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[144.49.247.13]) by smtp-relay.gmail.com with ESMTPS id 98e67ed59e1d1-3ae84587856sm626579a91.3.2026.10.29.14.30.31 for (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Thu, 29 Oct 2026 14:30:31 -0700 (PDT) X-Relaying-Domain: broadcom.com X-CFilter-Loop: Reflected Received: by mail-qk1-f197.google.com with SMTP id af79cd13be357-9440b27c1feso412347585a.2 for ; Thu, 29 Oct 2026 14:30:31 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=broadcom.com; s=google; t=1793309431; x=1793914231; darn=lists.infradead.org; h=content-transfer-encoding:content-type:in-reply-to:autocrypt:from :content-language:references:cc:to:subject:user-agent:mime-version :date:message-id:from:to:cc:subject:date:message-id:reply-to :content-type; bh=0ua09dxb/+6Ms2fbyBUf/EPsfi1o/dMsdbIpjzPkg9M=; b=akN+cJ/Y5TAwhXNArFrJN6w/VU+l7ckppwatlYQxF0LEe5bWKYMzmsxnkU70xjUetK P3emyEKI1flMcu6lmip+dHF5zG/Ie9d8QnAbS7vGyCND0lL7Ow6OVACq4lj8y/bvYqsI NtHzLf8ccimzCwCDw/E+S4m3qNM9oiBqe3iVc= X-Forwarded-Encrypted: i=1; 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charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-DetectorID-Processed: b00c1d49-9d2e-4205-b15f-d015386d3d5e X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20261029_143033_894436_CE035EA0 X-CRM114-Status: GOOD ( 10.99 ) X-Spam-Score: -2.1 (--) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" X-Spam-Status: No, score=-12.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=4.0.1 X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 On 10/16/26 05:18, 'Eugen Hristev' via BCM-KERNEL-FEEDBACK-LIST,PDL wrote: > Limit each iProc MSI parent IRQ to 16 event-queue entries. > > A continuously fed queue could otherwise keep the chained handler running > and starve other work. The budget still drains pending events and lets the > next parent interrupt continue processing, improving fairness and bounding > interrupt-handler latency. > > Without this starvation avoidance, one CPU can stall indefinitely > in the loop and not serve other interrupts, timers, etc. > > While testing it with an Ethernet NIC, when too many MSI interrupts > come in, CPU might get starved: > > Connecting to host 192.168.30.1, port 5201 > [ 5] local 192.168.30.2 port 52586 connected to 192.168.30.1 port 5201 > [ ID] Interval Transfer Bitrate Retr Cwnd > [ 5] 0.00-1.00 sec 240 MBytes 2.01 Gbits/sec 2 334 KBytes > [ 5] 1.00-2.00 sec 63.2 MBytes 531 Mbits/sec 1 1.41 KBytes > [ 5] 2.00-3.00 sec 0.00 Bytes 0.00 bits/sec 0 1.41 KBytes > [ 5] 3.00-4.00 sec 0.00 Bytes 0.00 bits/sec 0 1.41 KBytes > [ 5] 4.00-5.00 sec 0.00 Bytes 0.00 bits/sec 0 1.41 KBytes > [ 5] 5.00-6.00 sec 0.00 Bytes 0.00 bits/sec 0 1.41 KBytes > [ 5] 6.00-7.00 sec 0.00 Bytes 0.00 bits/sec 0 1.41 KBytes > [ 5] 7.00-8.00 sec 0.00 Bytes 0.00 bits/sec 0 1.41 KBytes > [ 5] 8.00-9.00 sec 0.00 Bytes 0.00 bits/sec 0 1.41 KBytes > [ 177.568497] rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: > [ 177.568913] rcu: 0-...!: (1 GPs behind) idle=28ac/1/0x4000000000000002 softirq=28922/28930 fqs=1 > [ 177.569457] rcu: (detected by 1, t=5256 jiffies, g=21629, q=819 ncpus=4) > [ 177.569870] Sending NMI from CPU 1 to CPUs 0: > > With this bounded approach, IRQ handler will complete and continue > to serve MSI events on the next handler invocation. > > Assisted-by: Github Copilot > Signed-off-by: Eugen Hristev Reviewed-by: Florian Fainelli -- Florian