linux-kernel - Re: [PATCH RESEND net-next 0/5] Improve the taprio qdisc's relationship with its children

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Message-ID: <20230607103001.p62au4e2cztv5xut@skbuf>
Date:   Wed, 7 Jun 2023 13:30:01 +0300
From:   Vladimir Oltean <vladimir.oltean@....com>
To:     Jamal Hadi Salim <jhs@...atatu.com>
Cc:     netdev@...r.kernel.org, "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Cong Wang <xiyou.wangcong@...il.com>,
        Jiri Pirko <jiri@...nulli.us>,
        Vinicius Costa Gomes <vinicius.gomes@...el.com>,
        linux-kernel@...r.kernel.org, intel-wired-lan@...ts.osuosl.org,
        Muhammad Husaini Zulkifli <muhammad.husaini.zulkifli@...el.com>,
        Peilin Ye <yepeilin.cs@...il.com>,
        Pedro Tammela <pctammela@...atatu.com>
Subject: Re: [PATCH RESEND net-next 0/5] Improve the taprio qdisc's
 relationship with its children

On Wed, Jun 07, 2023 at 01:09:01PM +0300, Vladimir Oltean wrote:
> That being said, a non-offloaded cbs/htb will not work with an offloaded
> taprio root anymore after commit 13511704f8d7 ("net: taprio offload:
> enforce qdisc to netdev queue mapping"), and IMO what should be done
> there is to reject somehow those child Qdiscs which also can't be
> offloaded when the root is offloaded.
> 
> Offloading a taprio qdisc (potentially with offloaded cbs children) also
> affects the autonomous forwarding data path in case of an Ethernet switch.
> So it's not just about dev_queue_xmits() from Linux.

Ah, no, I said something stupid. Non-offloaded child Qdisc should still
work with offloaded root (shaping done in software, scheduling in hardware).
I was thinking about the autonomous forwarding case in the back of my
mind, that's still problematic because the shaping wouldn't affect the
packets that Linux didn't originate.