Yo Richard!
On Mon, 23 Feb 2015 09:50:43 +0100
Richard Cochran <richardcoch...@gmail.com> wrote:
> > > PTP doesn't work well anyhow over wifi because of the unpredicable
> > > transmission scheme.
> >
> > Can it be worse than just plain old NTP?
>
> I would think it can, depending on the PI weights.
Ouch... But I guess pure theory until a WiFi driver has real support.
> > Sadly no luck getting phc2sys to work for me on a system already
> > running ptp4l. I change time_stamping software to hardware and run
> > this:
> >
> > kong ~ # phc2sys -a -m -l 7
>
> This would be without ntpshm.
Odd, so automatic configuration not so automatic. I told ptp4l to
use ntpshm, that should be passed along.
> > phc2sys[880.851]: PI servo: sync interval 1.000 kp 0.700 ki 0.300000
> > phc2sys[881.852]: reconfiguring after port state change
> > phc2sys[881.852]: master clock not ready, waiting...
>
> For a simple run without ntpshm, try this:
>
> phc2sys -a -r -i eth0 -m -q
That fails more than one way:
kong ~ # phc2sys -a -r -i eth0 -m -q
'-i' has been deprecated. please use '-s' instead.
autoconfiguration cannot be mixed with manual config options.
> > I looked at doing manual settings and go confused. Like what to set
> > for -M? Same as ptp4l or unique?
>
> So, backing up a bit, when using hardware time stamping, the ptp4l
> servo should never be set to ntpshm. That is only for software time
> stamping.
That seems odd. It is standard to run chronyd with input from NMEA
(software) time and PPS (hardware) time. Makes it easy to see the
quality of each.
So what, backing up more, should my ptp4l be set to?
Here is my config:
kong ~ # cat /usr/local/etc/ptp4l.conf
[global]
# free_running 1
summary_interval 10
time_stamping software
clock_servo ntpshm
ntpshm_segment 2
[eth0]
> For a HW time stamping setup, I would run ptp4l with defaults,
Which will not start for me:
kong ~ # ptp4l
no interface specified
But this works:
kong ~ # ptp4l -i eth0 &
> and
> then phc2sys like so.
>
> phc2sys -s eth0 -E ntpshm -m -q
>
> The -M value only has to agree with your ntp setup.
Which also fails instantly for me:
kong ~ # phc2sys -s eth0 -E ntpshm -m -q -M 2
time offset must be specified using -w or -O
This works, but is off by a mere 4,000 Seconds!
kong ~ # ptp4l -i eth0 &
kong ~ # phc2sys -s eth0 -E ntpshm -m -q -M 2 -w
phc2sys[82492.705]: phc offset -59931 s0 freq +0 delay 1580
phc2sys[82493.705]: phc offset -58092 s0 freq +0 delay 1509
phc2sys[82494.705]: phc offset -56906 s0 freq +0 delay 1516
phc2sys[82495.705]: phc offset -56815 s0 freq +0 delay 1516
phc2sys[82496.705]: phc offset -56684 s0 freq +0 delay 1517
phc2sys[82497.705]: phc offset -70368744234187 s0 freq +0 delay 1516
phc2sys[82498.706]: phc offset -70368744232479 s0 freq +0 delay 1517
phc2sys[82499.706]: phc offset -140737488408265 s0 freq +0 delay 1516
phc2sys[82500.706]: phc offset -140737488408179 s0 freq +0 delay 1516
Way crazy!
> I admit the options for phc2sys are really confusing. On the one
> hand, the phc2sys underwent a "organic" development process, and on
> the other hand, there really are a great many ways to configure the
> system clock and one (or more!) PTP hardware clocks. I always have to
> re-read the man page every time.
Which is why I am working on this:
http://www.catb.org/gpsd/gpsd-time-service-howto.html
And another reason we are trying to come up with an improved SHM
protocol on gpsd-dev and ntpd-dev. Way too easy for two servers
to clobber one shmid.
Any reason not to merge ptp4l and phc2sys?
And another cesspool is pmc. I see it makes a nice low level tool, but
time for a simple way to use it like 'pmc -a' and 'pmc -A' which would
dump all possible data in short and long form, like 'hdparm -i' and
'hdparm -I' do for disks.
RGDS
GARY
---------------------------------------------------------------------------
Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97701
g...@rellim.com Tel:+1(541)382-8588
------------------------------------------------------------------------------
Download BIRT iHub F-Type - The Free Enterprise-Grade BIRT Server
from Actuate! Instantly Supercharge Your Business Reports and Dashboards
with Interactivity, Sharing, Native Excel Exports, App Integration & more
Get technology previously reserved for billion-dollar corporations, FREE
http://pubads.g.doubleclick.net/gampad/clk?id=190641631&iu=/4140/ostg.clktrk
_______________________________________________
Linuxptp-devel mailing list
Linuxptp-devel@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/linuxptp-devel
