From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from PH8PR06CU001.outbound.protection.outlook.com (mail-westus3azon11012044.outbound.protection.outlook.com [40.107.209.44]) (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 0CBB172628 for ; Fri, 19 Sep 2025 15:34:16 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=fail smtp.client-ip=40.107.209.44 ARC-Seal:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1758296059; cv=fail; b=iLTSE5JS2yV5l39Eeahn4GfF5USIsPqC+ebwcNrwyK9zeUtb9OVpao2EVqXS+8Pgg8ys8PrtZdmIH0hUyZJzGUNBbkI7kzYDneBZGxGHrXtFBGlu4UcNAs+98H1xOlde6+zT8MA69xHP/nv0v+L7xVs0VX3+fpti3mWZW/VIrPg= ARC-Message-Signature:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1758296059; c=relaxed/simple; bh=gaGLdInZnIPuGmPiZF21Y/KblgvIfntoJLE7cREwd/4=; h=Message-ID:Date:MIME-Version:Subject:To:CC:References:From: In-Reply-To:Content-Type; b=An3opp5LkDoALYN3sr1muPXSqa0x88Oj86QYaXY/GUbYGtiqXPTlxrAIcM5h+gY7SGz6rinwQrHbwz5J+MHnKbMLRXiGKKWr4lH0CCSWKuXZ2m8UMO4GaX+CYugDLLL6NVr0f8ib0PZy/9hONlojhFiq8sImym8U69DAykfgQHw= 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=QSMqGBbl; arc=fail smtp.client-ip=40.107.209.44 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="QSMqGBbl" ARC-Seal: i=1; a=rsa-sha256; s=arcselector10001; d=microsoft.com; cv=none; b=saAtzmp7ik/wVL4IP4YOHG3eCQAELaF2KDrRh1PZu1gJE4bzKeDbh4r17RuUYVTFyVezO7mRNdNv9JDHd6/+CNQeG+MJMGI2H9cU+n57pOdZxrYHKb0ZkmNj1RzHCaEEXy4Pdyf37IlO9yiXKleRnYs+/YI+K6AVJM2ddYHU+T06xm/zpmEMTIuQk+BOWaN8SI4qRdsP9rScD2eH5i64PIsxzn9obsPAKYYw2oLYOki+um5oxJl9NQ0He0PAyvCAHXtuFwWiKCWd7KbI3vLVygnO5j0GO+IPwEbaRWPKPFkmnJpd7Ew9xvmSfFdgakB1YsmOF5hFO2PAI7d36JCZ/Q== 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=7U3gR/yzK6Qh4wcQKrqPsWHjPMUUYejQIG3umTLoyrM=; b=e+Dpn289sVuTutJCOf1LlezQU8R8Y/iSZm9bKQS/IpaQE/75f/QkJMLb+jesrCq3qMqr+5zvqhB5Fmg4UCMq5GiSSZKdfLFo7CvvooGzyw8WetttkcgFmDULb8XGhPOKgXfZiv9f7fCKRAWm65MUEZoUpgJ4IlH2dsE0ijlfHOeu3Cc+zsUuwYRJkiEYEZU45kstwIpliYTMLDhUFa2EmHhvLFKcLXl3Cbw45ocAlZixPkYEY7X35Y9MB+gLO1Ydls5u31TVfTFY/tPiMt3fuhOooLzzwSr+Gva98sbhJyBc6M0maxFkonlrpwa35cLpdU2qVXqZZjN/UU/GpuOcGg== ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass (sender ip is 165.204.84.17) smtp.rcpttodomain=infradead.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=7U3gR/yzK6Qh4wcQKrqPsWHjPMUUYejQIG3umTLoyrM=; b=QSMqGBbls6qEAygr6KhhvEJmxRUhJoRjUaa738e0FyAA5YXOPg9TdvMRMqGj1NuxwoyopXt4H5C+PpeFmqMdLpayZvuMY1ZQWykL3BPL1pCgrhfiRxCoAdbIWWfforgEYSQ3kVALVNlpYF3varIN89mhRxNknb9P41PDDvnvAkk= Received: from SN4PR0501CA0007.namprd05.prod.outlook.com (2603:10b6:803:40::20) by PH0PR12MB8797.namprd12.prod.outlook.com (2603:10b6:510:28d::12) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.9137.16; Fri, 19 Sep 2025 15:34:09 +0000 Received: from SN1PEPF000397B4.namprd05.prod.outlook.com (2603:10b6:803:40:cafe::a3) by SN4PR0501CA0007.outlook.office365.com (2603:10b6:803:40::20) with Microsoft SMTP Server (version=TLS1_3, cipher=TLS_AES_256_GCM_SHA384) id 15.20.9137.16 via Frontend Transport; Fri, 19 Sep 2025 15:34:09 +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=satlexmb07.amd.com; pr=C Received: from satlexmb07.amd.com (165.204.84.17) by SN1PEPF000397B4.mail.protection.outlook.com (10.167.248.58) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.9137.12 via Frontend Transport; Fri, 19 Sep 2025 15:34:09 +0000 Received: from satlexmb08.amd.com (10.181.42.217) by satlexmb07.amd.com (10.181.42.216) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.2562.17; Fri, 19 Sep 2025 08:34:07 -0700 Received: from [172.31.184.125] (10.180.168.240) by satlexmb08.amd.com (10.181.42.217) with Microsoft SMTP Server id 15.2.2562.17 via Frontend Transport; Fri, 19 Sep 2025 08:34:03 -0700 Message-ID: Date: Fri, 19 Sep 2025 21:04:02 +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 3/8] sched/eevdf: Fix HRTICK duration To: Peter Zijlstra , CC: , , , , , , , , , , , , , References: <20250918075219.091828500@infradead.org> <20250918080205.716937764@infradead.org> Content-Language: en-US From: K Prateek Nayak In-Reply-To: <20250918080205.716937764@infradead.org> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: SN1PEPF000397B4:EE_|PH0PR12MB8797:EE_ X-MS-Office365-Filtering-Correlation-Id: c193ca0d-db8b-40be-3788-08ddf791fa0f X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|36860700013|82310400026|376014|7416014|30052699003|1800799024; X-Microsoft-Antispam-Message-Info: =?utf-8?B?aDV5WGl0TEFhS1h6d2dVbDNoc3kyUkk3bE9TSGRNbVo4eUN6ZENaN21OUFlS?= =?utf-8?B?MG5LL2RTY2F5Z04rN3dUQ0oxNUNSU05hQ0FKWUxWSDhkUUVkNGNDMlFKSG5S?= =?utf-8?B?ZHlUUFpkdmczUXBER1JnUkxiZ2l2NzJlc3hHNXh3WHBvUGFsUUthNHhkVEts?= =?utf-8?B?a2dKZXNyUUdudGR0TG1mMm42ek5SNVBXZ1YvYnhlYWIzV0VjS3g1c2NNWUpn?= =?utf-8?B?SURqM0ozeDc2WXd3Wit1S0tKVjBqcUZpVkYvcnM0am5taDNPMVg0aXpPNHpr?= =?utf-8?B?bmw1a2pRalAyRENMTWxnTFo4Um1EWURocngzdWxGNFFpOXZ4dWZnYzlRYStC?= =?utf-8?B?TlU0YW04MWNncG04eGRnMWRQTG5VT1kyVzQxZmpjL1BueWNBUmczUHJzYmUx?= =?utf-8?B?VC9NV01PNklnQnlmaWNaTGh4TXBnRElXWXhrMDhwczRYVm9aK0taWVhiR1B0?= =?utf-8?B?TmxwWExWK2FtL1JMRG5hS010OFFtZ1IzZnNrbTZ4TEp6L0hZME13VTR4SXdV?= =?utf-8?B?ZWZsSVp2ckd3bGJqUkYraG4wQTlGUEFjMUNEOU1BWkd0bC82ano4V3lWMFpI?= =?utf-8?B?M1B0M0FqMTB3ZVJScFFZRE5OQ0wvMnRBZ0tkZzhPcU1vazFZSGpqUnN4OTYw?= =?utf-8?B?c1lERUtTVHluR1RONThYWVJPQ004dnBtYzFWWUxldGRmRkVCUGE3RWs1QnE3?= =?utf-8?B?RDhpcXBXS2VLSG5ITnpjNlBLSWQ1NGlZSXY5YnZ1cjFQM0VKR1NMWjljcnRN?= =?utf-8?B?R0xRbWNrVjQ0WGszYnRrSHVXMElZMDZlZFUyM1E2SnYzOTl0Tm43RE5GeTJP?= =?utf-8?B?WXpJZ3FFeklrNzFOUSs5WHQ4bGVRbG5uTmkwaVA1eWlRY2NibThobGNENkpY?= =?utf-8?B?TmhYdnNja1JRSDNobmtObWZMTGxFcmFxeDJOYmxXVExNcGVoNVBrTGp0ZEk3?= =?utf-8?B?N1JYcHBEdHhWTVBURDZ6K3hyUHIvdHVQRVZaaU1CajI2ZHNicTA2VFdsalNY?= =?utf-8?B?RC9OV3pJYWlVVnBJdW0rMHlZRUNJSWdXOStsRWcwNWhZWksySXF5dnRUdXlR?= =?utf-8?B?VUZ2SUNDQkRtWUpZVzNLU000UnpocEZ6SmNLZVhDbWgrQW9wNHYxMUtoMUh3?= =?utf-8?B?UUw1RUdLNVVxbXhuMzY5VllpYnZWOGFNMDlXY1FCUGUyTndJdW9MbkgyUzZV?= =?utf-8?B?akdZWGhreDEzbUpjVmZEbUlkRUlQbk1seUI0bm1hbkRTRjlhbXZhUUsrZjVi?= =?utf-8?B?cFpOT0pDWTh4dGVVc3o3YmlPR2JvRFcrdHc3S0NMWDNDMFhSOWtIMmhwVHdm?= =?utf-8?B?VUUyVVo5QVNYMkFjTDZja0hRMFRvN09oT3FUUk0zelFwR2M4V2Z6eUFSSmJY?= =?utf-8?B?WnpUZzdlQ2RSRWlBa1dEOXZXRWpqV1p6VEczNlV0ZTBZTURPZCtVbHJZdzl2?= =?utf-8?B?anAwTjdoM2JWOVA1NGlWVzZDdWpLYVkvclNodVdlS0ZPUmVteWNKcCszcWVy?= =?utf-8?B?MVpWREhKZVRJRHl6V0N5R3hOWkMwYkUrN2RUclA1YWF3a2s3RkNzNkpQbGt6?= =?utf-8?B?V2ZZcDFOUlMzTVNIRndWOGJEUDV0Q1N2ckYvMllrcFRzNW03TnNkMXpOdDVZ?= =?utf-8?B?YXdYU2NhSUc4SzcrNkpkRmk5NVUxMi8xNXRaNGZmRlRWYUtsZzZhazYvWkRO?= =?utf-8?B?Z1o1WW1pSFVySC9NZUJINnMwZEJrMGZZdTdtM2REZVN5bFFVR1FWaWdhc0xQ?= =?utf-8?B?QS93U25FT0JHSTJZVkltcDdwcW9lZ0xWOTJzTC9JZ0FsWkNtR3YvUTJuc3Z2?= =?utf-8?B?MXVUajhMK3dYakxCRlFmRjlrVm1rZkJaRjBXbmpyN205R3NzcU51eXJ3K1NZ?= =?utf-8?B?MUJlbUdxbjdjUEdYY3lDWkdlakIzSmZ5SS9tMkN6WHlPMm90L1poSUpPQTJn?= =?utf-8?B?dmtkcmRlbFd2aTQ0ZExPQmQweDF4RmNYMTJCNFQyTE9Wa2haVjlRVVRHdkFO?= =?utf-8?B?MVBmWUpVRkptaitkWGNiL1QyaFVQMlhNYXZubW9oN2dQN2tSck9FVnFBL2Jo?= =?utf-8?Q?HEi9u6?= X-Forefront-Antispam-Report: CIP:165.204.84.17;CTRY:US;LANG:en;SCL:1;SRV:;IPV:CAL;SFV:NSPM;H:satlexmb07.amd.com;PTR:InfoDomainNonexistent;CAT:NONE;SFS:(13230040)(36860700013)(82310400026)(376014)(7416014)(30052699003)(1800799024);DIR:OUT;SFP:1101; X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 19 Sep 2025 15:34:09.3446 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: c193ca0d-db8b-40be-3788-08ddf791fa0f 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: SN1PEPF000397B4.namprd05.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: PH0PR12MB8797 Hello Peter, On 9/18/2025 1:22 PM, Peter Zijlstra wrote: > + /* > + * Compute time until virtual deadline > + */ > + vdelta = se->deadline - se->vruntime; > + if ((s64)vdelta < 0) { > + if (task_current_donor(rq, p)) > + resched_curr(rq); Why the task_current_donor() check? If the scheduling context has run out of gas, shouldn't we reschedule curr even if we were proxied? > + return; > + } > + delta = (se->load.weight * vdelta) / NICE_0_LOAD; > + > + /* > + * Correct for instantaneous load of other classes. > + */ > + util += cpu_util_dl(rq); > + util += cpu_util_rt(rq); > + util += cpu_util_irq(rq); > + if (util && util < 1024) { > + scale *= 1024; > + scale /= (1024 - util); > } Could it be possible that we arrive here from the dl_server's pick and end up inflating the HRTICK duration despite having an uninterrupted period for fair tasks ahead? > + > + hrtick_start(rq, (scale * delta) / 1024); > } > > /* -- Thanks and Regards, Prateek