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Bug#854444: marked as done (linux-image-4.9.0-0.bpo.1-amd64-unsigned: System time divergence with HyperV TimeSync protocol version 4)

Your message dated Sun, 23 May 2021 20:49:24 +0200
with message-id <E1lktA5-0006HY-K3@hullmann.westfalen.local>
and subject line Closing this bug
has caused the Debian Bug report #854444,
regarding linux-image-4.9.0-0.bpo.1-amd64-unsigned: System time divergence with HyperV TimeSync protocol version 4
to be marked as done.

This means that you claim that the problem has been dealt with.
If this is not the case it is now your responsibility to reopen the
Bug report if necessary, and/or fix the problem forthwith.

(NB: If you are a system administrator and have no idea what this
message is talking about, this may indicate a serious mail system
misconfiguration somewhere. Please contact owner@bugs.debian.org
immediately.)


-- 
854444: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=854444
Debian Bug Tracking System
Contact owner@bugs.debian.org with problems
--- Begin Message --- 
Package: linux-image-4.9.0-0.bpo.1-amd64-unsigned
Version: 4.9.2-2~bpo8+1
Severity: important
Tags: upstream

Since using the linux-image-4.9.0-0.bpo.1-amd64 kernel, some of our Jessie
systems running under HyperV virtualization show an enormous time divergence
gradually building up over some hours (see attached graphs from our NTP
monitoring).
System time and NTP time converge to approx. 10 minutes every approx. 8 hours
(though some machines diverge forwards and some backwards...). Especially
jumping backwards in time can be critical for various applications.
Additionally, Systemd prints "Time has been changed" to the syslog every 5
seconds, which is a little bit annoying.

In upstream, there is a patch under development that drops in-kernel time
adjustments and exposes the TimeSync messages as a PTP device for consumation
by an NTP client: https://lkml.org/lkml/2017/1/30/232.

I don't know whether this classifies as some kind of brokenness on some
hardware (e.g. HyperV 2016)...
A possible workaround of course is to just disable Time Synchronisation in the
Guest Additions setting in HyperV.

Best regards,
Moritz



-- System Information:
Debian Release: 8.7
  APT prefers stable-updates
  APT policy: (700, 'stable-updates'), (700, 'stable'), (60, 'testing')
Architecture: amd64 (x86_64)

Kernel: Linux 3.16.0-4-amd64 (SMP w/8 CPU cores)
Locale: LANG=en_US.utf8, LC_CTYPE=en_US.utf8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)

Attachment: ilias-ng-db-01_ntptime_2daily.png
Description: PNG image

Attachment: tsmdbbackup-01_ntptime_2daily.png
Description: PNG image


--- End Message ---
--- Begin Message --- 
This bug was filed for a very old kernel. If you can reproduce it with
- the current version in unstable/testing
- the latest kernel from buster.backports
please reopen the bug, see https://www.debian.org/Bugs/server-control

--- End Message ---
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