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Date: Sat, 30 Nov 2013 12:03:06 +0100
From: =?UTF-8?B?Um9nZXIgUGF1IE1vbm7DqQ==?= <roger.pau@citrix.com>
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To: Karl Pielorz <kpielorz_lst@tdx.co.uk>, <freebsd-xen@freebsd.org>
Subject: Re: Xen Guests / NTP best practice?
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On 30/11/13 11:52, Karl Pielorz wrote:
> 
> 
> --On 29 November 2013 18:43:32 +0100 Roger Pau Monné
> <roger.pau@citrix.com> wrote:
> 
>> There have been some improvements in 10 regarding timekeeping, now
>> FreeBSD makes use of the PV timer and PV clock when running under HVM,
>> which should be more stable.
>>
>> Could you try if your issues with ntp are reproducible on 10?
> 
> Sure, I'll give 10 a go. Does the above mean for a VM you don't need to
> run ntp? (i.e. it'll stay in sync with dom0 / the XenServer?) - or is
> ntp still necessary?

Well, if the Dom0 is keep in sync, the DomU clock should also be in
sync, but I'm not sure how often does FreeBSD poll the underlying clock,
so I would recommend running ntp even in that case (certainly it's not
going to hurt).

> Likewise do you know if there is any recommended solution for 9.x (which
> is the bulk of our VM's).

Apart from ntp/ntpdate, I cannot think of anything else. Backporting the
changes from 10 is certainly not going to be easy.

Roger.