netdev - Re: Extending socket timestamping API for NTP

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Message-ID: <20170327205807.GA11139@localhost.localdomain>
Date:   Mon, 27 Mar 2017 22:58:07 +0200
From:   Richard Cochran <richardcochran@...il.com>
To:     Denny Page <dennypage@...com>
Cc:     Miroslav Lichvar <mlichvar@...hat.com>, netdev@...r.kernel.org,
        Jiri Benc <jbenc@...hat.com>,
        "Keller, Jacob E" <jacob.e.keller@...el.com>,
        Willem de Bruijn <willemb@...gle.com>
Subject: Re: Extending socket timestamping API for NTP

On Mon, Mar 27, 2017 at 12:18:47PM -0700, Denny Page wrote:
> I think that on average, the Vendor’s numbers are likely to be more
> accurate than anyone else’s. The concept that independent software
> implementations are going to somehow obtain and maintain better
> numbers is too much of a stretch.

But you just said that Intel's first published numbers were wrong.  If
the vendors would have published accurate information, then you would
not have to have made your own measurements, and the drivers could
simply use the correct values.

Sadly, this will never happen.  The vendor's track record is 100%
fail.  The apps will always need to implement their own, truly correct
values.  Having "almost correct" values hard coded into the drivers
only makes things worse.

> FWIW, My testing indicates that the 100Mb numbers that Intel
> currently publishes are quite accurate. I don’t believe that Intel
> did the driver corrections btw, if memory serves these values were
> lifted from the Mac.

Huh?  Mac?  -ENOPARSE.

Thanks,
Richard