In the guests' VMDBKs, in the SIEBK is stored the offset from the hardware
clock that gets loaded when the guest is run.  I don't recall the offset in
the block.  Unless that's different they should both be seeing the same CPU
clock.

--
Mike Harding
z/VM System Support
/sp


Linux on 390 Port <[email protected]> wrote on 07/20/2016 01:42:05
PM:

> From: Marcy Cortes <[email protected]>
> To: [email protected]
> Date: 07/20/2016 01:42 PM
> Subject: Back to the future?
> Sent by: Linux on 390 Port <[email protected]>
>
> So we have some servers that pass timestamps around to see how long
> they have to do something before throwing in the towel.
>
> They've recently put in some logging to debug some errors and have
> found some cases of going back in time.
>
> TmsSent 2016-07-20 07:40:07.000034 | TrapRx 2016-07-20 07:40:06.000944
>
> So back in time by nearly a second (.99909).
>
> These 2 servers are on the same VM system.  Both run NTP.
> We know things get really out of whack without NTP.  We had a bug
> where it didn't start and things got really confused.
>
> Could NTP be misbehaving?  It was just patched.   How can I prove
> that the clocks on the 2 servers have a different time so that I can
> ascertain if it is NTP or something else.
>
>
>
> Marcy
>
>
>
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