From: Richard Cochran <richardcochran@gmail.com>
To: Thomas Shao <huishao@microsoft.com>
Cc: "tglx@linutronix.de" <tglx@linutronix.de>,
"gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"devel@linuxdriverproject.org" <devel@linuxdriverproject.org>,
"olaf@aepfle.de" <olaf@aepfle.de>,
"apw@canonical.com" <apw@canonical.com>,
"jasowang@redhat.com" <jasowang@redhat.com>,
KY Srinivasan <kys@microsoft.com>
Subject: Re: [PATCH 2/2] hyperv: Implement Time Synchronization using host time sample
Date: Tue, 14 Oct 2014 15:19:35 +0200 [thread overview]
Message-ID: <20141014131935.GA5994@localhost.localdomain> (raw)
In-Reply-To: <CD2CABCB2C0A0D4682C5F8AD840141540BFD41@HKXPRD3002MB006.064d.mgd.msft.net>
On Tue, Oct 14, 2014 at 01:04:35PM +0000, Thomas Shao wrote:
> > > + /*
> > > + * Use the Hyper-V time sample to adjust the guest time. The
> > > + * algorithm is: If the sample offsets exceeds 1 second, we
> > > + * directly set the clock to the server time. If the offset is
> >
> > So the guests will experience random time jumps in the kernel, without any
> > rhyme or reason?
>
> This behavior is designed for some extreme cases. Like manually setting guest time
> to some value. Or the host resumes from a hibernate state. Normally, we should not
> run into this.
But when it *does* happen, the guest software will have no way of
knowing what happened. That stinks.
Taking your example, when the guest sets its time, the time will
suddenly jump somewhere else, and for no apparent reason.
>From the guest's point of view, this is really not acceptable.
Thanks,
Richard
next prev parent reply other threads:[~2014-10-14 13:19 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-10-14 11:11 [PATCH 2/2] hyperv: Implement Time Synchronization using host time sample Thomas Shao
2014-10-14 11:19 ` Dan Carpenter
2014-10-14 12:50 ` Thomas Shao
2014-10-14 13:10 ` Dan Carpenter
2014-10-14 13:13 ` Thomas Shao
2014-10-14 13:16 ` Mike Surcouf
2014-10-14 14:00 ` Thomas Shao
2014-10-14 16:46 ` Mike Surcouf
2014-10-14 14:21 ` Richard Cochran
2014-10-14 13:43 ` Joe Perches
2014-10-14 11:54 ` Richard Cochran
2014-10-14 13:04 ` Thomas Shao
2014-10-14 13:19 ` Richard Cochran [this message]
2014-10-14 14:08 ` Thomas Shao
2014-10-14 13:25 ` Richard Cochran
2014-10-14 14:12 ` Thomas Shao
2014-10-14 14:14 ` Mike Surcouf
2014-10-14 14:33 ` Richard Cochran
2014-10-14 15:00 ` Victor Miasnikov
2014-10-14 16:30 ` Richard Cochran
2014-10-14 14:25 ` Richard Cochran
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20141014131935.GA5994@localhost.localdomain \
--to=richardcochran@gmail.com \
--cc=apw@canonical.com \
--cc=devel@linuxdriverproject.org \
--cc=gregkh@linuxfoundation.org \
--cc=huishao@microsoft.com \
--cc=jasowang@redhat.com \
--cc=kys@microsoft.com \
--cc=linux-kernel@vger.kernel.org \
--cc=olaf@aepfle.de \
--cc=tglx@linutronix.de \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox