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client-ip=165.204.84.17; helo=SATLEXMB04.amd.com; pr=C Received: from SATLEXMB04.amd.com (165.204.84.17) by DS2PEPF00003445.mail.protection.outlook.com (10.167.17.72) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.20.9094.14 via Frontend Transport; Thu, 4 Sep 2025 08:26:53 +0000 Received: from SATLEXMB04.amd.com (10.181.40.145) by SATLEXMB04.amd.com (10.181.40.145) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.39; Thu, 4 Sep 2025 03:26:49 -0500 Received: from [10.85.34.65] (10.180.168.240) by SATLEXMB04.amd.com (10.181.40.145) with Microsoft SMTP Server id 15.1.2507.39 via Frontend Transport; Thu, 4 Sep 2025 03:26:44 -0500 Message-ID: <91b75418-c836-4098-9f7e-4b287598a1d7@amd.com> Date: Thu, 4 Sep 2025 13:56:38 +0530 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 3/5] sched/fair: Switch to task based throttle model To: "Bezdeka, Florian" , "ziqianlu@bytedance.com" CC: "liusongtang@bytedance.com" , "dietmar.eggemann@arm.com" , "zhouchuyi@bytedance.com" , "bigeasy@linutronix.de" , "mgorman@suse.de" , "Kiszka, Jan" , "vincent.guittot@linaro.org" , "chengming.zhou@linux.dev" , "mingo@redhat.com" , "rostedt@goodmis.org" , "joshdon@google.com" , "vschneid@redhat.com" , "xii@google.com" , "linux-kernel@vger.kernel.org" , "peterz@infradead.org" , "bsegall@google.com" , "juri.lelli@redhat.com" References: <20250808101330.GA75@bytedance> <20250812084828.GA52@bytedance> <20250815092910.GA33@bytedance> <20250822110701.GB289@bytedance> <20250903071410.GA42@bytedance> <2b2e91e7-0514-4728-a3a3-96282a0d4286@amd.com> <20250903101102.GB42@bytedance> <13467b08-96a6-478d-bb97-060b7d8887e4@amd.com> <20250903113551.GC42@bytedance> Content-Language: en-US From: K Prateek Nayak In-Reply-To: Content-Type: text/plain; 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X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 04 Sep 2025 08:26:53.0189 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 8fbcee9a-d664-43c3-6949-08ddeb8ccd6e X-MS-Exchange-CrossTenant-Id: 3dd8961f-e488-4e60-8e11-a82d994e183d X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=3dd8961f-e488-4e60-8e11-a82d994e183d;Ip=[165.204.84.17];Helo=[SATLEXMB04.amd.com] X-MS-Exchange-CrossTenant-AuthSource: DS2PEPF00003445.namprd04.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: MW5PR12MB5652 Hello Florian, On 9/4/2025 1:03 PM, Bezdeka, Florian wrote: > Hi Aaron, > > On Wed, 2025-09-03 at 19:35 +0800, Aaron Lu wrote: >> >>> [..snip..] >>>> >> >> Just want to add that with the above diff applied, I also tested >> songtang's stress test[0] and Jan's rt deadlock reproducer[1] and didn't >> see any problem. > > Thanks a lot for taking the reproducer into account. But: To trigger > PREEMPT_RT needs to be enabled, otherwise the rwlock in the epoll > infrastructure (that we highly stress) won't sleep. Just to be sure: > PREEMPT_RT was enabled on your end? I've too tested this series with Jan's reproducer on PREEMPT_RT and can confirm no hang was triggered over a full weekend run lasting more than 72Hrs with Aaron's changes applied on top of v6.16-rc6 based kernel. > >> >> [0]: https://lore.kernel.org/lkml/20250715072218.GA304@bytedance/ >> [1]: https://lore.kernel.org/all/7483d3ae-5846-4067-b9f7-390a614ba408@siemens.com/ I used the same reproducer from [1] with small modification to run.sh to periodically move epoll-stall and epoll-stall-writer to one particular CPU and keep changing this CPU ever minute. -- Thanks and Regards, Prateek