netdev - Re: [PATCH net-next v2 1/2] qed: Add infrastructure for PTP support.

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Message-ID: <BL2PR07MB2306F664F2BB20FB5768A2798D4B0@BL2PR07MB2306.namprd07.prod.outlook.com>
Date:   Mon, 30 Jan 2017 18:00:46 +0000
From:   "Mintz, Yuval" <Yuval.Mintz@...ium.com>
To:     Richard Cochran <richardcochran@...il.com>
CC:     "davem@...emloft.net" <davem@...emloft.net>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "Kalluru, Sudarsana" <Sudarsana.Kalluru@...ium.com>
Subject: Re: [PATCH net-next v2 1/2] qed: Add infrastructure for PTP support.

> > I might have gotten it all wrong, but I was under the assumption that time-
> > stamped packets are periodic, and that the interval between two isn't
> > going to be so small.

> That is an incorrect assumption.  Consider the Delay_Req packets
> arriving on a port in the MASTER state.

Right; I was ignore that, thinking only on the clients.

> > Is so, how does having a couple of additional instructions in between
> > jeopardizes the next time stamp?

> It is not just about the few instructions, but there is also
> preemption possible.

I believe qede would only call this under spinlock, so that's probably
not an issue.
Regardless, that's no reason not to change the behavior.

Thanks.