Yo Richard!
On Sun, 22 Feb 2015 15:05:48 +0100
Richard Cochran <[email protected]> wrote:
> > I'm getting 5 uSec jitter between one hardware timing host and one
> > software time host.
>
> Sounds about right, actually pretty good. Adding a CPU and/or network
> load should make it worse.
Yup, I clearly see that, nothing worse then 7 uSec yet.
> Regarding wifi, does it say "software-transmit" as well as
> "software-receive", or software-receive only?
No. I noticed how the Redhat HOWTO specifies all three needed. That
should be in the linuxptp README.
> PTP doesn't work well anyhow over wifi because of the unpredicable
> transmission scheme.
Can it be worse than just plain old NTP?
> The newer wireless protocol actually includes a
> ptp-like synchronization scheme, but I am not aware of any hardware or
> software implementations.
Interesting...
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
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...
Not sure what to do now. I wish there was a -l 8 to output the
automatic settings.
I looked at doing manual settings and go confused. Like what to set
for -M? Same as ptp4l or unique? Got my system clock off by 24 hours
and gave up...
BTW, here is what my ethtool says:
kong ~ # ethtool -T eth0
Time stamping parameters for eth0:
Capabilities:
hardware-transmit (SOF_TIMESTAMPING_TX_HARDWARE)
software-transmit (SOF_TIMESTAMPING_TX_SOFTWARE)
hardware-receive (SOF_TIMESTAMPING_RX_HARDWARE)
software-receive (SOF_TIMESTAMPING_RX_SOFTWARE)
software-system-clock (SOF_TIMESTAMPING_SOFTWARE)
hardware-raw-clock (SOF_TIMESTAMPING_RAW_HARDWARE)
PTP Hardware Clock: 0
Hardware Transmit Timestamp Modes:
off (HWTSTAMP_TX_OFF)
on (HWTSTAMP_TX_ON)
Hardware Receive Filter Modes:
none (HWTSTAMP_FILTER_NONE)
all (HWTSTAMP_FILTER_ALL)
ptpv1-l4-sync (HWTSTAMP_FILTER_PTP_V1_L4_SYNC)
ptpv1-l4-delay-req (HWTSTAMP_FILTER_PTP_V1_L4_DELAY_REQ)
ptpv2-l4-sync (HWTSTAMP_FILTER_PTP_V2_L4_SYNC)
ptpv2-l4-delay-req (HWTSTAMP_FILTER_PTP_V2_L4_DELAY_REQ)
ptpv2-l2-sync (HWTSTAMP_FILTER_PTP_V2_L2_SYNC)
ptpv2-l2-delay-req (HWTSTAMP_FILTER_PTP_V2_L2_DELAY_REQ)
ptpv2-event (HWTSTAMP_FILTER_PTP_V2_EVENT)
ptpv2-sync (HWTSTAMP_FILTER_PTP_V2_SYNC)
ptpv2-delay-req (HWTSTAMP_FILTER_PTP_V2_DELAY_REQ)
RGDS
GARY
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[email protected] Tel:+1(541)382-8588
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