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Date: Sat, 13 Jun 2026 14:57:45 -0700
From: Jakub Kicinski <kuba@kernel.org>
To: Nicolai Buchwitz <nb@tipi-net.de>
Cc: Doug Berger <opendmb@gmail.com>, Florian Fainelli
 <florian.fainelli@broadcom.com>, bcm-kernel-feedback-list@broadcom.com,
 Andrew Lunn <andrew+netdev@lunn.ch>, "David S . Miller"
 <davem@davemloft.net>, Eric Dumazet <edumazet@google.com>, Paolo Abeni
 <pabeni@redhat.com>, Justin Chen <justin.chen@broadcom.com>, Ovidiu Panait
 <ovidiu.panait.rb@renesas.com>, netdev@vger.kernel.org,
 linux-kernel@vger.kernel.org
Subject: Re: [PATCH net-next 0/3] net: bcmgenet: collapse TX priority queues
Message-ID: <20260613145745.36c5403e@kernel.org>
In-Reply-To: <20260612205915.3156127-1-nb@tipi-net.de>
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On Fri, 12 Jun 2026 22:59:12 +0200 Nicolai Buchwitz wrote:
> Tested on Raspberry Pi CM4 (BCM2711):
>   - Ovidiu's reproducer (iperf3 -u -b0 -P16 -t60) no longer trips
>     NETDEV_WATCHDOG.
>   - UDP sustains 956 Mbit/s line rate over 60 s with 0 datagrams
>     lost (0/4952890).
>   - Single-stream TCP throughput unchanged at 943 Mbit/s.

Of course it has no impact on a single TCP stream test, since TCP
stream can only use one queue. If anything it should help.
The testing here is not very convincing. At least install a realistic
qdisc (fq/fq_codel/cake) and run multi-stream test with multiple cores?
What's the CPU idle delta in such a test?

The reason for this change is not coming thru from the submission.
Ovidiu's patch makes much more intuitive sense. I'll apply that,
please rebase.