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Re: PPS in GPSD vs Chrony

From: Gary E. Miller
Subject: Re: PPS in GPSD vs Chrony
Date: Wed, 1 Jul 2020 10:25:30 -0700

Yo Miroslav!

On Wed, 1 Jul 2020 15:49:37 +0200
Miroslav Lichvar <> wrote:

> > Interesting.  Do you have data on this configuration compared to
> > plain PPS?  
> Here is a quick test comparing the PPS rate of 32 and 1 Hz. The
> polling interval didn't change (1 second) and it was running on an
> idle system (an Orange Pi PC). The RMS offset value is about 4.7 ns vs
> 13.5 ns, so the improvement is not as good as the square root of the
> rate ratio, but still significant.

If the poll rate stays at 1Hz then why does a higher "PPS" help?  Maybe
it keeps chronyd (I assume you are using chronyd) fresh in the CPU
cache and running on its own core.  This is an odd one.

Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703  Tel:+1 541 382 8588

            Veritas liberabit vos. -- Quid est veritas?
    "If you can't measure it, you can't improve it." - Lord Kelvin

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