> -----Original Message----- > From: Sitsofe Wheeler [mailto:sitsofe@xxxxxxxxx] > Sent: Thursday, September 25, 2014 2:08 PM > To: Olaf Hering > Cc: Thomas Shao; gregkh@xxxxxxxxxxxxxxxxxxx; linux- > kernel@xxxxxxxxxxxxxxx; driverdev-devel@xxxxxxxxxxxxxxxxxxxxxx; > apw@xxxxxxxxxxxxx; jasowang@xxxxxxxxxx; KY Srinivasan; Haiyang Zhang > Subject: Re: [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. > Hi Sitsofe, As far as I know, currently the document about time sync in Hyper-V is only for Windows. Below is a doc from MSDN: http://blogs.msdn.com/b/virtual_pc_guy/archive/2010/11/19/time-synchronization-in-hyper-v.aspx We are working on the document about Time Sync on Hyper-V to cover both Linux and Windows. > -- > Sitsofe | http://sucs.org/~sits/ _______________________________________________ devel mailing list devel@xxxxxxxxxxxxxxxxxxxxxx http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel
