From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from MW6PR02CU001.outbound.protection.outlook.com (mail-westus2azon11012016.outbound.protection.outlook.com [52.101.48.16]) (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 164D62D8DB0 for ; Fri, 23 Jan 2026 16:48:45 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=fail smtp.client-ip=52.101.48.16 ARC-Seal:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769186929; cv=fail; b=QL3E5ACHwYJlp55wDOn+NhlZsqP3HG7DZLpYEdrkwEIbNpMVy6Tlt68tYopQH0UoxMy9V3u2tAihkcfRqz004R8yrixTFj44hSJk809XxbfN0NOBIAGyUKVAZtaXzftyKE8n8aY0V7WUyNTxWiA6sBy22chVLyGiZcOD+Zi6OPM= ARC-Message-Signature:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769186929; c=relaxed/simple; bh=p1/SIYX23ufMULD3ZaznAq7OUFACSgLlPutqSAuc+os=; h=Message-ID:Date:MIME-Version:Subject:To:CC:References:From: In-Reply-To:Content-Type; b=VENfyEwadFk/D+KZH+2J/g5qTW/YncJz6HW4AUM51j9caF/n+mEJB0UJbGLlg/JECj4MgMsWxTTQXtKnmplf48xws3MFE4rReQJ5mmmTur4RKjvFwZ42A+z1PIgLZgddLtvMINB5zv3ziNjj8hjRmU1nuLMSVpja5xT4gIMghCE= ARC-Authentication-Results:i=2; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=amd.com; spf=fail smtp.mailfrom=amd.com; dkim=pass (1024-bit key) header.d=amd.com header.i=@amd.com header.b=IJ/AhZmA; arc=fail smtp.client-ip=52.101.48.16 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=amd.com Authentication-Results: smtp.subspace.kernel.org; spf=fail smtp.mailfrom=amd.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=amd.com header.i=@amd.com header.b="IJ/AhZmA" ARC-Seal: i=1; a=rsa-sha256; s=arcselector10001; d=microsoft.com; cv=none; b=AFo5ErXUy7cvJe4rqx8uFKZGb000+FvatskN22C5UTEgwdpFpQm8jWLKwZhCLziz8ZvdJ3FWPoCgDec7rUbVTh9yZlwCNnAOgsOKld4JEgnTHLic2crkudFiP15HW91GfoyyFpR/ULKt69t5jrbH+XgPEhFcn37y/HT8irqRop1bw0uQR9A+4JHScn8evpN6liBgz/55b+thx5F4ezFkq9Dz3A6SaP65lUy/UC5PigLuezVd9OCOsO5gEz1o9fArjdd4UJ9TG9PG8iU3XNsHABDpRuwFAgtwhVuLDgU2iKG5jDiW1Ys0pLkqkg6N43OvjjPgpHaOpunAbLNC0jaBWw== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=microsoft.com; s=arcselector10001; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-AntiSpam-MessageData-ChunkCount:X-MS-Exchange-AntiSpam-MessageData-0:X-MS-Exchange-AntiSpam-MessageData-1; bh=6HwZlO0VNs7TVVEFt/frq77rd2oedYF5NRb1RpHUfzY=; b=T/lI8c2/oS1OPrMTCS0OLS/6yD3p4kAekn3lJ/e5gfooUSuwMNcn4QMUE9rjkQZnI9eObRVyh36zuPyF837PjKuFsQYTDhJRo4qNXwFOopW9mx5Iuh9aCDkF5KhI0xIWY3X+eYpYqfRjjgKURJhMvdIzec3X9396NmstnKTmcpAhDZSHBubFhd8vBQSqjsIjeJk2KtA8VARxXbKXISgyVNevJVv2y3Yryht0+l/ddjUzMduPUoboWMppI/4Xj7jqs5L40/09tgLgibO7Stu9GgOaY7qks503IA9dQH5zMxjbxjDkDM3ooQiB8NendJDC5XfVlLr/FgHMAQMw3xpIlA== ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass (sender ip is 165.204.84.17) smtp.rcpttodomain=linaro.org smtp.mailfrom=amd.com; dmarc=pass (p=quarantine sp=quarantine pct=100) action=none header.from=amd.com; dkim=none (message not signed); arc=none (0) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amd.com; s=selector1; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=6HwZlO0VNs7TVVEFt/frq77rd2oedYF5NRb1RpHUfzY=; b=IJ/AhZmAhF59+vFILW9Oz6wJ38s45FDe7YYc99F2hWq5HA5Educcb+6G+3tZrODJguUvGGGbeZMzq/MZiaK0Vumd/3HcUpCOlzJUY8B1M3cEXrox5fa6kC2HrdDZLKAOo3aZiz39T63dYoAjaI/01plZKlgImlFGobN+4bbS0v8= Received: from PH8PR07CA0020.namprd07.prod.outlook.com (2603:10b6:510:2cd::12) by DS0PR12MB8413.namprd12.prod.outlook.com (2603:10b6:8:f9::7) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.9542.11; Fri, 23 Jan 2026 16:48:39 +0000 Received: from SJ1PEPF000023D7.namprd21.prod.outlook.com (2603:10b6:510:2cd:cafe::62) by PH8PR07CA0020.outlook.office365.com (2603:10b6:510:2cd::12) with Microsoft SMTP Server (version=TLS1_3, cipher=TLS_AES_256_GCM_SHA384) id 15.20.9542.11 via Frontend Transport; Fri, 23 Jan 2026 16:48:34 +0000 X-MS-Exchange-Authentication-Results: spf=pass (sender IP is 165.204.84.17) smtp.mailfrom=amd.com; dkim=none (message not signed) header.d=none;dmarc=pass action=none header.from=amd.com; Received-SPF: Pass (protection.outlook.com: domain of amd.com designates 165.204.84.17 as permitted sender) receiver=protection.outlook.com; client-ip=165.204.84.17; helo=satlexmb08.amd.com; pr=C Received: from satlexmb08.amd.com (165.204.84.17) by SJ1PEPF000023D7.mail.protection.outlook.com (10.167.244.72) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.9587.0 via Frontend Transport; Fri, 23 Jan 2026 16:48:37 +0000 Received: from SATLEXMB03.amd.com (10.181.40.144) by satlexmb08.amd.com (10.181.42.217) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.2.2562.17; Fri, 23 Jan 2026 10:48:36 -0600 Received: from satlexmb07.amd.com (10.181.42.216) by SATLEXMB03.amd.com (10.181.40.144) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.39; Fri, 23 Jan 2026 10:48:36 -0600 Received: from [172.31.184.125] (10.180.168.240) by satlexmb07.amd.com (10.181.42.216) with Microsoft SMTP Server id 15.2.2562.17 via Frontend Transport; Fri, 23 Jan 2026 08:48:31 -0800 Message-ID: <802dccf4-4357-40b1-89a9-94962b6f7dbf@amd.com> Date: Fri, 23 Jan 2026 22:18:30 +0530 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3] sched/clock: Avoid false sharing for sched_clock_irqtime To: Vincent Guittot CC: Wangyang Guo , Peter Zijlstra , Ingo Molnar , Juri Lelli , Dietmar Eggemann , "Steven Rostedt" , Ben Segall , Mel Gorman , Valentin Schneider , , Shrikanth Hegde , Benjamin Lei , Tim Chen , Tianyou Li References: <20260116023945.1849329-1-wangyang.guo@intel.com> <95f2091c-273e-4e36-b543-735748efd5fc@amd.com> <648b2b54-7432-4578-b785-030d98f6e31c@amd.com> <653ac450-2f00-4eb0-bb97-e40576435462@amd.com> <0b625352-f0e0-49c6-83a2-a69250c6caeb@amd.com> Content-Language: en-US From: K Prateek Nayak In-Reply-To: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Received-SPF: None (SATLEXMB03.amd.com: kprateek.nayak@amd.com does not designate permitted sender hosts) X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: SJ1PEPF000023D7:EE_|DS0PR12MB8413:EE_ X-MS-Office365-Filtering-Correlation-Id: db7c948b-e339-4995-365c-08de5a9f4142 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|376014|7416014|1800799024|82310400026|36860700013; X-Microsoft-Antispam-Message-Info: =?utf-8?B?Y3ovTXdhdWE4NDdZUGFoMU03LysvbHR3YkdtVGsvYjV1aFFPcW5GN0JTb2xo?= =?utf-8?B?bVhKUDBWY2dHZ1dpM09lZTNHM1o2aE9sQ2NOaWFXdjNRWW5WRXJzWW8raVZ1?= =?utf-8?B?dkpTeTlUclJ3dkRVc3BrSC9BMDB6UkU4VUhDeDVqdDFWdmpoOTJaK2ZJRTFz?= =?utf-8?B?Z2VmYnlRd0hZTStkbTdWWG9lSnNYMjI2KzNGbEFEa0ViWUlkRjdURkVTektQ?= =?utf-8?B?WldpOWZXeTdxYXdMK2kyTlR4a1dUTDZjNkU1SVZaWHBDcWxpMnN1MkF2aTI5?= =?utf-8?B?aHphOUNqSG95cmEyWFpGZHd0TTUzVmNYbkJ1eFNVNXB6Mjd3UFVZMThYOFRa?= =?utf-8?B?bFlGMTlWMmJGYjR3UnN0d3J2TmZvUmgybUZyQUhLVUpNdnE5UHdUd1ZxSXVF?= =?utf-8?B?em1abDhWaTlFNTVTMFNoYkJ2WG4zN0xUSFp6bFlmK1loS0Y4ZXk4VHp2TnpV?= =?utf-8?B?QWpXTGRad3BJb042Rk1lOUlXQ0lhbmRhV0lPSmQwUkxodFFsRzhrSFgxajVX?= =?utf-8?B?MFhvQzVFYlRTK1c5c2FuYUtkWHI3Ri9EVGZKTEJ6amdReVpUbmtmWWwxZk5W?= =?utf-8?B?ZFd4RVNhVlZadm51REtZNWI0Wmd3emxOSkFCdWthTlcxSkNCTXFNdDZxTVl2?= =?utf-8?B?T3NWY20raXgyUVFIUnNMT210K0d3MWlWbEUzUnFtZVhmMEtwNmVOc0pRVits?= =?utf-8?B?MDZVR2x3cndoQmtSWGxnSUpjbGZJR2Y1U1hrMmJ0RjBqNlVOQ2x1b1RMWVlO?= =?utf-8?B?bk1CV09yeStjaSsvVWl2Q2kreWEraUxEdy9wbktBUnJoaWFWK0dOUFdBQ0lp?= =?utf-8?B?bWdhdXlIT1RTbzk4ek5GaDc2aFFIaldnamRPTjhYZGFOVnZJUWRWenZka3Y0?= =?utf-8?B?OVpCMCtwZU56aDRGNDBUeHoyNWxTVXdUclhqa3cyRzlzNjFIcllMOWd3eUJa?= =?utf-8?B?WFZ0dFA1TUJTOWo1RlNEK0JBbmhnVFpCWURhV3VHK01TcmdGOEI2TjNpVGdk?= =?utf-8?B?NDNjWjRidnJjNkNtbkhHVmlGNmJyemUwL0dPZjRkSnBFR252ZTNLZVZabWN5?= =?utf-8?B?d0EzYXhMd2lLa292elFKTFVyOXRhek8zVWtBRzBNNUYvbGgzL3Vqc0w5cWQ5?= =?utf-8?B?Qzh4WEwwZGNuRThHZ21JNDhybnVyUWRqbERUNURoUm1jZm5RZlJVcGcwdGhr?= =?utf-8?B?eERyZkdBdjc3MFIwSlpCcyttMkRvZm9KZnZCY1cxNFM0Q3JCdStNSEJXVE1U?= =?utf-8?B?YUI1NjdYSjFzSW9xK05LRUFMdXZ5aHgzcDFuc05RZjgxdngweE14bDdBVVdT?= =?utf-8?B?SmRtUUc0a3p4cEpKSGhjdlppMmcxcXZCOUlBbEo4RVhFc1M5VXVBdEtUQ2Vu?= =?utf-8?B?UEE1ZHNNa1cwY0VYOXVJRTY3MHFKQWpOU21pMlVST3VsNXBVdVN3QWI3M1da?= =?utf-8?B?VVgyc2x1QjQvUmtmVnFCMDA0M0xGVFFCQ1E2MzVxdXVlcjhFalZoNlE5alNm?= =?utf-8?B?bkRHanU4OVZTaDNCRyszejBxWG4wOEhZRWpzWE14ZkE5TElOVzBIeTVRdFBS?= =?utf-8?B?bHpNd3VLdWNkR3hlNHpVeHlyOSs1bjJtUk1RZlpLaDRNS3dvbmJWcUsrYlpk?= =?utf-8?B?aFBIRVJXQzltV0tKVXNSaDhXbVd6Wk9neUNMQTJXWENCSlVrUHRJUlBjTDFP?= =?utf-8?B?YU0xUE9UN0dPblBhT2l5d1ZBRFJRR0lHalNLVVZoNVNTQk1sMERqekw5bG02?= =?utf-8?B?Y2paMzFtYWxyeG1kTkY4MFhlZjg1UmFZbUR2L1FQZkpTQnZneDhxZFZndmNM?= =?utf-8?B?bUwvNVlmdHNkRFBRaFg5c3B1RTFGS1JCOFUveVhEc1FKdk5tVEw0ejFuK3BB?= =?utf-8?B?YkFZTEIwZFlEbHBDV1o2dSttWUgzNVhpWjduK2wzc1B3cUVKUDhCcUxCTnF2?= =?utf-8?B?TzlibjQ1OEVVRzdTcEdlTkR2ZEVhcVZLbGFJb1dMTmRsb2ZYSklhVlBJZ2s0?= =?utf-8?B?ZXhBaHdJdGZOc2YyMHN6REhIRTBqZ2xIQm16TFhvcitBVUYrMTYvcjZUSlA3?= =?utf-8?B?ZXk1NHo3d1c4cGhBQ091MGhBMElNeVM3RUNIT1hCeG5WYW5xaldrdFJwU3Z0?= =?utf-8?B?MDI3UVd0ODAyTENVb1FrT200ZmVXU091RHR6M1Z2R2dUcTcxT1JvZG5zSzlB?= =?utf-8?Q?mPlwv4PR3AXBIfAyaKKfU2s=3D?= X-Forefront-Antispam-Report: CIP:165.204.84.17;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:satlexmb08.amd.com;PTR:InfoDomainNonexistent;CAT:NONE;SFS:(13230040)(376014)(7416014)(1800799024)(82310400026)(36860700013);DIR:OUT;SFP:1101; X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 23 Jan 2026 16:48:37.3009 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: db7c948b-e339-4995-365c-08de5a9f4142 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=[satlexmb08.amd.com] X-MS-Exchange-CrossTenant-AuthSource: SJ1PEPF000023D7.namprd21.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: DS0PR12MB8413 Hello Vincent, On 1/23/2026 9:28 PM, Vincent Guittot wrote: >> If TSC / any potentially unstable clock is marked unstable before >> sched_clock_init_late(), we never flip __sched_clock_stable. >> >> On x86 side, since we already start using TSC for native_sched_clock() >> super early, we have defensive measures (and a __use_tsc static key on >> the x86 side too) to switch the sched clock back to jiffies if we >> realise TSC was unstable before we hit sched_clock_init_late(). >> >> This is necessary since post the sched_clock_init(), >> "sched_clock_running" is true and the local clocks will always uses >> sched_clock_noinstr() and it must be switch to jiffies on the x86 side >> since arch defines it. > > sched_clock_init_late() is always called so can't we check if > irqtime_enabled and clock is unstable then we disable irqtime > accounting That can be done, yes. Wangyang, can you also consolidate the irqtime disable bits (TSC and generic) to trigger at sched_clock_init_late() if the clock was found unstable and in __sched_clock_work()? Both context can directly do a static_branch_disable() without needing an extra delayed work. -- Thanks and Regards, Prateek