| Re: [chrony-dev] chronyd broken on macOS Big Sur |
[ Thread Index |
Date Index
| More chrony.tuxfamily.org/chrony-dev Archives
]
- To: chrony-dev@xxxxxxxxxxxxxxxxxxxx
- Subject: Re: [chrony-dev] chronyd broken on macOS Big Sur
- From: Miroslav Lichvar <mlichvar@xxxxxxxxxx>
- Date: Thu, 27 Aug 2020 08:52:35 +0200
- Authentication-results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=mlichvar@xxxxxxxxxx
- Dkim-signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1598511160; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=orGT6J67N8K8wdu5oQefn9Dv/HO+/xqHEb4SMHkHb94=; b=UfoUqFhp4nBoUMVzlAMdsspwdPJbsn+MAoE2RZJRj4z3SK14NI93oNpsE/g9T/e76wMivK 4pzu0HLkUwJHrO6cxQ2Dw54awlLZJLWL76csorm+YtTj0LT6SLu5Z2DirHvXKaOdH3hBK6 HV3TorBUvgkhPeWGJ5/jSqE0PYlSBVM=
On Thu, Aug 27, 2020 at 11:41:44AM +1200, Bryan Christianson wrote:
> It worked!!! I left the daemon running for over 30 minutes and it held the system time to +/- 5 usecs of NTP, (mostly better than +/- 1usec). The timed daemon did NOT change the clock at all during this test and chronyd behaved as expected.
That's good to hear.
>
> I repeated the test with ntp_adjtime() enabled and kept a log of debug messages (attached). A simple analysis of the debug trace seems to say that the reference clock is leaping about, but I proved that it isn't with my first adjtime() test. Also the reference clock works perfectly with earlier versions of macOS, my linux machines etc.
>
> My current conclusion is that the Darwin kernel in Big Sur has a bad implementation of ntp_adjtime() that somehow causes the clock to jump by random intervals. I would really appreciate help in building a *simple* program to be able to demonstrate this to Apple in a new bug report.
You could start with the test/kernel/ntpadjtime.c program, modified to
very slowly change the frequency of the clock, e.g. 1 ppm per minute.
If you run at the same time chronyd with the -x option and a short
polling interval, you should see in the tracking log when the
offset jumped.
--
Miroslav Lichvar
--
To unsubscribe email chrony-dev-request@xxxxxxxxxxxxxxxxxxxx with "unsubscribe" in the subject.
For help email chrony-dev-request@xxxxxxxxxxxxxxxxxxxx with "help" in the subject.
Trouble? Email listmaster@xxxxxxxxxxxxxxxxxxxx.