The system clock may run fast when you use the ACPI power management timer as a high-resolution counter on Windows 2000, XP and 2003

The system clock may run fast when you use the ACPI power management timer as a high-resolution counter on Windows 2000-based, Windows XP-based, and Windows Server 2003-based computers.


SYMPTOMS

When a Microsoft Windows 2000-based, Windows XP-based, or Windows Server 2003-based computer runs in Advanced Configuration and Power Interface (ACPI) mode and uses a high-resolution counter, the system clock may run fast.


CAUSE


This issue may occur if the time increment in a program changes and the Hardware Abstraction Layer (HAL) cannot measure the time interval between successive clock interrupts. This causes the system clock to lose a short period of time. When the HAL misses many time-interval measurements in quick succession, the time loss may be significant.

Note

· This issue may occur on a computer that is running Halaacpi.dll (UP, ACPI, or APIC), Halmacpi.dll (MP, ACPI, or APIC), and Halmps.dll (MP, non-ACPI, or legacy) because these DLLs use the Real Time Clock (RTC) to generate clock interrupts.

· This issue does not occur on a computer that is running Halacpi.dll (UP, ACPI, or PIC) or Halx86.dll (UP, non-ACPI, or legacy) because these DLLs use the 8254 Programmable Interval Timer (PIT) to generate clock interrupts.


WORKAROUND


To work around this issue, use one of the following methods:

· Modify the program to call the timeBeginPeriod function at startup and to call the timeEndPeriod function on exit. This workaround eliminates repeated time increment changes.

· Modify the program to use the QueryPerformanceCounter() API.

Link: http://support.microsoft.com/kb/821893