System Clock Appears to Lose About One Second per Hour (106434)
The information in this article applies to:
- Microsoft Windows NT Server 3.1
- Microsoft Windows NT Workstation 3.1
- Microsoft Windows NT Advanced Server
This article was previously published under Q106434 SYMPTOMS
If the time is continuously read on an x86-based Windows NT machine,
the system appears to lose a second each hour.
CAUSE
The Real Time Clock (RTC) in x86-based computers has a resolution of
one second. Therefore, the Hardware Abstraction Layer (HAL) on x86
platforms uses an interval timer to increase the resolution of the
system clock into the millisecond range. Windows NT's calculation of
real time based on this interval timer is inaccurate enough that it
could get out of sync by over a second every hour.
RESOLUTION
The calculations to determine the correct time for the system clock
based on the interval timer has been improved so that it remains much
closer in sync with the RTC. The system clock is still resynchronized
every hour but the size of the adjustment is negligible (at most, a
few milliseconds).
This was fixed within HAL.DLL for x86 based systems only. This is not
a concern on MIPS or Alpha platforms.
Modification Type: | Major | Last Reviewed: | 11/20/2003 |
---|
Keywords: | KB106434 |
---|
|