netdev - Re: [PATCH net-next v1 0/9] ethtool: Add support for frame preemption

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Message-ID: <20201205095021.36e1a24d@kicinski-fedora-pc1c0hjn.DHCP.thefacebook.com>
Date:   Sat, 5 Dec 2020 09:50:21 -0800
From:   Jakub Kicinski <kuba@...nel.org>
To:     Vinicius Costa Gomes <vinicius.gomes@...el.com>
Cc:     netdev@...r.kernel.org, jhs@...atatu.com, xiyou.wangcong@...il.com,
        jiri@...nulli.us, m-karicheri2@...com, vladimir.oltean@....com,
        Jose.Abreu@...opsys.com, po.liu@....com,
        intel-wired-lan@...ts.osuosl.org, anthony.l.nguyen@...el.com
Subject: Re: [PATCH net-next v1 0/9] ethtool: Add support for frame
 preemption

On Tue,  1 Dec 2020 20:53:16 -0800 Vinicius Costa Gomes wrote:
> $ tc qdisc replace dev $IFACE parent root handle 100 taprio \
>       num_tc 3 \
>       map 2 2 1 0 2 2 2 2 2 2 2 2 2 2 2 2 \
>       queues 1@0 1@1 2@2 \
>       base-time $BASE_TIME \
>       sched-entry S 0f 10000000 \
>       preempt 1110 \
>       flags 0x2 
> 
> The "preempt" parameter is the only difference, it configures which
> queues are marked as preemptible, in this example, queue 0 is marked
> as "not preemptible", so it is express, the rest of the four queues
> are preemptible.

Does it make more sense for the individual queues to be preemptible 
or not, or is it better controlled at traffic class level?
I was looking at patch 2, and 32 queues isn't that many these days..
We either need a larger type there or configure this based on classes.