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Tue, 11 Aug 2026 16:59:19 +0000 Message-ID: Date: Tue, 11 Aug 2026 09:59:16 -0700 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH RFC 00/23] resctrl: MBA control emulation and ARM MPAM MB_NODE support To: Fenghua Yu , Tony Luck , "Ben Horgan" , James Morse , Dave Martin , Shaopeng Tan , Chen Yu , Babu Moger , Drew Fustini , Vikram Sethi , Shanker Donthineni , Newton Liu , Gavin Shan CC: , References: From: Reinette Chatre Content-Language: en-US In-Reply-To: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit X-ClientProxiedBy: MW4PR03CA0028.namprd03.prod.outlook.com (2603:10b6:303:8f::33) To SJ2PR11MB8370.namprd11.prod.outlook.com (2603:10b6:a03:540::20) 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: SJ2PR11MB8370:EE_|IA1PR11MB7197:EE_ X-MS-Office365-Filtering-Correlation-Id: 066075f2-d785-4a02-4916-08def7c9e228 X-LD-Processed: 46c98d88-e344-4ed4-8496-4ed7712e255d,ExtAddr X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|1800799024|23010399003|366016|7416014|376014|11063799006|56012099006|10067099003|6133799003|22082099003|18002099003|921020; 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It extends memory-bandwidth monitoring and > control to memory-level MSCs or CPU-less NUMA nodes, and adds > documentation and tests. Just to confirm, I believe that [1] simplifies support for CPU-less NUMA nodes. Some highlights of that related to this series: - There was agreement that resctrl will treat each resource at a particular scope as a separate resource. Just like L2 and L3 are two resources that represent cache allocation at different scope, MB and MB_NODE will be two resources representing memory bandwidth allocation at different scope with the MB resource implying L3 scope. - [1] contains support for switching control mode between legacy and native. From the MB_NODE examples in this cover letter it looks to me as though MB_NODE will take the shape of a percentage based control. As I understand the hardware has multiple controls with finer grained capabilities and how these will be used may still need emulation if MB_NODE is planned to be percentage based. As a sidenote, since it is introduced after the new control properties it could possibly just start out as a finer grained control? - There is no need to change the info/ hierarchy on switch between legacy and native. Regarding the monitoring support, I still believe that the monitoring support needs to be separated from the resources to accurately reflect that the monitoring is associated with a scope, not a resource. This change does not form part of [1] though. It is fine with me if we continue discussion at [1]. This message is just intended as a summary of changes in the works that should simplify the support for this hardware. Reinette [1] https://lore.kernel.org/lkml/d258a32f-12d5-464d-abe9-4720fb3e44b3@intel.com/