From: Kurt Kanzenbach <kurt@linutronix.de>
To: Vladimir Oltean <vladimir.oltean@nxp.com>
Cc: netdev@vger.kernel.org, "David S. Miller" <davem@davemloft.net>,
Eric Dumazet <edumazet@google.com>,
Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
Jamal Hadi Salim <jhs@mojatatu.com>,
Cong Wang <xiyou.wangcong@gmail.com>,
Jiri Pirko <jiri@resnulli.us>,
Vinicius Costa Gomes <vinicius.gomes@intel.com>,
Gerhard Engleder <gerhard@engleder-embedded.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH net-next 3/3] net/sched: taprio: dynamic max_sdu larger than the max_mtu is unlimited
Date: Thu, 16 Feb 2023 11:34:33 +0100 [thread overview]
Message-ID: <875yc1q4p2.fsf@kurt> (raw)
In-Reply-To: <20230216102914.wat37qsih5xx3wk4@skbuf>
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On Thu Feb 16 2023, Vladimir Oltean wrote:
> On Thu, Feb 16, 2023 at 10:28:48AM +0100, Kurt Kanzenbach wrote:
>> On Thu Feb 16 2023, Vladimir Oltean wrote:
>> > It makes no sense to keep randomly large max_sdu values, especially if
>> > larger than the device's max_mtu. These are visible in "tc qdisc show".
>> > Such a max_sdu is practically unlimited and will cause no packets for
>> > that traffic class to be dropped on enqueue.
>> >
>> > Just set max_sdu_dynamic to U32_MAX, which in the logic below causes
>> > taprio to save a max_frm_len of U32_MAX and a max_sdu presented to user
>> > space of 0 (unlimited).
>> >
>> > Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
>>
>> Doesn't this deserve a Fixes tag as well?
>
> No, I don't think so. It's just so that the user (and later, the offloading
> driver) doesn't see arbitrarily large values, just a simplifying 0.
Yes, exactly. It's visible by the user.
> I guess it could potentially make a difference to the software taprio
> data path with TSO, if the max MTU is comparable with the segment
> sizes.
>
> Anyway, with or without the Fixes tag, the patch lands in the same place.
Yup. It doesn't really matter that much.
Reviewed-by: Kurt Kanzenbach <kurt@linutronix.de>
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next prev parent reply other threads:[~2023-02-16 10:40 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-02-15 22:46 [PATCH net-next 0/3] taprio queueMaxSDU fixes Vladimir Oltean
2023-02-15 22:46 ` [PATCH net-next 1/3] net/sched: taprio: fix calculation of maximum gate durations Vladimir Oltean
2023-02-16 9:27 ` Kurt Kanzenbach
2023-02-15 22:46 ` [PATCH net-next 2/3] net/sched: taprio: don't allow dynamic max_sdu to go negative after stab adjustment Vladimir Oltean
2023-02-16 9:27 ` Kurt Kanzenbach
2023-02-15 22:46 ` [PATCH net-next 3/3] net/sched: taprio: dynamic max_sdu larger than the max_mtu is unlimited Vladimir Oltean
2023-02-16 9:28 ` Kurt Kanzenbach
2023-02-16 10:29 ` Vladimir Oltean
2023-02-16 10:34 ` Kurt Kanzenbach [this message]
2023-02-16 10:35 ` Vladimir Oltean
2023-02-20 8:00 ` [PATCH net-next 0/3] taprio queueMaxSDU fixes patchwork-bot+netdevbpf
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