem_Performance_Information;
SysTimeInfo: TSystem_Time_Information;
status: Longint; {long}
dbSystemTime: Double;
dbIdleTime: Double;
bLoopAborted : boolean;
begin
if @NtQuerySystemInformation = nil then
NtQuerySystemInformation := GetProcAddress(GetModuleHandle('ntdll.dll'),
'NtQuerySystemInformation');
// get number of processors in the system
status := NtQuerySystemInformation(SystemBasicInformation, @SysBaseInfo, SizeOf(SysBaseInfo), nil);
if status 0 then Exit;
// Show some information
with SysBaseInfo do
begin
ShowMessage(
Format('uKeMaximumIncrement: %d'#13'uPageSize: %d'#13+
'uMmNumberOfPhysicalPages: %d'+#13+'uMmLowestPhysicalPage: %d'+#13+
'uMmHighestPhysicalPage: %d'+#13+'uAllocationGranularity: %d'#13+
'uKeActiveProcessors: %d'#13'bKeNumberProcessors: %d',
[uKeMaximumIncrement, uPageSize, uMmNumberOfPhysicalPages,
uMmLowestPhysicalPage, uMmHighestPhysicalPage, uAllocationGranularity,
uKeActiveProcessors, bKeNumberProcessors]));
end;
bLoopAborted := False;
while not bLoopAborted do
begin
// get new system time
status := NtQuerySystemInformation(SystemTimeInformation, @SysTimeInfo, SizeOf(SysTimeInfo), 0);
if status 0 then Exit;
// get new CPU's idle time
status := NtQuerySystemInformation(SystemPerformanceInformation, @SysPerfInfo, SizeOf(SysPerfInfo), nil);
if status 0 then Exit;
// if it's a first call - skip it
if (liOldIdleTime.QuadPart 0) then
begin
// CurrentValue = NewValue - OldValue
dbIdleTime := Li2Double(SysPerfInfo.liIdleTime) - Li2Double(liOldIdleTime);
dbSystemTime := Li2Double(SysTimeInfo.liKeSystemTime) - Li2Double(liOldSystemTime);
// CurrentCpuIdle = IdleTime / SystemTime
dbIdleTime := dbIdleTime / dbSystemTime;
// CurrentCpuUsage% = 100 - (CurrentCpuIdle * 100) / NumberOfProcessors
dbIdleTime := 100.0 - dbIdleTime * 100.0 / SysBaseInfo.bKeNumberProcessors + 0.5;
// Show Percentage
Form1.Label1.Caption := FormatFloat('CPU Usage: 0.0 %',dbIdleTime);
Application.ProcessMessages;
// Abort if user pressed ESC or Application is terminated
bLoopAborted := (GetKeyState(VK_ESCAPE) and 128 = 128) or Application.Terminated;
end;
// store new CPU's idle and system time
liOldIdleTime := SysPerfInfo.liIdleTime;
liOldSystemTime := SysTimeInfo.liKeSystemTime;
// wait one second
Sleep(1000);
end;
end;
procedure TForm1.Button1Click(Sender: TObject);
begin
GetCPUUsage
end;
]]>