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client-ip=58.252.5.68; helo=mail.oppo.com; pr=C Received: from mail.oppo.com (58.252.5.68) by TY2PEPF0000AB87.mail.protection.outlook.com (10.167.253.6) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.20.9073.11 via Frontend Transport; Tue, 26 Aug 2025 08:17:38 +0000 Received: from localhost.localdomain (172.16.40.118) by mailappw30.adc.com (172.16.56.197) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.57; Tue, 26 Aug 2025 16:17:37 +0800 From: xupengbo To: CC: , , , , , , , , , , , , , , Subject: Re: [PATCH v2] sched/fair: Fix unfairness caused by stalled tg_load_avg_contrib when the last task migrates out. Date: Tue, 26 Aug 2025 16:17:31 +0800 Message-ID: <20250826081731.20384-1-xupengbo@oppo.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20250826075743.19106-1-xupengbo@oppo.com> References: <20250826075743.19106-1-xupengbo@oppo.com> Precedence: bulk X-Mailing-List: cgroups@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain X-ClientProxiedBy: mailappw30.adc.com (172.16.56.197) To mailappw30.adc.com (172.16.56.197) X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: TY2PEPF0000AB87:EE_|PUZPR02MB6286:EE_ X-MS-Office365-Filtering-Correlation-Id: f49e5922-d95a-4ce8-979c-08dde479055c X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|7416014|36860700013|1800799024|376014|82310400026; X-Microsoft-Antispam-Message-Info: =?us-ascii?Q?a9kzJIYK6mvPaQpqS65Dh7r/+wGJyYLwwTHQadItsYJSVvhghtS15weSbG5k?= =?us-ascii?Q?uL4cCXdOqh2JaiHYmGztTYPhPjziRagXlvSlPcGc5kkRg4+lPXhky5d9kAti?= =?us-ascii?Q?fZ4JzJJpfbUNa31kMk8ADNC0K3iXAZ5bE3P0mEtUMhdWGRMv3oK7ivf8vAha?= =?us-ascii?Q?wXLTDFuAfXy1XbPTJ9ddqgrAHOeHhGqy3wnze+n7nwmdGvCuyvRJZySX4GZ0?= =?us-ascii?Q?/84McxmRkUCH06RuCnLlOj8YghZ+v+GNdN44JOs2m/g+W1gA3Q6cCsVx47/1?= =?us-ascii?Q?YZS55SFzpwLEmucX4EkvR48Kpbea4lWNDuJVFMKXIedAa2Eq04hYdHv5suw9?= =?us-ascii?Q?Okf7FlQ00Dwrgz6xuo3zCsa9bp5qgSz4JJzeHQ5q4LEBBUccojKrjTZwBN6c?= =?us-ascii?Q?pyhzaxubVWls/g/QdQqXEQM9WlIFG7KYzCfDqBs3a/hKW3W6eYFMgL6O6zxu?= =?us-ascii?Q?OyJkYqEICXKK5ZSsObYB6K/BOC9qbquYadySkQ3KFp50dmD+/oy3bmCd3wYq?= =?us-ascii?Q?7/lUZStBMvvk7sny9k+bKxXA621wwvNinSYWl7BjLfyHgtwyiSjpvyUMLdxc?= =?us-ascii?Q?qy8t1ZgESmNPqSHbzrTM9bggd0PnBB2hxTwsMiWtibIWiaN8EwrgeEw1dJ3E?= =?us-ascii?Q?OB4lxyk/p+n8flnIf3Pm8WIv6Hs1/GHHUjOtgBd6TVXIeG0befJyGNRpCZPW?= =?us-ascii?Q?6WHalLMjUMxG8Wf+1VGhE/uIJ/qPD7z6euJfZWWKvwPxmbXuBzrqUt5h44rs?= =?us-ascii?Q?VkGIas1xpITrn9ke3VInOL3ZibkWn/1Edf3NgG1sSgWU/HJ0cyQuzuMjYtJF?= =?us-ascii?Q?GrTDCuKLvExSBnyzOJRN4XSp9IsaWy01lX190etv1rtdBNxR1QPM5Tagdwzz?= =?us-ascii?Q?9hUAOaUvcVN47KoiF/M6dshBBUL2GsrHw+lsDwx9XEH7COX4qttm/ppsAfqP?= =?us-ascii?Q?ZJeUFJ6Zexu/HxPwdR+CN8ZbVPDY84TubpDAYQuuwcTez9Pm9Lyf1I+S2rlz?= =?us-ascii?Q?PmCa1aDJ5E3tImxNIMNmHJ2TQofhMT7ZtgPhO+pGmO71xS2k3O+K83GEln04?= =?us-ascii?Q?JH/zqM8rfQ0g3hREAxWuXadY9hrrSpB0USkQ2kDMgFy4iJBpFGVBlNYtBylH?= =?us-ascii?Q?UwDRSnMsFs+SiYbJ6x7G882pgdCH12r84d8x+PAH++aGTXezGBvN+kshHrwL?= =?us-ascii?Q?C2kDEQTRdS4+znos4lkAkOM0JBM/n9lOIu5n9eGsN0N7NjUYVeH6uTp5KIRO?= =?us-ascii?Q?S1Dr7ZLqCe8FuThfSQJPsxPbQIPPxuq28SmRQA50yCiOwOUOU/9vwc71Bk27?= =?us-ascii?Q?/jmG08/iJL/BYyATA/QUi8AQwkqxFXNfbxess0lYtYczo561/M32viJdfTZK?= =?us-ascii?Q?sHX9aXd1yPOqaQus+O9EqETuwaxro3judJPrLg0AJbhQxZWeQjAsgv/86RL7?= =?us-ascii?Q?JRhCcctQh2YfwwG1KHX002fjlh08uhMbsJJ6wflHfvvNHhFh2ZBnKmm8mIG6?= =?us-ascii?Q?ADDcJZ3J8+uBtYM2jDIpaLaDofibOFnAQDq2?= X-Forefront-Antispam-Report: CIP:58.252.5.68;CTRY:CN;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:mail.oppo.com;PTR:InfoDomainNonexistent;CAT:NONE;SFS:(13230040)(7416014)(36860700013)(1800799024)(376014)(82310400026);DIR:OUT;SFP:1101; X-OriginatorOrg: oppo.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 26 Aug 2025 08:17:38.6745 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: f49e5922-d95a-4ce8-979c-08dde479055c X-MS-Exchange-CrossTenant-Id: f1905eb1-c353-41c5-9516-62b4a54b5ee6 X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=f1905eb1-c353-41c5-9516-62b4a54b5ee6;Ip=[58.252.5.68];Helo=[mail.oppo.com] X-MS-Exchange-CrossTenant-AuthSource: TY2PEPF0000AB87.apcprd03.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: PUZPR02MB6286 >Hi xupengbo, > >On Wed, Aug 06, 2025 at 04:38:10PM +0800, xupengbo wrote: >... ... >> >> It actually becomes: >> if (cfs_rq->tg_load_avg_contrib > 0) >> if cfs_rq->tg_load_avg_contrib == 0 , it will be false. As it is an unsigned >> long, this condition is equivalent to : >> if (cfs_rq->tg_load_avg_contrib) > >I suppose we have reached a conclusion that the right fix is to add a >check of cfs_rq->tg_load_avg_contrib in cfs_rq_is_decayed()? Something >like below: > >diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c >index af33d107d8034..3ebcb683063f0 100644 >--- a/kernel/sched/fair.c >+++ b/kernel/sched/fair.c >@@ -4056,6 +4056,9 @@ static inline bool cfs_rq_is_decayed(struct cfs_rq *cfs_rq) > if (child_cfs_rq_on_list(cfs_rq)) > return false; > >+ if (cfs_rq->tg_load_avg_contrib) >+ return false; >+ > return true; > } > >If you also agree, can you send an updated patch to fix this problem? >Thanks. I already sent an updated patch v3. Link: https://lore.kernel.org/cgroups/20250826075743.19106-1-xupengbo@oppo.com/ Thanks, xupengbo