netdev - Re: [PATCH net-next] sch_cake: Make gso-splitting configurable from userspace

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Message-Id: <20180727.133950.685244782703142670.davem@davemloft.net>
Date:   Fri, 27 Jul 2018 13:39:50 -0700 (PDT)
From:   David Miller <davem@...emloft.net>
To:     dave.taht@...il.com
Cc:     netdev@...r.kernel.org, cake@...ts.bufferbloat.net
Subject: Re: [PATCH net-next] sch_cake: Make gso-splitting configurable
 from userspace

From: Dave Taht <dave.taht@...il.com>
Date: Thu, 26 Jul 2018 19:45:09 -0700

> I expect the first part of this patch to generate no controversy,
> as being able to enable configure gso-splitting on or off in all
> use cases of cake is a goodness.
> 
> But: I expect the single line re-enabling cake's fielded default of
> always splitting gro and gso packets, in shaped or unshaped mode, back
> into packets, to reduce my email systems' hard disk inbox to a barren,
> burnt cylinder, even if it is made easy to override thusly:
> 
> tc qdisc replace dev whatever root cake no-split-gso
> 
> While I agree that gro/gso is needed at 10gigE+ speeds, I feel
> offering an option to disable splitting to those users trying to run
> cake at those speeds is better than the alternative of forcing users
> running at 1Gbit, 100mbit, 10mbit and below, with and without pause
> frames, shaped or unshaped, to remember to split-gso.
> 
> While I have assembled tons of data in use cases ranging from nearly 0
> to a gbit, the first, and most compelling argument I can make is
> made in the commit that follows, where allowing GSO/GRO superpackets
> triples the size of the underlying BQL when running at a gbit.

I've applied this, we can revert it if there are strong objections.