> -----Original Message----- > From: linux-kernel-owner@xxxxxxxxxxxxxxx > [mailto:linux-kernel-owner@xxxxxxxxxxxxxxx] On Behalf Of Sitsofe Wheeler > Sent: Thursday, September 25, 2014 9:28 PM > To: Thomas Shao > Cc: Olaf Hering; gregkh@xxxxxxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; > driverdev-devel@xxxxxxxxxxxxxxxxxxxxxx; apw@xxxxxxxxxxxxx; > jasowang@xxxxxxxxxx; KY Srinivasan; Haiyang Zhang > Subject: Re: Time keeps on slipping... on Hyper-V > > On Thu, Sep 25, 2014 at 09:40:42AM +0000, Thomas Shao wrote: > > > > On Tue, Sep 23, Thomas Shao wrote: > > > > > > > > with the host clock using host time sample. By default it is > > > > disabled, because we still recommend user to configure NTP for > > > > time > > > > > > -----Original Message----- > > > From: Sitsofe Wheeler [mailto:sitsofe@xxxxxxxxx] > > > Sent: Thursday, September 25, 2014 2:08 PM > > > > > > You [Microsoft?] do? Can you link to public sources where is this > > > stated > > > > 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-synchro > > nization-in-hyper-v.aspx > > That post is problematic and not quite enough because it doesn't say "we > recommend you always configure an external time source for a guest" but > rather gives a more complicated statement saying "because guest time drifts > we have a time synchronisation service that will sort things out. > If you happen to be running a domain controller we recommend you configure > regular synchronisation to an external time source in addition". This leads to > questions like: if my (Linux) guest's sole purpose is to run a web server am I in > the domain controller situation (domain controllers have to re-serve time so > perhaps they are special)? > It also doesn't cover the "clock drift is so bad ntpd can't correct it" > issue. > > Have you seen this document on TechNet - > http://blogs.technet.com/b/enterprise_admin/archive/2010/04/04/linux-on-hy > per-v-timesync.aspx > "With the new Integration Services, Linux virtual machines can! > > TimeSync means that you don’t have to hassle with configur[ing] > network-based time sync for your Linux VMs on Hyper-V…they can get the > correct time from the host!" > > This document gives simpler advice looks quite compelling at first glance. > > > We are working on the document about Time Sync on Hyper-V to cover > > both Linux and Windows. > > The sooner you can get such an official document out the better. All sources of > guest time synchronisation information (including Microsoft blogs and > non-Microsoft Q&A sites) need updating so they say the same > (correct!) thing in a clear way. > > For the meantime can you state what you believe the recommend practice is > for Linux Hyper-V guests with regards to time synchronisation? > We still recommend user to configure NTP in the guest VM. With the new time sync feature in this patch, you could have one more option to enable the guest-host sync, if the NTP didn't work in the environment. For example the guest VM didn't have network connection. > -- > Sitsofe | http://sucs.org/~sits/ > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the > body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at > http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ _______________________________________________ devel mailing list devel@xxxxxxxxxxxxxxxxxxxxxx http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel
