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RE: More Wallclock questions
- From: Jesper Skov <jskov at redhat dot com>
- To: Damir Salantic <damir at INTESIS dot hr>
- Cc: eCos Discuss <ecos-discuss at sources dot redhat dot com>
- Date: 05 Dec 2001 11:04:27 +0100
- Subject: RE: [ECOS] More Wallclock questions
- References: <000101c17d6c$d8a95300$7200a8c0@damir>
On Wed, 2001-12-05 at 10:11, Damir Salantic wrote:
> So, kernel realtime clock is actually synchronized with wallclock in the
> initialization and later when you want to read wallclock you actually read
> kernel clock.
Note that on some platforms the kernel clock may not be accurate over
long periods of time.
This can be caused by (a) inaccuracy in timer programming [even if it's
accurate to 0.1% of the 100Hz ticks, the error will accumulate over
time], and (b) delays in reloading the timer [some platforms do not have
automatic reload of the timer counter, so disabling interrupts may cause
(minimal) timer drift, which again accumulates over time].
Jesper