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 = ();
   Usage: Double;
 
 
 procedure GetCPUUsage;
 var
   SysBaseInfo: TSystem_Basic_Information;
   SysPerfInfo: TSystem_Performance_Information;
   SysTimeInfo: TSystem_Time_Information;
   status: Longint; {long}
   dbSystemTime: Double;
   dbIdleTime: Double;
 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;
   // get new system time
  status := NtQuerySystemInformation(SystemTimeInformation, @SysTimeInfo, SizeOf
                                      (SysTimeInfo), nil);
   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
    Usage := dbIdleTime;
     if Usage>100 then
       Usage := 100
   end;
   // store new CPU's idle and system time
  liOldIdleTime := SysPerfInfo.liIdleTime;
   liOldSystemTime := SysTimeInfo.liKeSystemTime
 end;