From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from NAM12-BN8-obe.outbound.protection.outlook.com (mail-bn8nam12on2089.outbound.protection.outlook.com [40.107.237.89]) (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 3E59D23643A for ; Thu, 17 Apr 2025 11:10:58 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=fail smtp.client-ip=40.107.237.89 ARC-Seal:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1744888261; cv=fail; b=GsvI3hz20qw/gsZLMhcgAa0gVPhB/MraCl+oYkRgWBQ1crm3kgfUV8qIEHXCgadECDrGuRF8hz95TdjoQULXzCFeC70vz/ioYOfN7vMshRLLS1c0CyM5kfwMWUIiUIFATsr/zqgF/0oM3UY4FSuoIxI2Q2woCOVAOM0cfhyWW4E= ARC-Message-Signature:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1744888261; c=relaxed/simple; bh=7rZfFkpcBd8Iv+b4jbuXWY+7Bt7Wj9N+V4VNxaeFvv8=; h=Message-ID:Date:MIME-Version:Subject:To:CC:References:From: In-Reply-To:Content-Type; b=tUM6u23QVLQhlAAwZrIN/Wj3VjhAzQRcZaOhHM33n/ssPVEwUe4RXBgVYIB9kWQ2Q5GVCpZIVGPpIJ2aoc22yOYjO4z+YDm3lFXs19Wmzkb0wedcytBrDVBaEtIhcCaJXnVf9erbLPPQZEMVWJ23NMPxzlNzy4BmjU0JN/F4DO8= 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=oHpnPVRk; arc=fail smtp.client-ip=40.107.237.89 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="oHpnPVRk" ARC-Seal: i=1; a=rsa-sha256; s=arcselector10001; d=microsoft.com; cv=none; b=qfwXlQXCJYoSmwg9qVdUpwEhCIXiWI3v6zGibWLzZyJE/aOTo99GOzVgF96/EzWHvux3lxdfT3Yf8wQzgeHbj4apSWmjp7qUklk8mcc2Tc8x0/mVYzP2pyD6eBdOQsuT3a8tKkQmJw4IqK6HVIFj8vPoWZ7pmLsH9eeHzijIBjN6nRHtj3ozJDppxExLiOhERTyp2ntDiiAKhXfGuARw42kviL9pi1Qc8pP6cXyLMmGSCF52kMhjRgyR6xB5NCDL3uCqoMDeEEtw3TCZA+F6uIOHGK18YwGXg3mcM0VyKz2GlqmLXLHd/BRAxw22X52kqgAzhIFW/Q7uSFWn398UuQ== 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=OQKXt6QcEKBUL+okgbyJKoRICZt3J6VoRLYOvuOsEDQ=; b=s3J3AKH4ZfOWqpk+nlpG2XdSsj8/lpW9QHL38hPuvLLKllzaKCdqwjRMgFy4CEYpWZPMJ3OljWgBEXvJovfVVe9dnsEBUNGmYkjXsL7CxAWCQ/gVkoYHnliHLrOJYBPEBrllEu9NXgs6DsJ0wSOgfx/VPEkxiakYfmbt6JXMntUr97wgun6G+Y4IT14o9ZfwW2/Ux2QEU9vKNdrN1eNCHLOrSwMwCAaESoTgcO69zl9qMDW4RMlddRWlvoA5CgjCcTBdnBWJdfSO3MBLn4/W5LEMSHhs5Faw2KZZnVgeQkLhqxqsf7WvPGyVZOR3M9egZa2gxvsR340Uejc7NTvaIQ== ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass (sender ip is 165.204.84.17) smtp.rcpttodomain=linux.ibm.com 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=OQKXt6QcEKBUL+okgbyJKoRICZt3J6VoRLYOvuOsEDQ=; b=oHpnPVRkQ3RGaSEv8QomJph6r0A6uLa5QQyHebGxEq/7acAKundlg+Qgw3Hvxg8Uk64WMvoEnXwo5ND79tAQ46Xku9PGOf3d59H0Ib+Abaut3Xk7jP4b4qWNt6N2eSg8ataUnj/kP5Kk79sVF6CDgneUdmepIclJ11Mx3yu95k8= Received: from DM6PR02CA0160.namprd02.prod.outlook.com (2603:10b6:5:332::27) by BL1PR12MB5779.namprd12.prod.outlook.com (2603:10b6:208:392::9) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.8632.29; Thu, 17 Apr 2025 11:10:56 +0000 Received: from DS3PEPF000099D4.namprd04.prod.outlook.com (2603:10b6:5:332:cafe::bb) by DM6PR02CA0160.outlook.office365.com (2603:10b6:5:332::27) with Microsoft SMTP Server (version=TLS1_3, cipher=TLS_AES_256_GCM_SHA384) id 15.20.8632.36 via Frontend Transport; Thu, 17 Apr 2025 11:10:56 +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=SATLEXMB04.amd.com; pr=C Received: from SATLEXMB04.amd.com (165.204.84.17) by DS3PEPF000099D4.mail.protection.outlook.com (10.167.17.5) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.20.8655.12 via Frontend Transport; Thu, 17 Apr 2025 11:10:56 +0000 Received: from [10.136.45.107] (10.180.168.240) by SATLEXMB04.amd.com (10.181.40.145) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.39; Thu, 17 Apr 2025 06:10:53 -0500 Message-ID: Date: Thu, 17 Apr 2025 16:40:50 +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] sched: Skip useless sched_balance_running acquisition if load balance is not due To: Shrikanth Hegde , Vincent Guittot CC: "Chen, Yu C" , Tim Chen , Peter Zijlstra , Ingo Molnar , Doug Nelson , Mohini Narkhede , References: <20250416035823.1846307-1-tim.c.chen@linux.intel.com> <667f2076-fbcd-4da7-8e4b-a8190a673355@intel.com> <5e191de4-f580-462d-8f93-707addafb9a2@linux.ibm.com> <517b6aac-7fbb-4c28-a0c4-086797f5c2eb@linux.ibm.com> <6fe46df2-2c80-4e2f-89a4-43f79e554f65@linux.ibm.com> Content-Language: en-US From: K Prateek Nayak In-Reply-To: <6fe46df2-2c80-4e2f-89a4-43f79e554f65@linux.ibm.com> Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 7bit X-ClientProxiedBy: SATLEXMB03.amd.com (10.181.40.144) To SATLEXMB04.amd.com (10.181.40.145) X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: DS3PEPF000099D4:EE_|BL1PR12MB5779:EE_ X-MS-Office365-Filtering-Correlation-Id: 0fac82e0-a218-486b-5174-08dd7da086c9 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|82310400026|36860700013|376014|1800799024; X-Microsoft-Antispam-Message-Info: =?utf-8?B?VmpkOWpxdGNiMmZLRXlKc0pQNDNDa0swdGNoTVFLMThtOW00VlYzVTFXZTJp?= =?utf-8?B?aFpGSHcybkhmUGVRc2FqRHUzN2p5VDNBNVVxNDcwOGhLaGdCRTFESmVOM3Nl?= =?utf-8?B?RXRuQml6RnR4WDJmWnQ2eVlZcmxRZ1pMRk9VL0pMb29OcUtDdFg5RWZmVllQ?= =?utf-8?B?S1ZIdzIxQVVSVGw5RlZsTzBDYmd6MUlwa3oyb0Uzc280OHR1S2JPVzQ4cHZZ?= =?utf-8?B?K3E2dGp3eE9SaWRTMEhkTGtjOEdleHpNUzVpZ1BmMktBRjNuRXNFWUdMRTMy?= =?utf-8?B?UFFFOUF4bWMveHlMMG56Z2dEb2ZaaEd5c0NhRVRFL29kd2FGdE5ERVNYME9o?= =?utf-8?B?RFova3NkNi9QWnRmOFJmbytMQXJra1dwcW56enh0NFE1Mm9Od0ZwRjJPbFF4?= =?utf-8?B?Q21WU29TY2RVTGdZN3pyWnBMYlllU2JScXZnRTlTYmFlSFNtN3Azbyt1SVVY?= =?utf-8?B?Q0JEZ1QzNHFKNDlFcjU0dWhOTzFuSENNTXI3dnV3OFdSUmR6RmtlbjV3cU1G?= =?utf-8?B?dUxadmNxRStkc0F1MUNxY251b0NLYTVLR0tmenFqU3RlY0g3OVl2T0Nldndr?= =?utf-8?B?M09QcXlhMDBGNFd5QlpRMUVrQk5QR1RhM3VxNE5tYnROSUp4SXhMWWk5LzBq?= =?utf-8?B?ayt5TUxRVkxMNFdjT3RzS2hlSU1RNFBBbUFJSzAzUUR2d2lZeFY2KzZuYkU4?= =?utf-8?B?enVVUCs2dE5RQTdndTU4S1hYUGtWRmhmczVSUWY3cEZ3TUR5MFRBRnFkdzJ0?= =?utf-8?B?Tk1jTnNKM0ZZeEM0SXZvS2hTeWtMOGg3VUZvVlI2ZllLamxIcmhtbUxUNGRL?= =?utf-8?B?Y3RLektEWlk0RThvejRkR1dYeEh2SVBGTHExRVB4R0NKZExGZFc0TEowY1VD?= =?utf-8?B?MGY4VG1GTmdwd0FOTk84M2Nia1VIeEplb21HZHExZTNYU2Jsa3Q5M1kwL25B?= =?utf-8?B?UWowWTdIaFNBaGs0WCtUUm5xeUNzUWxaRTFTNWpvL0JiVmZ0cnhzZ2xCWXB5?= =?utf-8?B?M3kvUE9uYXE3Z293d3NqVHRXMyt1Y3dtVUhtcGdkMmZCVFc4ZzFOcUlKNG9Z?= =?utf-8?B?SWJIOXo0ektsUEU1TCt1QlJkMHBCbmx1S2Z3b1dScGJHdklYc09Uc3BtWC9a?= =?utf-8?B?MDkvUnBpdUFraFc2cEI5STh5bTJpWENRUnFISG9kOERzTjFnVzZxSHRBdllv?= =?utf-8?B?YWRIVmpZcXBZcWJqV3Y4L0J3WlNuZThSWjVaZk51T0c2YzMxNXZ3bGE5Q3Yy?= =?utf-8?B?c0ZVamJiRy8xVUpFWVRqdVVxTXBibGN2YlZtWlhwV3VxTVlhOFpSL1ZlT3dh?= =?utf-8?B?WElTbis2MWJ2ZmlCSi9lOVJWQU5yT1N5WVRNZVFpS0dWek14U0lOcEp3eXRG?= =?utf-8?B?U2M4YkM2dE80dHRzdGtyZG9vZXdKUUdxMy93U3BLODBuYlV0dlBOREhyemdV?= =?utf-8?B?djVQdFJpaUNnUjZCN2N5VCtmN2Nuempwem4zZjlmVTFYTVZVSDRoNFp0ZnJG?= =?utf-8?B?akRvNG1tSzI0djRCcStkaDZZV29mMnpCWHk3TzlqWEw1ZTFVTlJBWFpiOGJp?= =?utf-8?B?RkFyRVBJaFZrNGx3RVJ4d2x1ejFpTWxVcElnWHMwYVdWYW0vWGd3UFJIOWVm?= =?utf-8?B?V3JyVlgvUjZ1K3llWlpESEloeWhaSVZ0dExqblFoTVl5bUlkZVpJNFN1c3FE?= =?utf-8?B?UGJPQStpTFIzYXgxak1sOVltWmV2WkNQaHdNYnV0cEFpd1FibXdsbFlhWVhm?= =?utf-8?B?YjhacnllbVlTMS9zMWdNVE5KSXVUbE5XS0NFTmpVeFFvL09jS1VsMFAvNTIy?= =?utf-8?B?RVVqTkkvTmwxZWR0TWZFNEt6Z3BwVy9hRTNMc25nNWtjb1dMVUhOUVZvTVNU?= =?utf-8?B?NENiQW1tL1diakFEN1hodmpWTE40QkJ6MTAyZmZZUlc3aHpvdGFYaFZnQWJo?= =?utf-8?B?WGdTazBBRzd1NWN5cjRlNTk3MmpxZmptTWo2S29NNFhSK05EcnJ0eWM2eE5W?= =?utf-8?B?K2NybFNuVndSWkNnS3QzV2JTSnV5V29URGFOZjN4UUVZbENOd2J6ZFdaWmp0?= =?utf-8?Q?Cv2Oon?= 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)(36860700013)(376014)(1800799024);DIR:OUT;SFP:1101; X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 17 Apr 2025 11:10:56.5277 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 0fac82e0-a218-486b-5174-08dd7da086c9 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: DS3PEPF000099D4.namprd04.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: BL1PR12MB5779 Hello Shrikanth, On 4/16/2025 7:44 PM, Shrikanth Hegde wrote: > Slightly different topic: It(kernel parameter) also resets SHCED_BALANCE_WAKE. But is it being used? > I couldn't find out how it is used. So the usage is very convoluted. SHCED_BALANCE_WAKE is same as WF_TTWU. kernel/sched/sched.h makes sure of it, with some static asserts. In select_task_rq_fair(), the for_each_domain() loop has: if (tmp->flags & sd_flag) sd = tmp; where sd_flag is (wake_flags & 0xF) This boils down to (sd->flags & SD_BALANCE_FORK) for fork (WF_FORK) and (sd->flags & SHCED_BALANCE_WAKE) for wakeup (WF_TTWU). There is more convoluted interaction with arch specific "node_reclaim_distance" that can clear SD_BALANCE_FORK, SD_BALANCE_EXEC, and SD_WAKE_AFFINE if a node is deemed very far to explore balance on wakeup / fork. Probably some of these flags can be merged now that things have evolved but it requires a bit of auditing before jumping in. -- Thanks and Regards, Prateek