[mythtv-users] Fedora 7 clock drift

[Jerome Yuzyk]

On Monday 08 October 2007 13:42, f-myth-users at media.mit.edu wrote:
>     > Date: Mon, 08 Oct 2007 14:40:27 +0100
>     > From: Mike Perkins <mikep at randomtraveller.org.uk>
>     >
>     > Jerome Yuzyk wrote:
>     > > I am wondering if any Myth users have been seeing clock-drift with
>     > > Fedora 7. I was wondering what was going on when my evening
>     > > recordings began to start noticeably late. For years I have used
>     > > ntpdate to sync my clock at 1 minute after 4am and log the result.
>     > > On my Myth box pre-Fedora 7 the time difference was around 0 -
>     > > usually -0.7 seconds. The day I upgraded I started logging
>     > > differences of 12 seconds, every single day. I _vaguely_remember
>     > > reading something about this happening in recent kernels (when the
>     > > CPU governor is used) but no amount of Googling turns up any
>     > > similar references.
>     > >
>     > > Anyone else noticed this? I started noticing when the 11pm news
>     > > started getting about 10 seconds clipped off the front.
>     >
>     > Is ntpd an option for you? It's what I use on all my pcs.
>
> Does this persist across warm or cold boots?
>
> 12s/day is quite a high drift.  It's not -quite- more than ntpd can

These machines generally don't get rebooted so I can't say about this. And 
most are servers so I'm not going to test.

For some data points, here is the result of my survey. The w0X and technip 
machines are all IBM multi-CPU 1U or 2U slabs, and the www and web machines 
are Dell slabs. Except for tv the machines all have the release they started 
life on so that tells you how old they are, except for gate which is a P-400 
retread.


host    RedHat release                  kernel  drift (s)
----------------------------------------------------------------------------
w01     RedHat 9 (Shrike)               2.4.20  +1.3
w02     RHEL-ES 3 (Taroon)              2.4.21  +3.0
w03     RHEL-ES 4 (Nahant Update 3)     2.6.9   +1.5
w04     RHEL-ES 4 (Nahant Update 3)     2.6.9   +0.7
w05     RHEL-ES 4 (Nahant Update 3)     2.6.9    0.0
w06     RHEL-ES 4 (Nahant Update 4)     2.6.9   -0.2
www     RedHat 7.3 (Valhalla)           2.4.18  -9.5
web     Fedora Core 4 (Stentz)          2.6.11  +11.5
t01     RHEL Server 5.1 Beta (Tikanga)  2.6.18  +9.0 (only 1 week of data)

tv      Fedora 7 (prior FC 5)           2.6.22  +12.0 (-0.75)
gate    Fedora Core 1 (Yarrow)          2.4.22  -4.2
desk    Fedora Core 5 (Bordeaux)        2.6.17  -1.0