> -----Original Message-----
> From: Keller, Jacob E
> Sent: Thursday, June 17, 2021 5:04 PM
> To: 'Dale Smith' <dalepsm...@gmail.com>; Joseph Matan
> <joseph.matan...@gmail.com>
> Cc: linuxptp-users@lists.sourceforge.net
> Subject: RE: [Linuxptp-users] Intel NICs PTP Performance Comparison
>
>
>
> > -----Original Message-----
> > From: Dale Smith <dalepsm...@gmail.com>
> > Sent: Thursday, June 17, 2021 3:04 PM
> > To: Joseph Matan <joseph.matan...@gmail.com>
> > Cc: linuxptp-users@lists.sourceforge.net
> > Subject: Re: [Linuxptp-users] Intel NICs PTP Performance Comparison
> >
> > So how in the would could *more* traffic cause a *smaller* delay?
> >
>
> EEE low power ethernet kicking in, which puts the device into a low power
> state
> that has a higher latency to wake up. You could check "ethtool --show-eee" to
> see
> if the device supports it and what the status is.
>
I missed that you ruled out EEE already. I wonder if i218 supports it without
supporting the options to disable it though.... I'm not certain.
Thanks,
Jake
> > Very curious.
> >
> > Wild Guess, maybe interrupt coalescing is going on, and with more
> > packets, it's actually responding sooner?
>
> This is unlikely, since timestamps are captured in hardware, so I don't think
> it
> should impact the latency with regards to the actual timestamps.
>
> >
> > Another guess, that somehow the determination of the timestamps are
> > just plain wrong. Like maybe they were fudged to some value while
> > under heavy load, and are way more off when under light load?
> >
>
> I don't think this is the case for Intel devices.
>
> > Just guesses as I said. I don't do 1588 much anymore, but this is
> > very intriguing. Please report back if you ever get to the bottom of
> > this.
> >
> > -Dale
> >
> >
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> > Linuxptp-users@lists.sourceforge.net
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