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McKenney" , David Vernet , K Prateek Nayak , "Gautham R. Shenoy" , Swapnil Sapkal Subject: [RFC PATCH 04/22] [PoC] kernel/sched: Inititalize "kernel_cs_count" for new tasks Date: Thu, 20 Feb 2025 09:32:39 +0000 Message-ID: <20250220093257.9380-5-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: DS3PEPF000099DC:EE_|IA1PR12MB7759:EE_ X-MS-Office365-Filtering-Correlation-Id: 0a3acc76-aa93-4692-50a6-08dd5191d16b X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|82310400026|1800799024|376014|7416014|36860700013; X-Microsoft-Antispam-Message-Info: =?us-ascii?Q?KR2FQmxrpZCgdDCfLscv5/bhwMX+80eCDgVu9ATUGVIEEyUNuWR2fbcAnuk9?= =?us-ascii?Q?qvjXc05e23om97qutRjPy7s+AZVr+CYbJWluFvJ5do9IlgIzKQXZp4LbrdSO?= =?us-ascii?Q?JKdptEVKygSRC1rxKQfSPjZ060bHqkYPjN4U4W0X45aKeGAQKIfvxUznF43D?= =?us-ascii?Q?lGTvxOI6Nq5ydsMW326gC50cRufL6jDlmyCcI92mbTs6YuKLgBhwufyNIz1s?= =?us-ascii?Q?brqFeJQ5foVHkShOiIK6q3Uyesw1VrMik6wp/ujybOiKsvh8LIEMDAQZZ3xR?= =?us-ascii?Q?mcMJSzLWPVEUcW0ISvnqovJ5sChKqUXnL6W0ClJMN4/QZhFxKvd269gGQpMS?= =?us-ascii?Q?YpW3LISib1weKOxqCa5swprE+9Fce72Akq1W7voWy74KCOLU7wBcAqwOwVrz?= =?us-ascii?Q?kdwDGiwLionX01h1wAtpCUiZ08+6CD0l0G8QAKY9QuFjcELD4a5UhDJRlWNG?= =?us-ascii?Q?09mWiBPMf5UaZtjhOj2d510PRYnJ4LmPnlcWV28YE7AtIvbRmy58QAj3oaFS?= =?us-ascii?Q?yz3H2+Qt9Sy4OKCpep1u69qNGHVxZxput5sn5GjPICZVqi9SG6SpedtUf9lS?= =?us-ascii?Q?uBwVKfFpWliGPnp64UXzUTv/DEWRry1lwad8RgbAlBz24Nfgf820mP/yVqVZ?= =?us-ascii?Q?/hDMvYLelVZf0Vby2fN5ENwBO340mESA3qQZ9aorjAwXUhAysq4IOCuyYQBk?= =?us-ascii?Q?Yt7y8EsZPG5++zu0ajHOZHj6C4hQiS46YMJQBULNwLaseb1TA3PHtxXEet9F?= =?us-ascii?Q?1A3LtI3+FjrNr+Q0Yw/k5tL+5KSUaImAkWBMWReiTvLlVcMdpU+SwgAP4d86?= =?us-ascii?Q?SMcCvOLrDDD9oCsDUbF04qsz4gJKrEbYD2LTEbehutQ/6+zgfuQBV3OyEwzE?= =?us-ascii?Q?d8HdyZPArmkv85f2ycx0kuHPEgeank/E85rv+Fi65xGTY3gAXZ6Bi35CJMWv?= =?us-ascii?Q?YAuiSN72yXaPCp1RIXguUcE2xt2/v+Cd/SkE+RJSkPARxG/EM5tHrzDzBTrO?= =?us-ascii?Q?7EQjbZ+7uM6PYQV5hwg51YRql6s9WwTW8a5tfjtxp0KfOnJLiYlp6vyU/OW6?= =?us-ascii?Q?6KJRfyVIv46U280t+qhSrpTQBydwOwJDSsVMocHijKoxv0xH1nFcJ2DkzhNO?= =?us-ascii?Q?R4VqwSZjkS2PI1pAZakQeL0zfFyXdh5mHIh0Wh7sa2jRd5k3pRk7JKrFEeLE?= =?us-ascii?Q?L9xJqWqfO1Ua/ZAkbNN5SsOeZ7/X2l6EjjU/lzpnNw469/eDOxM15ANbZEUk?= =?us-ascii?Q?xbwj2N2Jq0Df15XlW3n0gt/aCNllpp4M6rp85Q6rOvpFBEUxmm1Snfan1aBD?= =?us-ascii?Q?o1W1s7ROUVBbbQNiLqBRAqyT7VvNkSYObYZWzMd0qDH8d/eFIRQfVLTdiQbc?= =?us-ascii?Q?HOsuAm2HSXWffHxg22aAXEtC7YknDnlaOOjvBMctTdNGUyMHGxxi+z11cYrq?= =?us-ascii?Q?3hIOwwpjJYiOoVT344rcDZmuzBokh+ZFggxqsgBs5W7h4uT+ZpFYkk58NOD1?= =?us-ascii?Q?YjhY8h+Qo3fdkjc=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)(82310400026)(1800799024)(376014)(7416014)(36860700013);DIR:OUT;SFP:1101; X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 20 Feb 2025 09:34:48.1119 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 0a3acc76-aa93-4692-50a6-08dd5191d16b 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: DS3PEPF000099DC.namprd04.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: IA1PR12MB7759 Content-Type: text/plain; charset="utf-8" Since only archs that select GENERIC_ENTRY can track a syscall entry and exit for userspace tasks, appropriately set the "kernel_cs_count" depending on the arch. For arch that select GENERIC_ENTRY, the "kernel_cs_count" is initialized the 1 since the task starts running by exiting out of syscall without a matching syscall entry. For any future fine-grained tracking, the initial count must be adjusted appropriately. XXX: A kernel thread will always appear to be running a kernel critical section. Is this desirable? Signed-off-by: K Prateek Nayak --- init/init_task.c | 5 ++++- kernel/sched/core.c | 6 +++++- 2 files changed, 9 insertions(+), 2 deletions(-) diff --git a/init/init_task.c b/init/init_task.c index e557f622bd90..90abbd248c6a 100644 --- a/init/init_task.c +++ b/init/init_task.c @@ -88,7 +88,10 @@ struct task_struct init_task __aligned(L1_CACHE_BYTES) = =3D { .fn =3D do_no_restart_syscall, }, .se =3D { - .group_node =3D LIST_HEAD_INIT(init_task.se.group_node), + .group_node =3D LIST_HEAD_INIT(init_task.se.group_node), +#ifdef CONFIG_CFS_BANDWIDTH + .kernel_cs_count =3D (IS_ENABLED(CONFIG_GENERIC_ENTRY)) ? 1 : 0, +#endif }, .rt =3D { .run_list =3D LIST_HEAD_INIT(init_task.rt.run_list), diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 165c90ba64ea..0851cdad9242 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -4493,7 +4493,11 @@ static void __sched_fork(unsigned long clone_flags, = struct task_struct *p) =20 #ifdef CONFIG_FAIR_GROUP_SCHED p->se.cfs_rq =3D NULL; -#endif +#ifdef CONFIG_CFS_BANDWIDTH + /* Only the arch that select GENERIC_ENTRY can defer throttling */ + p->se.kernel_cs_count =3D (IS_ENABLED(CONFIG_GENERIC_ENTRY)) ? 1 : 0; +#endif /* CONFIG_CFS_BANDWIDTH */ +#endif /* CONFIG_FAIR_GROUP_SCHED */ =20 #ifdef CONFIG_SCHEDSTATS /* Even if schedstat is disabled, there should not be garbage */ --=20 2.43.0