Groups search result 4 for system idle cpu usage api |
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Your probably right about the variant, but I didn't know how to
translate a PVOID, probably should be LONG. Anyway, here's the
C++ code for a program that extracts the CPU usage from the
system using this NtQuerySystemInformation API.
#include <windows.h>
#include <conio.h>
#include <stdio.h>
#define SystemBasicInformation 0
#define SystemPerformanceInformation 2
#define SystemTimeInformation 3
#define Li2Double(x) ((double)((x).HighPart) * 4.294967296E9 +
(double)((x).LowPart))
typedef struct
{
DWORD dwUnknown1;
ULONG uKeMaximumIncrement;
ULONG uPageSize;
ULONG uMmNumberOfPhysicalPages;
ULONG uMmLowestPhysicalPage;
ULONG uMmHighestPhysicalPage;
ULONG uAllocationGranularity;
PVOID pLowestUserAddress;
PVOID pMmHighestUserAddress;
ULONG uKeActiveProcessors;
BYTE bKeNumberProcessors;
BYTE bUnknown2;
WORD wUnknown3;
} SYSTEM_BASIC_INFORMATION;
typedef struct
{
LARGE_INTEGER liIdleTime;
DWORD dwSpare[76];
} SYSTEM_PERFORMANCE_INFORMATION;
typedef struct
{
LARGE_INTEGER liKeBootTime;
LARGE_INTEGER liKeSystemTime;
LARGE_INTEGER liExpTimeZoneBias;
ULONG uCurrentTimeZoneId;
DWORD dwReserved;
} SYSTEM_TIME_INFORMATION;
// ntdll!NtQuerySystemInformation (NT specific!)
//
// The function copies the system information of the
// specified type into a buffer
//
// NTSYSAPI
// NTSTATUS
// NTAPI
// NtQuerySystemInformation(
// IN UINT SystemInformationClass, // information type
// OUT PVOID SystemInformation, // pointer to buffer
// IN ULONG SystemInformationLength, // buffer size in bytes
// OUT PULONG ReturnLength OPTIONAL // pointer to a 32-bit
// // variable that
receives
// // the number of bytes
// // written to the
buffer
// );
typedef LONG (WINAPI *PROCNTQSI)(UINT,PVOID,ULONG,PULONG);
PROCNTQSI NtQuerySystemInformation;
void main(void)
{
SYSTEM_PERFORMANCE_INFORMATION SysPerfInfo;
SYSTEM_TIME_INFORMATION SysTimeInfo;
SYSTEM_BASIC_INFORMATION SysBaseInfo;
double dbIdleTime;
double dbSystemTime;
LONG status;
LARGE_INTEGER liOldIdleTime = {0,0};
LARGE_INTEGER liOldSystemTime = {0,0};
NtQuerySystemInformation = (PROCNTQSI)GetProcAddress(
GetModuleHandle
("ntdll"),
"NtQuerySystemInformatio
n"
);
if (!NtQuerySystemInformation)
return;
// get number of processors in the system
status = NtQuerySystemInformation
(SystemBasicInformation,&SysBaseInfo,sizeof(SysBaseInfo),NULL);
if (status != NO_ERROR)
return;
printf("\nCPU Usage (press any key to exit): ");
while(!_kbhit())
{
// get new system time
status = NtQuerySystemInformation
(SystemTimeInformation,&SysTimeInfo,sizeof(SysTimeInfo),0);
if (status!=NO_ERROR)
return;
// get new CPU's idle time
status = NtQuerySystemInformation
(SystemPerformanceInformation,&SysPerfInfo,sizeof
(SysPerfInfo),NULL);
if (status != NO_ERROR)
return;
// if it's a first call - skip it
if (liOldIdleTime.QuadPart != 0)
{
// 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 / (double)
SysBaseInfo.bKeNumberProcessors + 0.5;
printf("\b\b\b\b%3d%%",(UINT)dbIdleTime);
}
// store new CPU's idle and system time
liOldIdleTime = SysPerfInfo.liIdleTime;
liOldSystemTime = SysTimeInfo.liKeSystemTime;
// wait one second
Sleep(1000);
} printf("\n");
}
If someone could help translate just the actual
NtQuerySystemInformation API to VBasic 5.0 I'd be greatly
indebted. I think the main problem to worry about is that the
NTDLL.DLL isn't available to applications (at least I've
heard). I think this is why the author of the above code chose
to use the GetProcAddress() function to get the handle of the
DLL for the call. I don't know how this would translate to VB,
but I do know that just when I think something can't be done in
VB, I figure it out and it works.
Thanks
Jm
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