linux-kernel - Re: [Bug 212265] New: clock_gettime(CLOCK_TAI, ...) should return an error when TAI has not been configured

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Date:   Mon, 29 Mar 2021 07:21:22 -0700
From:   Richard Cochran <richardcochran@...il.com>
To:     Miroslav Lichvar <mlichvar@...hat.com>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Daphne Preston-Kendall <dpk@...ceword.org>,
        LKML <linux-kernel@...r.kernel.org>,
        John Stultz <john.stultz@...aro.org>,
        "Michael Kerrisk (man-pages)" <mtk.manpages@...il.com>
Subject: Re: [Bug 212265] New: clock_gettime(CLOCK_TAI, ...) should return an
 error when TAI has not been configured

On Mon, Mar 29, 2021 at 11:16:48AM +0200, Miroslav Lichvar wrote:
> On Fri, Mar 26, 2021 at 08:28:59PM -0700, Richard Cochran wrote:
> > Using ntpd on Debian, the service will set the offset, but only after
> > synchronization with the upstream server has been established, and
> > this takes about five minutes, IIRC.
> 
> With the iburst option it shouldn't take more than 10 seconds. There
> might be an issue wrt stepping the clock when the initial offset is
> large.

Really?  Debian has 

    # pool.ntp.org maps to about 1000 low-stratum NTP servers.  Your server will
    # pick a different set every time it starts up.  Please consider joining the
    # pool: <http://www.pool.ntp.org/join.html>
    pool 0.debian.pool.ntp.org iburst
    pool 1.debian.pool.ntp.org iburst
    pool 2.debian.pool.ntp.org iburst
    pool 3.debian.pool.ntp.org iburst

I guess I'll measure again, but I'm pretty sure it took a long time to
get to TAI being set.

> In Fedora and derived distros using chrony by default the
> TAI-UTC offset should be set right on the first update of the clock as
> expected.

(Maybe it is time to switch to chrony ;)

Thanks,
Richard