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Shenoy" , Swapnil Sapkal , Shrikanth Hegde , Chen Yu Subject: [RESEND RFC PATCH v2 25/29] sched/topology: Add basic debug information for "nohz_shared_list" Date: Mon, 8 Dec 2025 09:27:11 +0000 Message-ID: <20251208092744.32737-25-kprateek.nayak@amd.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20251208083602.31898-1-kprateek.nayak@amd.com> References: <20251208083602.31898-1-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: satlexmb07.amd.com (10.181.42.216) To satlexmb07.amd.com (10.181.42.216) X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: DS3PEPF0000C381:EE_|SJ5PPFD5E8DE351:EE_ X-MS-Office365-Filtering-Correlation-Id: 8315f365-3c49-4de5-ba49-08de363d131e X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|376014|7416014|82310400026|36860700013|1800799024; X-Microsoft-Antispam-Message-Info: =?us-ascii?Q?VO3OB2d8yGhMx5gr3UqyE3RSDeKewvimDHpCTwN0/rufMAVDMLBpFKp8wmq0?= =?us-ascii?Q?Bm8IpCDf0ReFiZMSUA19p5YT1W2EvOX4bx6LpnCXAk3K4Humq6EXd6ATWSHc?= =?us-ascii?Q?Hy50MAl+YtvU6dcy6WerrDHHHRr1hiS2VEWTABLa3t0VRHwmyFnZ1p2GMyBt?= =?us-ascii?Q?Hqvq4gOf0KXdQmAgWzdslJDhNE/MRrODNlC67AZ5QELgGcLHivO8aJh1VucC?= =?us-ascii?Q?bRgHKH0HHdDfOC6M998a5i1N9BdzVb0y0lEPcOgS4PgQvVRNG4ZdmaQ/9NAq?= =?us-ascii?Q?h5GgXE7L9TB6GdrpWzSnu1kNQNWsjzLuCBIcElbQHwJJTFhxQkRlVHVFZAA8?= =?us-ascii?Q?2/aEPQ2Wwdbp6ZuWfKTt/Av5pzVQ6sZDDe2c4FAzo694Kfh4MX4rK5PiL+8F?= =?us-ascii?Q?JSVEppcK8I0Fdxrk7kB1v2fKFF+m3fp99YQceUKd8OePrCPlT6Vb+8z6MyEP?= =?us-ascii?Q?HQ1W/1zJrEhWkmDHWoDEc/rWr0elzhYYqPERtbcGyS+yT//EH5NSdrXYOJvL?= =?us-ascii?Q?IiMTMDnd98V8zIJRMmcsIsObhodzAJltMmzwNB4mecslDB9SFZ1y0SjLMr7j?= =?us-ascii?Q?iF/LjR8E3QjDD87xZ59+HxeedJLTYpKarwr6T/BXSUZe2gzYpW+Y55xT08qr?= =?us-ascii?Q?mJvQflqkyxXVNigd5/NLk/3qJYNS2e2kEz2RNkAr2IFNnqxcq/b2h229hmOc?= =?us-ascii?Q?r/X+bX2qwuXzRNcX89ToN4N7U0831THSEESVVs58GuviKtcG6hZd0hWYLjsc?= =?us-ascii?Q?pBr6EqeMnbJzm9V23cf97FpD52mqyQd5Qj0RdYsuNfbAthIwiuCEvIPK7BQV?= =?us-ascii?Q?8cq1TtYJIky8ybNW/vVm1CO6PuFpHMzleKM6Iui2dDo7korVtU8uO4w56VSo?= =?us-ascii?Q?RIG2nRHrzVENIZK6JlG3Cb9i0HqWKf9gOFx+FyOvOMHtVMV4w3ZyzKFQmqUc?= =?us-ascii?Q?hmQXE1wJD828WQul7KWcdLaPYJSgZ0BuEX+q+MEzgABJZPEUptF+3SSbOi1e?= =?us-ascii?Q?gJtEtKBuKVlSunXzlYOatGFEze0LS4lwOvGuT/4jcqqDvVD4AVyfk52zxMQR?= =?us-ascii?Q?lYLlv3z94kaDZrR078hxNorHkEydYnFJGRIt6MeoFO7MieNk7xZNMobAOI0j?= =?us-ascii?Q?h+2hPhLIuffb3bbLvOFMI0sSkdwqRPSLrwAPMiVHJTVoc2SqAd+hO26cX6fw?= =?us-ascii?Q?P4iO7wJMNkwC6zQ9w4pu2nlFYLIlkscAwMi/7hDNpRnQZqFxmAQFvqkL6RLZ?= =?us-ascii?Q?Gpwe+sKXxPVsMekFb8kRdYdp+fTyLL0yx554jf1Kzh94yzeevzpbsiqM49Rx?= =?us-ascii?Q?NGX6CruOfpuD0BcY5C7CyneK9Ci0NPYoNsXGcxDMIkIX4GtMZpW2GAPLPTHv?= =?us-ascii?Q?eUd5C+a1KDJmxxuP0t7lBe9MC/OeFWYdWA4k19OETkEbykm/kOPLHDeamqPJ?= =?us-ascii?Q?HGoSSSALonMK56SDZsf42n/wm4JfIHZXQHxnzOjiWLNyTPKHryWJ6wpWUZE1?= =?us-ascii?Q?Ehgwd2HRnLejt9OonLnN0C/a0377DNq0LpV3wF8CvONQ7RgqIRvffn691SoW?= =?us-ascii?Q?YDP/27puAW0wG6dwQe0=3D?= X-Forefront-Antispam-Report: CIP:165.204.84.17;CTRY:US;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:satlexmb07.amd.com;PTR:InfoDomainNonexistent;CAT:NONE;SFS:(13230040)(376014)(7416014)(82310400026)(36860700013)(1800799024);DIR:OUT;SFP:1101; X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 08 Dec 2025 09:35:07.4262 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 8315f365-3c49-4de5-ba49-08de363d131e 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=[satlexmb07.amd.com] X-MS-Exchange-CrossTenant-AuthSource: DS3PEPF0000C381.namprd04.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: SJ5PPFD5E8DE351 Content-Type: text/plain; charset="utf-8" Introduce debug_nohz_shared_list_update() to count the number of entries in "nohz_shared_list" after each list modification. XXX: There isn't a great way to jump from a sched_domain_shared object to the sched_domain struct that references it which prevents printing more information about the sched domain that was linked with the shared object. Signed-off-by: K Prateek Nayak --- kernel/sched/topology.c | 19 ++++++++++++++++++- 1 file changed, 18 insertions(+), 1 deletion(-) diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c index ec549fb7d7fc..738e6084d5be 100644 --- a/kernel/sched/topology.c +++ b/kernel/sched/topology.c @@ -471,6 +471,20 @@ DEFINE_PER_CPU(struct sched_domain __rcu *, sd_nohz); static DEFINE_RAW_SPINLOCK(nohz_shared_list_lock); LIST_HEAD(nohz_shared_list); =20 +static void debug_nohz_shared_list_update(void) +{ + struct sched_domain_shared *sds; + int count =3D 0; + + if (!sched_debug()) + return; + + list_for_each_entry(sds, &nohz_shared_list, nohz_list_node) + count++; + + pr_info("%s: %d nohz_shared_list entries found.\n", __func__, count); +} + static int __sds_nohz_idle_alloc_init(struct sched_domain_shared *sds, int= node) { sds->nohz_list_node =3D (struct list_head)LIST_HEAD_INIT(sds->nohz_list_n= ode); @@ -588,6 +602,7 @@ static void update_nohz_domain(int cpu) =20 guard(raw_spinlock)(&nohz_shared_list_lock); list_add(&sds->nohz_list_node, &nohz_shared_list); + debug_nohz_shared_list_update(); } =20 WARN_ON_ONCE(sd && !sds); @@ -612,8 +627,10 @@ static int sds_delayed_free(struct sched_domain_shared= *sds) if (list_empty(&sds->nohz_list_node)) return 0; =20 - scoped_guard(raw_spinlock_irqsave, &nohz_shared_list_lock) + scoped_guard(raw_spinlock_irqsave, &nohz_shared_list_lock) { list_del_rcu(&sds->nohz_list_node); + debug_nohz_shared_list_update(); + } =20 __nohz_exit_idle_tracking(sds); call_rcu(&sds->rcu, destroy_sched_domain_shared_rcu); --=20 2.43.0