[PATCH v4 0/2] hv_util: adjust system time smoothly

From	Vitaly Kuznetsov <vkuznets@redhat.com>
Newsgroups	linux.kernel
Subject	[PATCH v4 0/2] hv_util: adjust system time smoothly
Date	2017-01-19 15:20 +0100
Message-ID	<t1lJf-2Aj-9@gated-at.bofh.it> (permalink)
Organization	linux.* mail to news gateway

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With TimeSync version 4 protocol support we started updating system time
continuously through the whole lifetime of Hyper-V guests. Every 5 seconds
there is a time sample from the host which triggers do_settimeofday[64]().
While the time from the host is very accurate such adjustments may cause
issues:
- Time is jumping forward and backward, some applications may misbehave.
- In case an NTP server runs in parallel and uses something else for time
  sync (network, PTP,...) system time will never converge.
- Systemd starts annoying you by printing "Time has been changed" every 5
  seconds to the system log.

Instead of doing in-kernel time adjustments offload the work to an
NTP client by exposing TimeSync messages as a PTP device. Users may now
decide what they want to use as a source.

Changes since v3:
- Minor style changes [Stephen Hemminger]
- Added a comment explaining why we don't fail the driver registration
  when ptp_clock_register() fails [Thomas Gleixner]
- Add Thomas' A-b to PATCH1

Vitaly Kuznetsov (2):
  hv_util: switch to using timespec64
  hv_utils: implement Hyper-V PTP source

 drivers/hv/hv_util.c | 146 ++++++++++++++++++++++++++++++++++++++++++---------
 1 file changed, 120 insertions(+), 26 deletions(-)

-- 
2.9.3

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[PATCH v4 0/2] hv_util: adjust system time smoothly Vitaly Kuznetsov <vkuznets@redhat.com> - 2017-01-19 15:20 +0100
  [PATCH v4 2/2] hv_utils: implement Hyper-V PTP source Vitaly Kuznetsov <vkuznets@redhat.com> - 2017-01-19 15:20 +0100
    Re: [PATCH v4 2/2] hv_utils: implement Hyper-V PTP source Radim Krcmar <rkrcmar@redhat.com> - 2017-01-20 17:30 +0100
      Re: [PATCH v4 2/2] hv_utils: implement Hyper-V PTP source Vitaly Kuznetsov <vkuznets@redhat.com> - 2017-01-23 17:40 +0100
    RE: [PATCH v4 2/2] hv_utils: implement Hyper-V PTP source KY Srinivasan <kys@microsoft.com> - 2017-01-28 20:10 +0100
      Re: [PATCH v4 2/2] hv_utils: implement Hyper-V PTP source Vitaly Kuznetsov <vkuznets@redhat.com> - 2017-01-30 10:40 +0100

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