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[82.192.129.174]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-48e3ecdfd8dsm32615874f8f.56.2026.10.29.04.52.14 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 29 Oct 2026 04:52:15 -0700 (PDT) Message-ID: Date: Thu, 29 Oct 2026 12:52:13 +0100 X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2] net/sched: sch_cake: skip redundant cake_mq rate updates To: "Shubhang Kaushik (Ampere)" , =?UTF-8?Q?Toke_H=C3=B8iland-J=C3=B8rgensen?= , Jamal Hadi Salim , Jiri Pirko , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Simon Horman , =?UTF-8?Q?Jonas_K=C3=B6ppeler?= , Shubhang Kaushik , "Christoph Lameter (Ampere)" Cc: =?UTF-8?Q?Toke_H=C3=B8iland-J=C3=B8rgensen?= , cake@lists.bufferbloat.net, netdev@vger.kernel.org, linux-kernel@vger.kernel.org References: <20261026-net_sched_sch_cake-v2-1-cb1d4e6ed990@gentwo.org> Content-Language: en-US From: Paolo Abeni In-Reply-To: <20261026-net_sched_sch_cake-v2-1-cb1d4e6ed990@gentwo.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 10/27/26 05:32, Shubhang Kaushik (Ampere) wrote: > cake_mq periodically counts active child qdiscs in cake_dequeue() and > derives an effective per-child shaper rate. cake_dequeue() currently > reconfigures every tin after each scan, even when that effective rate > is unchanged. > > The dequeue-time call chain is: > > cake_dequeue() > -> cake_configure_rates(..., true) > -> cake_config_*() > -> cake_set_rate() > > With rate_adjust=true, cake_set_rate() only refreshes rate-derived > state. Tin 0 records the unscaled rate argument in every supported > CAKE tin mode, so its installed rate identifies whether this call chain > would change any state. > > Skip the reconfiguration when the effective rate is already installed, > while continuing to update the activity-sampling timestamp and > active-queue statistic. > > Fixes: 1bddd758bac2 ("net/sched: sch_cake: share shaper state across sub-instances of cake_mq") > Signed-off-by: Shubhang Kaushik (Ampere) IMHO this is borderline material for 'net'. Was any regression visible on top of 1bddd758bac2, e.g. in term of CPU usage? /P