From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from NAM11-BN8-obe.outbound.protection.outlook.com (mail-bn8nam11on2043.outbound.protection.outlook.com [40.107.236.43]) (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 7C16B17995E for ; Sat, 15 Mar 2025 23:15:34 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=fail smtp.client-ip=40.107.236.43 ARC-Seal:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1742080536; cv=fail; b=HbVr8rD2OZoDky1+lKTA1gv+2tMR9IWQXZJvteEUj0tjvbxur4e1hL30kTrfWlWe37zYnYUFvclMRsZK1D+34dvRxlKgUVn31+Lpp7TQ3vqsnO03CxkBVYY4MWa8Lo5b49Z9gehE81V30X4kolfbi9jfgQFpgfC2uJbpNc4SRaQ= ARC-Message-Signature:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1742080536; c=relaxed/simple; bh=Yv2pNIwDH95nM6ePMnZ3elctiI2YpCxQz+jxxpTkRAM=; h=Message-ID:Date:Subject:To:Cc:References:From:In-Reply-To: Content-Type:MIME-Version; b=RlO2Nmj74cpUiQboNpyhz8RxSgHzVpq6JPMUFZsVG6HQkqYrolDmmYR9aL/aWGNwgYsEKDjyBku+hCnZX3FRXA5ZujACzHAG1ET0vxbaqGMgvqh2OytxoXHeV9dpNZOd+3a5K5IhIpG52+gkKeHfEJ6kDTrLTPFAqjgdTlpl5K8= ARC-Authentication-Results:i=2; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=nvidia.com; spf=fail smtp.mailfrom=nvidia.com; dkim=pass (2048-bit key) header.d=Nvidia.com header.i=@Nvidia.com header.b=j0ogjuL7; arc=fail smtp.client-ip=40.107.236.43 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=nvidia.com Authentication-Results: smtp.subspace.kernel.org; spf=fail smtp.mailfrom=nvidia.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=Nvidia.com header.i=@Nvidia.com header.b="j0ogjuL7" ARC-Seal: i=1; a=rsa-sha256; s=arcselector10001; d=microsoft.com; cv=none; b=jJbDiVF7hrZ01Nh6pos0ToUdKqBXtkqWb0V++HM1JFW2K2wLEBzP/7DCfzNYkCZmp/MGjOmCWaxy/Fi4MHk6A/rJHklzix7pJjPehcr69ybZFsjD22xjtWjsXQb6IvYALlYC1bz5IgdPFwhyKhbDeipe0Fz7QMU9SL7D2uH466cJKqdUki2UPNbiM7nnbv5g4s5NRN1HPtgDNE7JnhN/7UHXA9mKjR/0KdJfOxF+lIAmDOWEOSmz4JMbwIe5acBy+c/nybKKubrVQNPL5K1Lg0gXW95WFVsJvY6PkYPAZZPy97iW3t3N66+EJHXqe3+xtJMfQtIqvJ/tZ2FZ7i/xxw== 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=grxAUTofk4VjzqdIlONv/usIvmvlH+de9nVFAVJ80zk=; b=f6BjnQpMDhZ1aGkClgL5hkAFgYh6VhazWeYFmENZffMEkdh9K9AIcaEORRyzks41nL7p24VgZZ8Vtl4NnWXDV2LZ5OoJRpAu4eQMc5/WJBAI5MyvbiFO/ico6klDiGYzraqRxPEGVn+vCynhgTuy4Fq5D72ivfyNtH9rkdnBFwavPKpE/bU8s34b8FRSR/Tz3R2AAhon1qWKDz+UfhbicLccixSakN93+fbNRsRoLKaYlsKwD+T5c1lp9LulS5SzxFqDJkioC5NyFaI6bDRbVc0QltHgVgIkw2Tdw+2gO1R7DTWrKI+dwvPyCrd4Djze0tr976Mu2x1HkuuhMv+tMg== ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass smtp.mailfrom=nvidia.com; dmarc=pass action=none header.from=nvidia.com; dkim=pass header.d=nvidia.com; arc=none DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=Nvidia.com; s=selector2; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=grxAUTofk4VjzqdIlONv/usIvmvlH+de9nVFAVJ80zk=; b=j0ogjuL7AafT/9uYSe0+hN6oaFkR9NzS/XT9Rmvoa8UqrqKa+L5q7xqG38+5iJ1aFp4kiUoikCDnqqYDwV+Lxw5fylGDsQi/zjvm+O1BpDnddxWDJG2ycwbZV27p3vO8HN0HOH7/Fj3Th0ITftiI6A2bVKTaxLgbYQGjby3yBkCi3nQmm4K5wUEL+N2iX4Nj3/dC4BSQBHaaV5fMVHRq6vOH/VX1Nepl+88dfyECncN816h1ERUu7YAc30mdEApM+dffYoMyxFv62gfszQ0Z692+NawQ6FJNTmIOB53p7g9pxV6vVF5yCp71JvwkmVB2qdhgqmKkrQ1Yh45P4gYkug== Authentication-Results: dkim=none (message not signed) header.d=none;dmarc=none action=none header.from=nvidia.com; Received: from SN7PR12MB8059.namprd12.prod.outlook.com (2603:10b6:806:32b::7) by CH3PR12MB7740.namprd12.prod.outlook.com (2603:10b6:610:145::8) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.8534.33; Sat, 15 Mar 2025 23:15:31 +0000 Received: from SN7PR12MB8059.namprd12.prod.outlook.com ([fe80::4ee2:654e:1fe8:4b91]) by SN7PR12MB8059.namprd12.prod.outlook.com ([fe80::4ee2:654e:1fe8:4b91%4]) with mapi id 15.20.8511.026; Sat, 15 Mar 2025 23:15:31 +0000 Message-ID: <3b244939-6d55-4d86-8b77-a9a7629f8239@nvidia.com> Date: Sat, 15 Mar 2025 19:15:27 -0400 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH RFC 3/8] sched/ext: Add a DL server for sched_ext tasks To: Peter Zijlstra Cc: linux-kernel@vger.kernel.org, Andrea Righi , Tejun Heo , Ingo Molnar , Juri Lelli , Vincent Guittot , Dietmar Eggemann , Steven Rostedt , Ben Segall , Mel Gorman , Valentin Schneider , David Vernet , Changwoo Min , Luigi De Matteis , paulmck@kernel.org, boqun.feng@gmail.com References: <20250315022158.2354454-1-joelagnelf@nvidia.com> <20250315022158.2354454-4-joelagnelf@nvidia.com> <20250315072225.GG36322@noisy.programming.kicks-ass.net> Content-Language: en-US From: Joel Fernandes In-Reply-To: <20250315072225.GG36322@noisy.programming.kicks-ass.net> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-ClientProxiedBy: BL0PR02CA0037.namprd02.prod.outlook.com (2603:10b6:207:3d::14) To SN7PR12MB8059.namprd12.prod.outlook.com (2603:10b6:806:32b::7) 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: SN7PR12MB8059:EE_|CH3PR12MB7740:EE_ X-MS-Office365-Filtering-Correlation-Id: 6e9a7010-7c26-48e7-fea6-08dd6417481b X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|1800799024|7416014|376014|366016; X-Microsoft-Antispam-Message-Info: =?utf-8?B?QnB5OVlGU3J0NUM5SkVaUkNUaFpmS29RREtWSHpHOEM4OFhoaTRkbVJ5U05y?= =?utf-8?B?Um1mQkVjMWFIcVNGU0tUKy93bWFIZWZId2xwcFlPTHovUktvUkIwV0o3SVU4?= =?utf-8?B?WG1uSU5mUFlwekprZ1JXcGVMT0tRZG5zY3p2eWU3TVRTVko4N3REV3h5U1pY?= =?utf-8?B?WHgzTnZYOGFHL1JKOWNESHF0K2p6SGdIZE5sTkQyZlVldW9YV254Q0QyTmRq?= =?utf-8?B?cTBuZWF6Z1RnSENqcHRDNGVuWHErZGVOLzZ2eVFPTWF4SFBScEhacDZMelgz?= =?utf-8?B?SWFORTEzWnNhakc3MDJocVpXM05TR1JYNXdlWDV5b20xUVQ5Z0ZTNkhsMEVy?= =?utf-8?B?bkE1WFJ0S2E0WTBSamFtQlFiM0dxV1pYWm1JZzRFajh1aFF6VkdINE9Jak1o?= =?utf-8?B?QmswUVpOeHM4WmVJWmZhMTVkN3kxQjl4aUJVZFA4NStQZGhOZmVDQkIray9N?= =?utf-8?B?dTlpVVJwQnFxOSttNlJ0aHhYL092S0NOYjVzb2ZDWXVpQjliRFhQcGM3WFZq?= =?utf-8?B?cXFYUjJLWTMxNEU3T09TcHc0MjdNWGVBa1pyb0xmQ2gxRWlKczMwUlJqMHBY?= =?utf-8?B?bE43YmxLQnVjTXZKZ25qTXo5RTA1dzRYTHJOY09tNzF0QmxhZ2Y2WVpFZnVv?= =?utf-8?B?cVJjdXlhb05JNmRjSVpUdnY2a3ZqVDZ4NGhTUGlSd21KMGd5bXd6cUcrWml2?= =?utf-8?B?bEJ1dGwyMExtakVBa0xjSWhtYUZQOE1La0p3L1JqQ0t6dGlLRkU0QXllNlpn?= =?utf-8?B?RE9OeWppd0VETXFHS0Y5ZkhGMlQvVFlCbHlld1phaXhUWTlQMGJBN3hjUjJO?= =?utf-8?B?T2o3WTYxS2R0Y0dneXRSYVo5Q1M5UzlGUU9sdWVjZWV4OWlnd3JmT0NtTDBN?= =?utf-8?B?blJuZ3RvVTFCWDQ5VXVla0dsT3ZhQWtURGdjaDJGWjFQTkhWODg2RGJncEhR?= =?utf-8?B?OGU3Y3U2eUhZMUpqU0pic3pveVd4UFkyWVlxNzYvZFA4MHljZkxPVE15aGxu?= =?utf-8?B?Sm5wOG1uNDRGYVRFQnNla2M3RTZ6UElLK1RwYituNEdNRmFqUGQ0djBsUm05?= =?utf-8?B?a1plc3pWcGVibEhkUmJBVFJla3llVGE5TklXUWU5bWpzTTlCbU8vamdSVEJ6?= =?utf-8?B?bVdZUGhHSzFVODNvekFUcFVFaVVJclZxRkNqZGZxVC9IeEtMYWtaMWZNZ0J3?= =?utf-8?B?M1c4K2hyNVU4VGhiWlIxTndpZlkrYkZUTTVka2o5NzdFRmxVVi9JT0M2OXBP?= =?utf-8?B?YU5QcVBqZ2FkcHVSMmg5Vko3dktNbHRMYktzNi9Pd1l1NWhTc2U0VXE4dW9J?= =?utf-8?B?M0xacVQzc2VuNlpGWDFEa3lyZXBwNmF2a2JXUnVIekxTUEFmU010TURLSkZT?= =?utf-8?B?UktSZTl5VEM3Y0lkQjFpQ0tLdnZkRmtlYi9SeHhiVTdPNHllZmNtb20xMFYr?= =?utf-8?B?UEpuSXJCajlRSWg4NHFZUXhGdUxaanBkRE9Dcm13bkRyUXZ1NnA1NnpqTUdq?= =?utf-8?B?UmhtVFNPME9kMlQwak03YTlHUFcwaWZPZkpUc3R4THRyWGQ3RHpSSW1pdmd2?= =?utf-8?B?UjJCbW5VRDhoRnc2TUIvalNwcWZQNXJOWms3WUs0MFlHaTBZY043WTRpK0RY?= =?utf-8?B?VDZlelVJeEZFZjNmRjdzcVB6bkNoQkxXUlBqTUpEZ3hDL2orWHBjb0pZWjRK?= =?utf-8?B?a1gvUzU2NTNDRDVCalRETWQ0ek9UK3lJc2sxR3JRTnplY1RiNm42WEVnNmJU?= =?utf-8?B?dy84a2pYMWVtZnZRem9wN3pRTWViK2hlYjVVc0pocnl2UEphekF2Mjd6YTZ4?= =?utf-8?B?UEsvWHNwbC93ZXFoQTUzUGczTllKUU9vY21aMzYwZXZYeWkxT0FON0lkT01Y?= =?utf-8?Q?xm4hnKkrXpptk?= X-Forefront-Antispam-Report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:SN7PR12MB8059.namprd12.prod.outlook.com;PTR:;CAT:NONE;SFS:(13230040)(1800799024)(7416014)(376014)(366016);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?utf-8?B?Wkx4M0lvSERydmlSbzk1cEV6QjNCUVpqL1ZUdGdvdE5SbU5VTm9OVWFMb2ZP?= =?utf-8?B?Zm5VdnYvUUh1Z01Wa1YxaE5vcWRuUytYdWxKMUZxRlBPVjJrZ2FOQnZXcjhL?= =?utf-8?B?MW82YmRyNVpkTkVYVTV4ZkVHNEJOSk41VFhockQrWVk0S0tWMy9CTDlSSTY1?= =?utf-8?B?NFZzZlhEOVBJVGJVZS9ESEFNWU83dVdVZS9aM1dFeXVnWFJWbmpIcVJRTkJO?= =?utf-8?B?dEpMWTZoTHp5cUlGMXdpSlV1biszbjdnbnYxVFlNZ3ZzeTJKYnBMSys1V0wx?= =?utf-8?B?VlZIbWJqNTdCOXo3L1hFMnZHaTRuTHByMXUrSE9YOS9HeXREVTFEdERCbWRZ?= =?utf-8?B?RERhL3dab2NPMThoVHNFSXZlNmNkWWtLSGdsTjBoTGdNSm1PMzg4VnRYeFpx?= =?utf-8?B?MXNIYUxqUDFlQU5LZGE0SktubWtGa0FpQzBzOU5DVzhOck5nMGtMODNjSG1I?= =?utf-8?B?c1ltQUpGOVVBQTF3c3VsSFlyUTN6eVBmL2N3OW1aRTgvZnIrVHQwdWZMVFhM?= =?utf-8?B?N0dGL2kyUTMra1RQR2F2UTRNSDkzUWY3NUhialo5NlB4bkY1TU5IRkk2cy9T?= =?utf-8?B?TVBqU3Z4NGpJeUYydGkrc3ZWRFdnRVNyNzdxVkRwT1ZKdXFXLzdlMVdCdFJa?= =?utf-8?B?NWxTNXd2UDZEaFA5N3VFeUJZQkxaaW05bTAwRHhYTXExamhaRkdBSGpLUERh?= =?utf-8?B?TlRHcXJZUjlIekNHeDBmanV4RzlJTGFXcXRYaFJrSTJscHVnOGt1Z1Bxb1pU?= =?utf-8?B?ZHVqQ3BNZlNNNzBidWFyUGdDUkpvbXQ1WkJsc01UMkpqUEVFYndTMzJ0Q3h6?= =?utf-8?B?aTdKTUQrNVhvNGFrZ056SmNaVEdMN1lsbndiRTVRWWJkeVZ5R0c5Q05PTFZk?= =?utf-8?B?aU1wYzlFYlI4cFpHcmFLMmRzVjBXcG5VZzVrVkR2SEp2VHhUWDdQMGNrN1NG?= =?utf-8?B?WVBteE15RHZGSTZkTGNxcllpd0VueFB0N1BUelJlOWVtNXlrL1hTYWdDUUFV?= =?utf-8?B?RjVTK2JlT2dwbFhkbThKYlRLSUovNEVYS280bVk4NlFEUGJGV1czSkhwRzBJ?= =?utf-8?B?RDV6eGJPS0wwajZoN243Uno1QkRtYVNoUHVBelpWTmVhWFQ3cG5FYlBqZ1hF?= =?utf-8?B?SlovLytweFl3Z2UyUFhtZnUzU3ZXMlB3N2krWWM4OVhZVE9ZYVUwSkFVMlZi?= =?utf-8?B?Zm9qSGp2eXlhTDI3TGVwMm80SDBIeGJjMnZxc1FOMkNiZUZnMjRDRTlYSEcw?= =?utf-8?B?VzZjSllMYmV4MXZwRFVPQncwV1ZURXpSME5kNS9KS0FDbDdDWVRlTCt6ZWhw?= =?utf-8?B?dmVXcWlUQ3dqeU40WVpFb3VUSnVjV0JSQkdVY01GZVpmT3JXNWNuYkthM0Jm?= =?utf-8?B?bVRpdkg2d2ZTRENibTlSYlhGY1BjVGJwL1RtdEgrZWtXRFZIRThPYW1ySUJZ?= =?utf-8?B?QVMrbW9oL2J4OXFFTkgvMVBWQlZOTnQ4Y0xqUWpsMXZKY1EyYk80dDZJbWlE?= =?utf-8?B?SnhydkpMZWpNWWRFaHVqbTZBNXk2VVRWM0NLRitUNzVUWUNPNGxIOVNSVVg1?= =?utf-8?B?SE9IdkFvMnI4OE9hZ3JDd2xnbk9sVTFJQzliRHM0alF5WE8zU3pRbzE0Rzk3?= =?utf-8?B?bHBWckdqTi9WOHBCY1pKdUd2RHg5MzBtViswc3d1VzMyYzVLZ3FoOVNlbVpG?= =?utf-8?B?bWgvSlp0TDJpZWZ5cHExKzFCeFdxdElRYzNRZkwrdEV1QWpyVmJ1eHZ6dGlV?= =?utf-8?B?dWJUZGVZby9IOFZnRWRTK2dyRGl6YmplR3FZMWZCWFNLc2xWNllUS3pwdVhC?= =?utf-8?B?dkJSVkdiVkxXbWIyOGJPVnA1SzNQb296Qk44M3dkTHYvdFNJSjQxNHI1bWFl?= =?utf-8?B?Uk5ud0hiM00rcGd1eUJ5L2w2dktEbWJOOGIzZGFURloxa0crZ281S2cwODhr?= =?utf-8?B?WkQ4UWUwSnFTdXFLU2tCSFJpcnJnVjUwbC9nd3ExSFhNSnAzd1RMdnlqWC9t?= =?utf-8?B?b1JrRVhJQkpUSnN1NmxCYTFXdmZDZG9tQ0NqeTlQOS84Sm5sRGdJaHFibTFk?= =?utf-8?B?TkVYZklOSFlIS2FDQVl3bFRVTW1vbG5NdXVZZjk0YVN5RThBMEM2OEJpbUhX?= =?utf-8?Q?DEfBTyGnB5RsWJS7vV+bDUGTZ?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: 6e9a7010-7c26-48e7-fea6-08dd6417481b X-MS-Exchange-CrossTenant-AuthSource: SN7PR12MB8059.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 15 Mar 2025 23:15:31.5159 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 43083d15-7273-40c1-b7db-39efd9ccc17a X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: brL9+UY7OYp54OQJcUK7KlcEQs/PvevvKqhd+UwoEkP734S9xdSoheBpDl1TKklYxcQEPrXwOmVsm7Sd3aWfeA== X-MS-Exchange-Transport-CrossTenantHeadersStamped: CH3PR12MB7740 On 3/15/2025 3:22 AM, Peter Zijlstra wrote: > On Fri, Mar 14, 2025 at 10:21:50PM -0400, Joel Fernandes wrote: >> sched_ext currently suffers starvation due to RT. The same workload when >> converted to EXT can get zero runtime if RT is 100% running, causing EXT >> processes to stall. Fix it by adding a DL server for EXT. > > This needs a lot more words on why you need a second server. Because I > don't think you do. Sure, I will add more words to the change log to explain rationale. When you say "I don't think you do", do you mean that both FAIR and EXT could be served by the same server? If so, that will not handle the case where the system has both FAIR and EXT tasks in the mix (EXT has a partial mode where certain tasks can be made EXT with certain others left as FAIR) and FAIR runs 100% and starves EXT. We still need bandwidth allocated to EXT in such a situation. So we do need an EXT server. Or did you mean something else? thanks, - Joel