[ntp:questions] frequency adjusting only

maxime louvel m.louvel at gmail.com
Wed Apr 30 17:43:44 UTC 2008


On Wed, Apr 30, 2008 at 6:19 PM, Bill Unruh <unruh at physics.ubc.ca> wrote:

> m.louvel at gmail.com (maxime louvel) writes:
>
> >On Tue, Apr 29, 2008 at 6:27 PM, Unruh <unruh-spam at physics.ubc.ca> wrote:
>
> >> m.louvel at gmail.com (maxime louvel) writes:
> >>
> >> >Hi,
> >>
> >> >I have know run a lot of tests.
> >> >Just to let you know what I've got so far.
> >> >I have tried NTP, and NTP + PTP (Precision Time Protocol).
> >> >I haven't tried Chrony nor TSClock.
> >> >I have used the software only implementation of PTP (ptpd).
> >>
> >> >With NTP only I have got an accuracy around 1ms,
>
> Actually, I have no idea what the difference is between the "software
> implimentation" of PTP and standard NTP is. The advantage of PTP is the
> HARDWARE timestamping of the packets as they come into the ethernet card
> (special purpose ethernet cards with clocks on board) and possibly PTP
> aware switches which race through the PTP packets without delay.
>  Software only means
> that PTP uses exactly the same kernel routines, etc. to read the computer
> clock as does ntp I assume. I cannot see how it can be better unless there
> are some
> severe bugs in NTP.
> What version of NTP are you running?
>

I have  get the last tar  archive from the ntp website, and compiled it.
PTPd is a software only implementation which try to manage as it can without
hardware.
You get less accuracy than normal PTP, but still it's not so bad.


>
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