lkml.org 
[lkml]   [2014]   [Sep]   [25]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH] Drivers: hv: util: Implement Time Synchronization using host time sample
On Tue, Sep 23, 2014 at 09:56:10AM +0200, Olaf Hering wrote:
> On Tue, Sep 23, Thomas Shao wrote:
>
> > In current hyper-v time sync service,it only gets the initial clock time
> > from the host. It didn't process the following time samples. This change
> > introduced a module parameter called host_time_sync. If it is set to true,
> > the guest will periodically sychronize it's time with the host clock using
> > host time sample. By default it is disabled, because we still recommend
> > user to configure NTP for time synchronization.

You [Microsoft?] do? Can you link to public sources where is this stated
please? I don't see any mention of doing this on
http://technet.microsoft.com/en-us/library/dn720239.aspx .. The only
official Microsoft information with respect to Hyper-V guest time
synchronisation I've seen has been for Windows guests but perhaps I've
looked in the wrong places.

The reason I ask is because regular ntpd is not enough to discipline a
Linux Hyper-V guest's clock. So much drift can occur under load that
ntpd can't bring the clock under sync. For now, I've been using Chrony
which has a higher tolerance for correcting drifting clocks. I'm not the
only one seeing this either (see http://serverfault.com/a/488528/203726
and
http://serverfault.com/questions/523389/linux-clock-loses-10-minutes-every-week
).

It would be good to something official about this issue as it is painful
when happens.

--
Sitsofe | http://sucs.org/~sits/


\
 
 \ /
  Last update: 2014-09-25 08:41    [W:0.437 / U:0.140 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site