From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from LO2P265CU024.outbound.protection.outlook.com (mail-uksouthazon11021137.outbound.protection.outlook.com [52.101.95.137]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id B6D0E344D8C for ; Mon, 10 Aug 2026 01:58:37 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=fail smtp.client-ip=52.101.95.137 ARC-Seal:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786327119; cv=fail; b=WplK7hPMz8iQdduoB1Q4bEhmyj837GOcVSN8FWoivTfHbueS2zsm7IW7qh3nhEF6gOgOdbsbfu1cUpL/kolBTiqaclp28aaryAle72aKRVp5MAiUWoWXKJjGF8DgtNQr/moddSv23QIOG0M+T7Jqj6bGewRzAloUB/DlLASQqDw= ARC-Message-Signature:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786327119; c=relaxed/simple; bh=cgxtAvd5It8+cr8z6kHqSldyp3B0lmNP9JxpAiuLXFo=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: Content-Type:MIME-Version; b=Qs4e0TP9ZM0cBkiHALv3YKYIyBFBIDl/epDxZ7Ag7F6bFRLkpUpnOBbBqrNe0TVAgPv9yvzEMQcHBFPNElxwgLR/N0jZkbW7BP7A1JowmiYm3ef2zieqclp5lct1Ga6GmQL1XsWZnWsnodzsInSZkYcO2B1FLziBz4ladOUWED4= ARC-Authentication-Results:i=2; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=atomlin.com; spf=pass smtp.mailfrom=atomlin.com; arc=fail smtp.client-ip=52.101.95.137 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=atomlin.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=atomlin.com ARC-Seal: i=1; a=rsa-sha256; s=arcselector10001; d=microsoft.com; cv=none; b=ap9ouKQvuSz6xx7R6FNVYvbUnvc4C2GrC8t0Q6zIbsbXpHGeNGjusoCUzdNQsbPolkjxhNRnPoo+29vjb04uxvO64kG+G+VArjnHBHbum/KtlSwQWqDHCSx0pzr67ry44EWzdjfz86xYI4voDRXnqmuDLslfD/9NKDchzBqp3CLqgTaovmwlYekktfL9Z1N7eAWxbenJ44py2KxA7bHO1oQ922WZyIDtIYpimeqlpmZGOOEkWleI1BCtMtJja+z0JoQbtACEmbYEQagRS7RJVBY3hB343c/Bcv3temQAM9/Pc1MiEwsptJ6MJ9V+dMcBURjlu2b/+ihCJe2bXtq6Mg== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=microsoft.com; s=arcselector10001; h=From:Date:Subject:Message-ID:MIME-Version; bh=+PyDN/OsfN5K5QRuQ0sEMIYoRc74wGxBQXwRWY7p/y0=; b=cpyMFCckQgTIivIDHR3PLT54hPUFcWDuMZiA8TVlrvZHAJhHLAj7joWgGXxCAwYtKph6DK4eST14q7RE9YBfUO8QFnTTwCNLQomVIBHfareNQr1YJFiEqQ2Fa1ZQwmlXHa6GLUIkL+qrVATTNwN6QHox07sSQVEmAt9IHRtsPBDPiiJNiQ7xJEzWRPKw4UfdL9kJ7qS5/MH4w3bA/din3U8qVi9P9ekpJo+oD/tv3kzqDe0CZBmn9K/IsGfA7JBgWYCuAI4Dd/qd6Xc/hNGQQh2gj/ZGFBdsAWzGVEFMJHutbQBQwjLyAglcS0TkJtBT2FFDBcD+b7+mnecZlzLk1g== ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass smtp.mailfrom=atomlin.com; dmarc=pass action=none header.from=atomlin.com; dkim=pass header.d=atomlin.com; arc=none Authentication-Results: dkim=none (message not signed) header.d=none;dmarc=none action=none header.from=atomlin.com; Received: from CWLP123MB6607.GBRP123.PROD.OUTLOOK.COM (2603:10a6:400:183::5) by CWLP123MB3891.GBRP123.PROD.OUTLOOK.COM (2603:10a6:400:a2::6) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.21.292.25; Mon, 10 Aug 2026 01:58:35 +0000 Received: from CWLP123MB6607.GBRP123.PROD.OUTLOOK.COM ([fe80::cec4:77ab:262e:d230]) by CWLP123MB6607.GBRP123.PROD.OUTLOOK.COM ([fe80::cec4:77ab:262e:d230%4]) with mapi id 15.21.0292.024; Mon, 10 Aug 2026 01:58:35 +0000 From: Aaron Tomlin To: mingo@redhat.com, peterz@infradead.org, juri.lelli@redhat.com, vincent.guittot@linaro.org Cc: dietmar.eggemann@arm.com, rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de, vschneid@redhat.com, kprateek.nayak@amd.com, zhanxusheng1024@gmail.com, neelx@suse.com, chjohnst@mail.com, mproche@mail.com, sean@ashe.io, steve@abita.co, linux-kernel@vger.kernel.org Subject: [PATCH v4 5/5] sched/debug: Introduce per-CPU debugfs files Date: Sun, 9 Aug 2026 21:58:12 -0400 Message-ID: <20260810015812.428999-6-atomlin@atomlin.com> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260810015812.428999-1-atomlin@atomlin.com> References: <20260810015812.428999-1-atomlin@atomlin.com> Content-Transfer-Encoding: 8bit Content-Type: text/plain X-ClientProxiedBy: BN9PR03CA0586.namprd03.prod.outlook.com (2603:10b6:408:10d::21) To CWLP123MB6607.GBRP123.PROD.OUTLOOK.COM (2603:10a6:400:183::5) 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: CWLP123MB6607:EE_|CWLP123MB3891:EE_ X-MS-Office365-Filtering-Correlation-Id: f3239ccb-61f0-4a8f-f2e0-08def682e359 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|23010399003|366016|1800799024|376014|7416014|5023799004|56012099006|10067099003|3023799007|22082099003|18002099003; X-Microsoft-Antispam-Message-Info: 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 X-Forefront-Antispam-Report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:CWLP123MB6607.GBRP123.PROD.OUTLOOK.COM;PTR:;CAT:NONE;SFS:(13230040)(23010399003)(366016)(1800799024)(376014)(7416014)(5023799004)(56012099006)(10067099003)(3023799007)(22082099003)(18002099003);DIR:OUT;SFP:1102; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?I2emQ0W9vXtMS8SWgXtjIj53ffYSdYW2pmGN6g475c4yTilFcDv6mJWdk5jG?= =?us-ascii?Q?Yyipouz6WLzXRyhPEI3NnypelamhvkEfwwZT3eBGEXt691aYdKaTEul4ncSR?= =?us-ascii?Q?AgT/iiO5E2TSF/2Cq3ymLYse8VEhEyJJe/hVDxnxXOm6T332vEbq4kT5KvnR?= =?us-ascii?Q?8ZcgmYqRcWsRCuIzGDVWc5Eh45hiXWE1IN29Hu8YjhZAh6Y636TcHEs3IITm?= =?us-ascii?Q?QwuT6I8rOknQMVeEoEOnLc7TreayX+AgMh1Res3NKM/99KQ08MPWO6adIwCA?= =?us-ascii?Q?5+LK8KjDVaZdD6siE3HXob5RlKcHkFwkomLN1rgPhoapE20PHUNB6jGj/+sZ?= =?us-ascii?Q?zNCr9sjfXsvDVPnLqYfy+2Kekmfn6iuCptEjTa+R7JAdisi3ZgcbGCQLpaL2?= =?us-ascii?Q?PM5CFOxd9CI+j6NHLEsihT72goPAQLETMcjAgIlE26rv5V/koHxoMnWQSqyF?= =?us-ascii?Q?Vt6lwF1dsOsExm+0B7AT1HlITDtitAvB4GtnaG+Tonmynom2/P2HTnyFb1se?= =?us-ascii?Q?cfEKhybUEdfL9v/NolF5h3HwLyP7A3DbiHn9Sl8x0mEA8kWtDdcW9YMNtMr+?= =?us-ascii?Q?SZaV9BL7J6SIw+GcEJzy4YH3J1NfjfROjWJ2BalzkTg6ii1CFJ4qJowFFFFq?= =?us-ascii?Q?cl1PMVEbOpMfKaf7WOO4vXzB559+0sXl5qvB0MTScVNMyBjfArQEPL1oqAzT?= =?us-ascii?Q?zfwb3MVf/YSQO8r/zVUSrhDVAL2PJ0EoIYo6G3OaNCthZoVUizXDiZetPDWG?= =?us-ascii?Q?woLbxX3NmV5sEHBYmvzWdiP8TAhueguZjg0FVL3EgdIVVyOWI9c6ylH5sv7M?= =?us-ascii?Q?e7kPhpGp6qD3+9M9K2F4CE/CO+5qfBpNLh2Kvm7f+BPx/BaxfEyws0p8ThNS?= =?us-ascii?Q?jEmmq7/5cpyznGM2G2xC7syLfHW9Ui5q1h34eXShLAlcixY7NxVnElzFgyqn?= =?us-ascii?Q?4oTKO9+QTSVZmAD/W+QvWlo3b3jitdRdhYesegBf4lOpzv9Z2Dw1DnF7V1U7?= =?us-ascii?Q?lIodqnnsDGiq0U56wab92ynMI4uXfgE/v5BLAD0YImtEiPu/qn/amxZKaMaG?= =?us-ascii?Q?q1OvFBrk2QOeq44ju812GiP9y6TYcmVuMAQmoOnWDlRiBgwbPSKfD8KYJp7r?= =?us-ascii?Q?Hk08SNxI6DL2gVKbWx/imcLW+NKxqgqzCWtpoX79XhHhS//SDoIzkCVWKd5j?= =?us-ascii?Q?ZErmlU4GHpV+3dnHEGAQ2njPjFj+MStIzL01hZccdUBRztAhY7w4EfJs0uFx?= =?us-ascii?Q?AV4F3MWAdbwMSJ9kztXjZH98m0oSWbOODIG35fTgYuzu5MtbY90XmuVTIOXM?= =?us-ascii?Q?JLPMiPVMqEyCgylfWlR7WP6ynt//i+ltDs7kcTSiRCNgWpmqEv2P3nQXovb0?= =?us-ascii?Q?PExRdGQUaXUho7WERG/+1mFCaBEOSH7tP449baRFh7Kyvo5A6eSML+eu6KyL?= =?us-ascii?Q?+M6tiREiYHCC6bKM2hqZfGMRaq56lJhVDUyI1F34ceOCltIgVe431w2bAHeR?= =?us-ascii?Q?gCZvwa5ToMEJG2U206OCa+i3IZh5wu3gVz16S4dGGIVfA44Dl73jJQMuotpw?= =?us-ascii?Q?PM+8mxuHEylg/9BdNuw9okeHCZG9varrmNTeRgr7k3k5vyAjLXSa/f6YTcpV?= =?us-ascii?Q?ekxGNu5Hx5A0rtTtj0J+d6+4FrmHhrILxf9I0kOFQQr3Nqcd4//GXjDgPwFg?= =?us-ascii?Q?JnWNykEA01mfDhBuUKyT6pwVzpn06SFKGDdhIf2SpP57fvenJXgjP2EhB7ol?= =?us-ascii?Q?HoVzyTBYAg=3D=3D?= X-OriginatorOrg: atomlin.com X-MS-Exchange-CrossTenant-Network-Message-Id: f3239ccb-61f0-4a8f-f2e0-08def682e359 X-MS-Exchange-CrossTenant-AuthSource: CWLP123MB6607.GBRP123.PROD.OUTLOOK.COM X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 10 Aug 2026 01:58:35.5412 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: e6a32402-7d7b-4830-9a2b-76945bbbcb57 X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: sAWn9V5jHslwiF27LIAOob0YrxenWziIG3i4RwDh5EFqBi4EgpRcWDCP4pOpz4BX8F3P2hzVaeIxLRUlgcPePg== X-MS-Exchange-Transport-CrossTenantHeadersStamped: CWLP123MB3891 Currently, accessing scheduler debugging details for a specific CPU requires reading /sys/kernel/debug/sched/debug, which outputs information for all online CPUs. When investigating a latency anomaly or scheduling issue isolated to a specific CPU, accessing /sys/kernel/debug/sched/cpu/cpu/debug provides an immediate, targeted view of that runqueue. Add support for per-CPU debug files under: /sys/kernel/debug/sched/cpu/cpu/debug. Reading /sys/kernel/debug/sched/cpu/cpu/debug calls print_cpu() specifically for CPU , exposing CPU-specific runqueue details on demand. If the target CPU is currently offline, reading its file returns -ENODEV. Signed-off-by: Aaron Tomlin --- kernel/sched/debug.c | 43 +++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 43 insertions(+) diff --git a/kernel/sched/debug.c b/kernel/sched/debug.c index f5494e02f600..22e917db86fa 100644 --- a/kernel/sched/debug.c +++ b/kernel/sched/debug.c @@ -356,6 +356,7 @@ static const struct file_operations sched_verbose_fops = { }; static const struct seq_operations sched_debug_sops; +static void print_cpu(struct seq_file *m, int cpu); static int sched_debug_open(struct inode *inode, struct file *filp) { @@ -633,6 +634,47 @@ static void debugfs_fair_server_init(void) } } +static int sched_debug_cpu_show(struct seq_file *m, void *v) +{ + unsigned long cpu = (unsigned long) m->private; + + if (!cpu_online(cpu)) + return -ENODEV; + + print_cpu(m, cpu); + return 0; +} + +static int sched_debug_cpu_open(struct inode *inode, struct file *filp) +{ + return single_open(filp, sched_debug_cpu_show, inode->i_private); +} + +static const struct file_operations sched_debug_cpu_fops = { + .open = sched_debug_cpu_open, + .read = seq_read, + .llseek = seq_lseek, + .release = single_release, +}; + +static __init void debugfs_cpu_init(void) +{ + struct dentry *d_cpu_dir; + unsigned long cpu; + char buf[16]; + + d_cpu_dir = debugfs_create_dir("cpu", debugfs_sched); + + for_each_possible_cpu(cpu) { + struct dentry *d_cpu; + + snprintf(buf, sizeof(buf), "cpu%lu", cpu); + d_cpu = debugfs_create_dir(buf, d_cpu_dir); + + debugfs_create_file("debug", 0444, d_cpu, (void *) cpu, &sched_debug_cpu_fops); + } +} + static __init int sched_init_debug(void) { struct dentry __maybe_unused *numa, *llc; @@ -690,6 +732,7 @@ static __init int sched_init_debug(void) #ifdef CONFIG_SCHED_CLASS_EXT debugfs_ext_server_init(); #endif + debugfs_cpu_init(); return 0; } -- 2.55.0