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Shenoy" , Swapnil Sapkal Subject: [RFC PATCH 18/22] sched/fair: Prepare pick_next_task_fair() to unthrottle a throttled hierarchy Date: Thu, 20 Feb 2025 09:32:53 +0000 Message-ID: <20250220093257.9380-19-kprateek.nayak@amd.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20250220093257.9380-1-kprateek.nayak@amd.com> References: <20250220093257.9380-1-kprateek.nayak@amd.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-ClientProxiedBy: SATLEXMB04.amd.com (10.181.40.145) To SATLEXMB04.amd.com (10.181.40.145) X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: BN1PEPF00006000:EE_|DM4PR12MB6374:EE_ X-MS-Office365-Filtering-Correlation-Id: 67f52316-b2f8-46ae-9544-08dd5192805e X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|36860700013|376014|7416014|1800799024|82310400026; X-Microsoft-Antispam-Message-Info: =?us-ascii?Q?CxQW7bwgpfXg25aL97GPifQFRmHzaduCZFDv4TiMr+EIHjSrU7YrDm3zaRPO?= =?us-ascii?Q?n2A94ZBhQKmF2kCAQa2l9xM9lGGYai6IIuNSesT95EhM/bzLDKLuzAYDKLIk?= =?us-ascii?Q?SMI2zGTnQ3kByKxq204r/L2wFwyy6qwMGp+aeeLxpHIAywD7mK/OzatJSpkY?= =?us-ascii?Q?fefZO83DpspZ5C65/RuAT/hEUU0voEbJwDXiYlcb+GPZGz3lNXJiJALupApk?= =?us-ascii?Q?SHVvFn9M0eUyqM9JHfi8umkchztkwczGqpO/xYGk/E/NooyguWE/zEY427E2?= =?us-ascii?Q?AmkeMqyo0zVo8B185uUElp+M7TChom3oARD4vu2859abRCw79SXHwwIW4lPk?= =?us-ascii?Q?z87VKm11Wckg8N5kCDKd9v+1IGAgTkRdJ9ROrwKkacPcyjbt0VCcgQaS+1K7?= =?us-ascii?Q?fXs4Vmh4iSXtqCPLNs2tugkPd3us35m8puGoi5CuLoeyasKoninTdt6O8W3H?= =?us-ascii?Q?g2Q7gtagTGg6iDt2UH5/WTOgU1hVLpkWaFxwHG4/1RT2EjoNLGxK7LDUzBUT?= =?us-ascii?Q?FwuIW/0b2X9KOOHypOsNYTXmqp2tF6U/+8GRR3M4NtR+B/tGNq0epLRmB8Ka?= =?us-ascii?Q?PZE1HEXcSGYduoaEUgu5ed5GZ6RY0d6pQQ4YrEWFyQT3olpjQ3yCGCtFI70k?= =?us-ascii?Q?bxPDvwvrNbcNaQnq5UQLqiEUQPPH4eqR1OhIdJtqRh0mSp6+lPLCRiuniDb7?= =?us-ascii?Q?QbsgsYyiRGwmdPGgaEp1R3N8iO1GHEw4LS1C7RGH6hBCJCP8wh4mUIxay+sd?= =?us-ascii?Q?IOZ5b4sBkib183AgQB1NdlyVQd8NJOnz7dzJcaXWmHF+G81qRVk877pyEekM?= =?us-ascii?Q?LbMMTbTJH0gFjDTs11JCCfc/TjYOXKq4DfNJ9N+cICxJR4T99ohw2wu47N2X?= =?us-ascii?Q?NIGOLddyxz2aWZr5LC7QC01b011mhsJnbom5hcNSogoaigTRCooHNtEr9p37?= =?us-ascii?Q?70s9L08w0s+7T8AzQXWXj/gtMg1dxWzzC9cyeReL1J/oVe7JTxnapNHgqxpa?= =?us-ascii?Q?dLDFnulPONIonz69jRksmGbtnE7fVfArkPJsi5X53puJLx4vUyMxboAH4xEL?= =?us-ascii?Q?HDeaFwV/3jrjx9SUCImNRXDh3kd23ShYuPLm5aFqU96tYq/6ZO/JPlyrB70J?= =?us-ascii?Q?ciKGXAD5f0pEcXNbsmTpQGyyqsCdUceiYDznRvQZBs+r2pBBYgZi/gGka3NF?= =?us-ascii?Q?Uz+DwHyGbO0AW+7fjxBo/NAmJthK9cmA7UCYF50QKnv+YqIlVcOYJH5xclY0?= =?us-ascii?Q?jXzgs+LYtOJzHZp/JH/zbV6qBpzcj0fNaaY6Q43msh8ChwRjilw1rvx4tR44?= =?us-ascii?Q?wkCdsfYExVwFCO39TtpALZalHJYsNke02C5+3aFNb7QdE4It1ZYLDqX3+zjH?= =?us-ascii?Q?1l/ASBsXNFV3Jt5BRmKPN6LJhPXKh7mvLEviMZKmSV0TeEwYSqRzyfTCd1jj?= =?us-ascii?Q?3OdC9RsTRNOOsSCnluS5t27YatH17EjCve2KCiPWND4haB5iuEfBVaDBAZu/?= =?us-ascii?Q?RjT9NUcMf3sT6Lc=3D?= X-Forefront-Antispam-Report: CIP:165.204.84.17;CTRY:US;LANG:en;SCL:1;SRV:;IPV:CAL;SFV:NSPM;H:SATLEXMB04.amd.com;PTR:InfoDomainNonexistent;CAT:NONE;SFS:(13230040)(36860700013)(376014)(7416014)(1800799024)(82310400026);DIR:OUT;SFP:1101; X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 20 Feb 2025 09:39:41.6767 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 67f52316-b2f8-46ae-9544-08dd5192805e 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: BN1PEPF00006000.namprd05.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: DM4PR12MB6374 Content-Type: text/plain; charset="utf-8" Kernel mode preempted tasks being put back on a throttled hierarchy needs to be reachable during pick. Demote the throttle status to partial if pick_next_task_fair() finds that the previous task was preempted in kernel mode but is on a fully throttled hierarchy. Signed-off-by: K Prateek Nayak --- kernel/sched/fair.c | 32 ++++++++++++++++++++++++++++++++ 1 file changed, 32 insertions(+) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 423c5a95989e..1497b0aed1c2 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -9407,6 +9407,38 @@ pick_next_task_fair(struct rq *rq, struct task_struc= t *prev, struct rq_flags *rf struct task_struct *p; int new_tasks; =20 +#ifdef CONFIG_CFS_BANDWIDTH + se =3D &prev->se; + + /* + * A task on throttled hierarchy was forced into running state. + * Recheck throttle status when the task hits schedule since the + * "kernel_cs_count" is stable now. If task is preempted in + * kernel mode, partially unthrottle the hierarchy now for it to + * be reachable for pick_task_fair() that follows later. + */ + if (prev->sched_class =3D=3D &fair_sched_class && + task_on_rq_queued(prev) && + se_in_kernel(se) && + throttled_hierarchy(cfs_rq_of(se))) { + struct cfs_rq *cfs_rq =3D cfs_rq_of(se); + + for_each_sched_entity(se) { + cfs_rq =3D cfs_rq_of(se); + + /* There is at least one fully throttled cfs_rq */ + if (cfs_rq_h_throttled(cfs_rq)) + break; + } + + /* + * Only unthrottle; Do not adjust "kernel_cs_count" yet + * since account_kcs_enqueue() below will adjust it. + */ + unthrottle_throttled(cfs_rq, false); + } +#endif + again: p =3D pick_task_fair(rq); if (!p) --=20 2.43.0