Yo Miroslav!
On Wed, 4 Mar 2015 09:24:33 +0100
Miroslav Lichvar <mlich...@redhat.com> wrote:
> On Tue, Mar 03, 2015 at 11:44:47AM -0800, Gary E. Miller wrote:
> > Miroslav Lichvar <mlich...@redhat.com> wrote:
> > > On Tue, Mar 03, 2015 at 12:38:41AM -0800, Gary E. Miller wrote:
> > > > First, why does chronyd not support uSec SHM? (I usually use
> > > > the SOCK)
> > >
> > > It does support both microsecond and nanosecond resolution in SHM.
> >
> > Very odd. That is not what I have been seeing, so instead of
> > unimplemented it must be broken.
>
> What exactly do you see?
I feed my PPS by way of gpsd to chronyd using SHM and SOCK at the same
time. The SOCK was running jitter around 200 nSec and the SHM around
1500 nSec.
When I set chrony.conf to use precision 1e-9 for SHM 1 the two clocks
started to basically agree. No long term testing, but short term it
looks like the precision was holding a floor under the jitter. Not
something I see on ntpd.
Maybe a good thing, maybe not, but could be documented better. It is
not how ntpd does it.
> > So if the offset is zero it is set to the dispersion? That is not
> > good.
>
> No, the offset will be still zero, but dispersion will be set to
> precision. Here is an example.
Ah, makes sense now. Thank you.
Which still leaves me with slave PHC clocks that either go crazy or have
huge offsets...
I have two live test beds now and I'mm getting a better feel for the failure
mechanisms.
It almost feels like the sign of the offset is wrong on the I210. As
soon as ntpd/chronyd steers to it the time blows up. Positive, not
negative feedback.
RGDS
GARY
---------------------------------------------------------------------------
Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97701
g...@rellim.com Tel:+1(541)382-8588
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