netdev - Re: [RFC net-next 0/5] TSN: Add qdisc-based config interfaces for traffic shapers

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Message-ID: <20170907155315.5gqy5e4susl25wa2@localhost>
Date:   Thu, 7 Sep 2017 17:53:15 +0200
From:   Richard Cochran <richardcochran@...il.com>
To:     Henrik Austad <henrik@...tad.us>
Cc:     Vinicius Costa Gomes <vinicius.gomes@...el.com>,
        netdev@...r.kernel.org, jhs@...atatu.com, xiyou.wangcong@...il.com,
        jiri@...nulli.us, intel-wired-lan@...ts.osuosl.org,
        andre.guedes@...el.com, ivan.briano@...el.com,
        jesus.sanchez-palencia@...el.com, boon.leong.ong@...el.com
Subject: Re: [RFC net-next 0/5] TSN: Add qdisc-based config interfaces for
 traffic shapers

On Thu, Sep 07, 2017 at 05:27:51PM +0200, Henrik Austad wrote:
> On Thu, Sep 07, 2017 at 02:40:18PM +0200, Richard Cochran wrote:
> And if you want to this driver to act as a bridge, how do you accomodate 
> change in network requirements? (i.e. how does this work with switchdev?)

To my understanding, this Qdisc idea provides QoS for the host's
transmitted traffic, and nothing more.

> - Or am I overthinking this?

Being able to configure the external ports of a switchdev is probably
a nice feature, but that is another story.  (But maybe I misunderstood
the authors' intent!)

> If you have more than 1 application in userspace that wants to send data 
> using this scheduler, how do you ensure fair transmission of frames? (both 
> how much bandwidth they use,

There are many ways to handle this, and we shouldn't put any of that
policy into the kernel.  For example, there might be a monolithic
application with configurable threads, or an allocation server that
grants bandwidth to applications via IPC, or a multiplexing stream
server like jack, pulse, etc, and so on...

> but also ordering of frames from each application)

Not sure what you mean by this.

> Do you expect all of this to be handled in userspace?

Yes, I do.

Thanks,
Richard