Re: [chrony-dev] macOS 13: suspicious jumps while sleeping

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> On 22/11/2017, at 9:15 PM, Miroslav Lichvar <mlichvar@xxxxxxxxxx> wrote:
> 
> On Wed, Nov 22, 2017 at 02:03:17PM +0700, Gerriet M. Denkmann wrote:
>> macOS 13.1, chrony 3.2.
>> 
>> I modified check_current_time() in sched.c:
>>    LOG(LOGS_WARN, "Forward time jump detected! %4ld sec”, raw->tv_sec - (prev_raw->tv_sec + elapsed_max.tv_sec) );
>> 
>> After the computer has been sleeping for some time (since about 10:10), I saw:
> 
> The computer has woken up only once and there are multiple messages
> saying the clock jumped forward? That is weird. Any chance the new
> timed daemon is interfering with the clock? There was a post on the
> -users list how it can be disabled.

This looks like the 'timed' problem. Here is what I posted to the users list.

There is a bug in High Sierra (macOS 10.13) that leaves Apple's timed daemon active after it has been disabled in the System Settings 'Date and Time' preferences

timed continues to send NTP packets to the server specified in the System Preferences and then adjusts the system clock. This of course has a terrible effect on chronyd, with frequency and offsets jumping all over the place.

I have reported the bug to Apple so hopefully it will be fixed in some forthcoming patch release of macOS 10.13

It does not seem to be possible to permanently stop/disable the timed service via the launchctl mechanism.

In the interim, the only solution I have been able to come up with is to enable automatic time adjustments and then set the NTP server name to some fictitious name that has no IP address. After changing the name, then once again disable automatic time adjustments.  timed will continue to run but fail in its attempts to get valid NTP responses. Its ugly, but it seems to work.



Bryan Christianson
bryan@xxxxxxxxxxxxx




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