Re: 2.6.19-rc2 and very unstable NTP

From: Roman Zippel
Date: Thu Oct 26 2006 - 19:07:06 EST


Hi,

On Thu, 26 Oct 2006, john stultz wrote:

> One of the recent changes was removing the in-kernel PPS code. This was
> done because there were no in-kernel users of the interface (the only
> ones being I believe in a variant of this LinuxPPS patch). While from
> the diffstat below it doesn't look like the patch affects the
> timekeeping code, it would be good to first reproduce the issue without
> the patch.

The recent patch by Jim Houston explains the misbehaviour. It seems the
ntp daemon uses ADJ_OFFSET_SINGLESHOT for time adjustments, which is
rather coarse-grained. By adding proper PPS support one should be able to
get a more stable clock, but it's better done by someone who has the
hardware to test this.

bye, Roman
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