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Sat, 10 Oct 2026 15:55:47 +0000 Date: Sat, 10 Oct 2026 23:42:41 +0800 From: Chen Yu To: Vincent Guittot CC: , , , , , , , , , , , , , , , , , , , , , , Subject: Re: [PATCH 07/18] sched/fair: Add push task mechanism for fair Message-ID: References: <20261002154415.2270586-1-vincent.guittot@linaro.org> <20261002154415.2270586-8-vincent.guittot@linaro.org> Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: X-ClientProxiedBy: SI2PR06CA0015.apcprd06.prod.outlook.com (2603:1096:4:186::7) To DM4PR11MB6020.namprd11.prod.outlook.com (2603:10b6:8:61::19) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: DM4PR11MB6020:EE_|CH3PR11MB566309:EE_ X-MS-Office365-Filtering-Correlation-Id: 2767d4e7-acb0-4f7c-4589-08df26e6f2eb X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|23010399003|366016|376014|1800799024|7416014|56012099006|11063799006|4143699003|22082099003|18002099003|6133799003|10067099003|261009223027099003; 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> > > > + /* > > + * Only a push triggered by cache aware scheduling will push the > > + * task towards its preferred LLC. Pushes for other reasons, like short > > + * slice task, uses the default push strategy. > > + */ > > + push_cpu = -1; > > + if (select_flags & WF_RQ_PUSH) > > + push_cpu = check_pushable_cache_task(prev_cpu, p); > > Is there any reason that you do'nt want to migrate the task at wakeup too ? > The wakeup path seems to be too fast to aggregate the tasks, so that multiple CPUs try to migrate the task to the same LLC without synchronization - a task bouncing issue was observed when cache-aware migration was enabled in the wakeup path. We can double-check in the latest kernel to see if that is still the case, and to see if we can mitigate that. thanks, Chenyu