On Wed, May 09, 2018 at 04:05:48PM +0000, Keller, Jacob E wrote:
> > Delay responses don't generate TX timestamps (unlike NSM responses).
> > How can a high rate of RX timestamps cause a TX timestamp to be
> > missed? Is this a common HW limitation? I see this happening with
> > three different drivers (tg3, igb, ixgbe).
> >
>
> I'm not aware of such a limitation... Is it possible that it's fast enough
> that the general latency in the system exceeds the polling timeout? What
> about if you increase the timeout window when waiting for the timestamp
> response?
I tried increasing the timeout to 1000 milliseconds and it made no
difference.
> For the Intel parts, they should share a common tx_hwtstamp_skipped or
> tx_hwtstamp_missed counters in ethtool -S which should indicate if the driver
> thinks timestamps are being missed.
Thanks for the hints.
# ethtool -S enp2s0f0 | grep skip
tx_hwtstamp_skipped: 0
I tried it again with ptp4l using SW timestamping and it's the same
problem appearing at the same rate of requests. Does that mean that
the error queue cannot accept a single packet because the buffers are
full due to the non-error queue?
--
Miroslav Lichvar
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