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Subject: Re: [EXT] Re: [v1,net-next, 1/2] ethtool: add setting frame preemption of traffic classes
From:   Andre Guedes <andre.guedes@linux.intel.com>
Cc:     Ivan Khoronzhuk <ivan.khoronzhuk@linaro.org>,
        Murali Karicheri <m-karicheri2@ti.com>,
        Vinicius Costa Gomes <vinicius.gomes@intel.com>,
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        "saeedm@mellanox.com" <saeedm@mellanox.com>,
        "tglx@linutronix.de" <tglx@linutronix.de>,
        Vladimir Oltean <vladimir.oltean@nxp.com>,
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        Claudiu Manoil <claudiu.manoil@nxp.com>,
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To:     Vladimir Oltean <olteanv@gmail.com>
Message-ID: <157868996635.61655.11306531040262384025@aguedesl-mac01.jf.intel.com>
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Date:   Fri, 10 Jan 2020 12:59:26 -0800
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Hi Vladimir,

Quoting Vladimir Oltean (2020-01-10 08:02:45)
> > I'm not sure about the knob 'timers (hold/release)' described in the quotes
> > above. I couldn't find a match in the specs. If it refers to 'holdAdvance' and
> > 'releaseAdvance' parameters described in 802.1Q-2018, I believe they are not
> > configurable. Do we know any hardware where they are configurable?
> >
> 
> On NXP LS1028A, HOLD_ADVANCE is configurable on both ENETC and the
> Felix switch (its default value is 127 bytes). Same as Synopsys, it is
> a global setting and not per queue or per GCL entry.
> RELEASE_ADVANCE is not configurable.
> Regardless, I am not sure if there is any value in configuring this
> knob. Remember that the minimum guard band size still needs to be
> twice as large as the minimum Ethernet frame size.

Not adding this knob now sounds reasonable to me too, but let's consider it in
the design so we can easily add it later, in case we need it.

Regards,

Andre