Andrei Borzenkov wrote:

В Sat, 14 Mar 2015 11:36:02 +0100 Per Jessen пишет:

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I see this message quite frequently in the log on my xen guest systems - I'm guessing it's an indication that ntp on the xen host adjusted the clock. About once every minute, right now 793 times since midnight - that seems a bit too much?

And how is it related to systemd?

The messages seem to come from systemd: 2015-03-14T11:31:09+01:00 dupont8 systemd[1998]: Time has been changed 2015-03-14T11:32:09+01:00 dupont8 systemd[1]: Time has been changed 2015-03-14T11:33:10+01:00 dupont8 systemd[1]: Time has been changed 2015-03-14T11:33:10+01:00 dupont8 systemd[1998]: Time has been changed -- Per Jessen, Zürich (5.1°C) http://www.hostsuisse.com/ - dedicated server rental in Switzerland. -- To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org To contact the owner, e-mail: opensuse+owner@opensuse.org

Andrei Borzenkov wrote:

В Sat, 14 Mar 2015 14:54:44 +0100 Per Jessen пишет:

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Andrei Borzenkov wrote:

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В Sat, 14 Mar 2015 11:36:02 +0100 Per Jessen пишет:

...

I see this message quite frequently in the log on my xen guest systems - I'm guessing it's an indication that ntp on the xen host adjusted the clock. About once every minute, right now 793 times since midnight - that seems a bit too much?

And how is it related to systemd?

The messages seem to come from systemd:

2015-03-14T11:31:09+01:00 dupont8 systemd[1998]: Time has been changed 2015-03-14T11:32:09+01:00 dupont8 systemd[1]: Time has been changed 2015-03-14T11:33:10+01:00 dupont8 systemd[1]: Time has been changed 2015-03-14T11:33:10+01:00 dupont8 systemd[1998]: Time has been changed

It is just a messenger here. Systemd receives notification when time gets reset and logs it. You need to look for what is resetting time.

Well, presumably it's the xen host's ntpd. -- Per Jessen, Zürich (5.1°C) http://www.hostsuisse.com/ - virtual servers, made in Switzerland. -- To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org To contact the owner, e-mail: opensuse+owner@opensuse.org

ianseeks wrote:

On Sunday 15 Mar 2015 00:16:49 Per Jessen wrote:

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Andrei Borzenkov wrote:

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В Sat, 14 Mar 2015 14:54:44 +0100

Per Jessen пишет:

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Andrei Borzenkov wrote:

...

В Sat, 14 Mar 2015 11:36:02 +0100

Per Jessen пишет:

...

I see this message quite frequently in the log on my xen guest systems - I'm guessing it's an indication that ntp on the xen host adjusted the clock. About once every minute, right now 793 times since midnight - that seems a bit too much?

And how is it related to systemd?

The messages seem to come from systemd:

2015-03-14T11:31:09+01:00 dupont8 systemd[1998]: Time has been changed 2015-03-14T11:32:09+01:00 dupont8 systemd[1]: Time has been changed 2015-03-14T11:33:10+01:00 dupont8 systemd[1]: Time has been changed 2015-03-14T11:33:10+01:00 dupont8 systemd[1998]: Time has been changed

It is just a messenger here. Systemd receives notification when time gets reset and logs it. You need to look for what is resetting time.

Well, presumably it's the xen host's ntpd.

you would think that the app posting the message would identify itself

Well, it's quite clearly systemd, but as Andrei says, systemd is just the messenger. Looking at a xen guest this morning, I see the message twice every minute, steady as clockwork :-) In total 1439 messages right now. As I don't see this message on other systems, I am assuming it is related to these systems being xen guests. Funny, I googled "Time has been changed systemd xen", and the topmost hit was my posting that you replied to. -- Per Jessen, Zürich (3.5°C) http://www.dns24.ch/ - your free DNS host, made in Switzerland. -- To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org To contact the owner, e-mail: opensuse+owner@opensuse.org

ianseeks wrote:

On Monday 16 Mar 2015 07:45:21 Per Jessen wrote:

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ianseeks wrote:

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On Sunday 15 Mar 2015 00:16:49 Per Jessen wrote:

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Andrei Borzenkov wrote:

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В Sat, 14 Mar 2015 14:54:44 +0100

Per Jessen пишет:

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Andrei Borzenkov wrote: > В Sat, 14 Mar 2015 11:36:02 +0100 > > Per Jessen пишет: >> I see this message quite frequently in the log on my xen >> guest systems - I'm guessing it's an indication that ntp on >> the xen host >> adjusted the clock. About once every minute, right now 793 >> times since midnight - that seems a bit too much? > > And how is it related to systemd?

The messages seem to come from systemd:

2015-03-14T11:31:09+01:00 dupont8 systemd[1998]: Time has been changed 2015-03-14T11:32:09+01:00 dupont8 systemd[1]: Time has been changed 2015-03-14T11:33:10+01:00 dupont8 systemd[1]: Time has been changed 2015-03-14T11:33:10+01:00 dupont8 systemd[1998]: Time has been changed

It is just a messenger here. Systemd receives notification when time gets reset and logs it. You need to look for what is resetting time.

Well, presumably it's the xen host's ntpd.

you would think that the app posting the message would identify itself

Well, it's quite clearly systemd, but as Andrei says, systemd is just the messenger. Looking at a xen guest this morning, I see the message twice every minute, steady as clockwork :-) In total 1439 messages right now.

so is it just systemd monitoring the change on the system and reporting it rather than actually changing it?

I think so yes. Monitoring or being notified by <something> that is monitoring. What I'd like to understand is - - why is it being changed - who is changing it -- Per Jessen, Zürich (5.4°C) http://www.hostsuisse.com/ - virtual servers, made in Switzerland. -- To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org To contact the owner, e-mail: opensuse+owner@opensuse.org

On Mon, 16 Mar 2015 09:46, Per Jessen wrote:

Per Jessen wrote:

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ianseeks wrote:

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On Monday 16 Mar 2015 07:45:21 Per Jessen wrote:

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On Sunday 15 Mar 2015 00:16:49 Per Jessen wrote:

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On Sat, 14 Mar 2015 14:54:44 +0100 Andrei Borzenkov wrote: > Per Jessen wrote: >> On Sat, 14 Mar 2015 11:36:02 +0100 Andrei Borzenkov wrote: >>> Per Jessen wrote: [snip] Well, it's quite clearly systemd, but as Andrei says, systemd is just

ianseeks wrote: the messenger. Looking at a xen guest this morning, I see the message twice every minute, steady as clockwork :-) In total 1439 messages right now.

so is it just systemd monitoring the change on the system and reporting it rather than actually changing it?

I think so yes. Monitoring or being notified by <something> that is monitoring. What I'd like to understand is -

systemd appears to be monitoring it:

from src/core/manager.c:

/* Uses TFD_TIMER_CANCEL_ON_SET to get notifications whenever * CLOCK_REALTIME makes a jump relative to CLOCK_MONOTONIC */

I won't pretend to understand what that means :-(

A hunch: the 'internal' clock in the xen guest runs to fast/slow, compared to RTC and is reset/corrected by ntp once a minute. Thus the 'MONOTONIC' is broken (a time stamp occures twice), and the message is send. Check the mobo nvclock / kernel time div (adjtimex, ntp logs), and do the same in the xen client. At more than a 1/1000 (1ms per 1s) systematic drift / divergence it gets ugly (in terms of messages). The better the systematic drift is accounted for, the less ntp has to do, the less messages you get. - Yamaban. -- To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org To contact the owner, e-mail: opensuse+owner@opensuse.org

-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA256 On 2015-03-16 12:05, Per Jessen wrote:

Yamaban wrote:

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A hunch: the 'internal' clock in the xen guest runs to fast/slow, compared to RTC and is reset/corrected by ntp once a minute. Thus the 'MONOTONIC' is broken (a time stamp occures twice), and the message is send.

I'm not running ntp on the xen guests - it seems to be superfluous when the host is keeping the clock sync'ed. Maybe that assumption is flawed?

I think it is correct. I'm not familiar with xen, but I read a similar recommendation from vmware people: do not run ntpd on guests, but instead use guest tools to sync time with host. How xen handle things I do not know, but I guess that, similarly, you should not try to discipline its clock. However, ntpd on the host should be changing the clock so slowly that nothing should notice it. Otherwise, the logs on the host might tell something about those changes. - -- Cheers / Saludos, Carlos E. R. (from 13.1 x86_64 "Bottle" (Minas Tirith)) -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.22 (GNU/Linux) iF4EAREIAAYFAlUHF3kACgkQja8UbcUWM1y0cAD/dJ30tbVHmVZ46uhQEPxJut8A a+VHvrvvXmemU2tnF9QA/i2ol2DSVQOrMQ0x6pzuW4RNax9BdPEyB9DPrs8SSrt3 =Flli -----END PGP SIGNATURE----- -- To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org To contact the owner, e-mail: opensuse+owner@opensuse.org

-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA256 On 2015-03-17 12:24, Per Jessen wrote:

Carlos E. R. wrote:

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How xen handle things I do not know, but I guess that, similarly, you should not try to discipline its clock.

I've got ntpd running fine on the host, no problems.

That's what I mean, do it on the host, not the guest. - -- Cheers / Saludos, Carlos E. R. (from 13.1 x86_64 "Bottle" (Minas Tirith)) -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.22 (GNU/Linux) iF4EAREIAAYFAlUIhd0ACgkQja8UbcUWM1zYdgEAl0cr/I9dqCvr7MWXGZARw5d1 zJb87/4BSZQ4m7kNfE8A/2v3wFZ8c0bW3qwZzQ/oXETAdg/toeBhgblgwso3nNe7 =kGlr -----END PGP SIGNATURE----- -- To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org To contact the owner, e-mail: opensuse+owner@opensuse.org