Re: [Linuxptp-users] poll tx timestamp timeout

[Richard C. <ric...@gm...>]

On Tue, Aug 13, 2013 at 05:15:05PM -0700, David Gravereaux wrote:
> I've been running ptp4l as a master, and this cropped-up a few times in
> the log last night.

You are running your i210 as master with P2P, right?

What are you using for logSyncInterval and logMinPdelayReqInterval?

How often does this occur? Twice in twelve hours?

Which messages are affected, sync, peer delay request, or both?

> I've increased 'tx_timestamp_timeout' to 10ms, but has happened a few
> more times even when run with an increased priority such as:
> 
>   sudo nice -n -19 ptp4l -i eth2 -f gPTP.cfg

Changing the priority of ptp4l will have no effect (see below).

> Could this be igb.ko slow on the up-take?

When the i210 time stamps a transmitted event packet, it generates an
interrupt. The ISR then schedules a work callback which runs after the
next system tick.* The callback then delivers the time stamp to the
error queue of the process's socket.

* [Make sure tx_timestamp_timeout is long enough to account for this.]

Although the i210 can only handle one outstanding Tx time stamp, still
I don't see how any can go missing, since the ptp4l program always
waits for Tx time stamp before sending another event message.

I can think of two explanations.

1. The i210 simply fails to time stamp some event packets.
2. You are running a second program that generates event packets.

Thanks,
Richard