From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from NAM10-BN7-obe.outbound.protection.outlook.com (mail-bn7nam10on2075.outbound.protection.outlook.com [40.107.92.75]) (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 9835610E4; Fri, 16 Aug 2024 20:39:00 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=fail smtp.client-ip=40.107.92.75 ARC-Seal:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1723840742; cv=fail; b=oztC5b/LbGRIwhowdiRCm49gSEbc3qsd2iIkMnHG8GAcbTlb0JJsv7TldKG8OFE08E+uRI548xAJsVq01/aNxPWZQCg8xBYuUVjRk9nSxml5bEKN1zb6gFGVLjXvMqRX7dkuZTad/hn8wtBxrKNAFO1QpbfRJbfgAxsJiYw5jfo= ARC-Message-Signature:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1723840742; c=relaxed/simple; bh=vGjv7AT1usjKAbG5uyYWC7vxRbPuhLO1ynU31s+QwVs=; h=Message-ID:Date:From:Subject:To:Cc:References:In-Reply-To: Content-Type:MIME-Version; b=VzplXCmX8fthUCjp65aiOK+64AZHIZJriaeXhInahhC8K5S8Sgs6TIn/sNMKA7HPOmEcl43nqFPOoiqm7S0RC5EHjqEenEBnf9IxPulXPVEyD2xoEzDyo4yzjAsoy7bcX+iaBog8XeFdSAxOx5LskMDh6QI1C7P0XsCwHX9Vy8Y= 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=wAFd0tYc; arc=fail smtp.client-ip=40.107.92.75 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="wAFd0tYc" ARC-Seal: i=1; a=rsa-sha256; s=arcselector10001; d=microsoft.com; cv=none; b=JmgvM3TqRlbf5zu/hHKmgBvUK8HV14xBQP9wwyackHB3CHTwNj5QZVrRKNNnnmG8Vm0gw05KyL/nWbrW5n6nJi1Q1kNvB1uXNAoahFO3qNX02qstGexnhD8cUzKLDWJFR79Hu0gVjUo/nGv096omGFUnWtypevetrqrFkV6xUD6KofHRhQbxJZipFA3lfxSE4mz9g8Ao7TWvRNjH1jjeoQkuT//7wKEaOEnarbT+DmMCuK0U2Z7a0UKZraU5r7ljfP6ZJHFzapFMk21hmaRVtPzyL1bi4jE1+ipD5tN9N3s7PqzQxlgK7VH5CzUZzWtXpptMUHJ25nreS5u4g8C4xA== 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=QO6BLaAaP7fMmNILhR4aj55jiQQUXgUl3RZJH0mkINI=; b=E9CGy79Z9cXj2mHgt7iPgZmjlyxY64qidd6T8YcIoNHp6JV7X2wxEsBN9Zu4bgRpu0SQkp2Ern9H9OaL9OHOas3U4776DfZknwXDudcJnt6Zz2y3Yk0nM4DvVTMXF9bl8wGJgkO8tcCpiVkvj8iK3FtyEd0yqhmkLce/iC899Jxi14JrCfPFU/O0xdcfd0s59XNk49dVXJ8oMOgoJEl8V33XnnFhS6AMIaNS3bgI3oXLADAJBGwoEhiMj0pNAeV2zeCJQAC8Ugp9yzJfPPoh6QbhgEH4ElU7cu5cb5BYQQxeMzFogBGFy7MQw4GBNZn99Nv42Yp1ShMMuicYpNEV+A== ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass smtp.mailfrom=amd.com; dmarc=pass action=none header.from=amd.com; dkim=pass header.d=amd.com; arc=none 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=QO6BLaAaP7fMmNILhR4aj55jiQQUXgUl3RZJH0mkINI=; b=wAFd0tYcdhcoYIuNeryahqkCaL/Kmx01Z6EEBt30btEQPBFUAAGHFjlNq/XclVruLA2iBjtI0mQlGYryE06AjpCcIE833GE8YQAS5nLmmKyla766l9VJKcJRFNjWUyX+o4ZnVb/7poQmrRvIAcpAohWPAv8BpqHLb3JZvn87JMc= Authentication-Results: dkim=none (message not signed) header.d=none;dmarc=none action=none header.from=amd.com; Received: from MW3PR12MB4553.namprd12.prod.outlook.com (2603:10b6:303:2c::19) by SN7PR12MB6689.namprd12.prod.outlook.com (2603:10b6:806:273::17) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.7875.20; Fri, 16 Aug 2024 20:38:57 +0000 Received: from MW3PR12MB4553.namprd12.prod.outlook.com ([fe80::b0ef:2936:fec1:3a87]) by MW3PR12MB4553.namprd12.prod.outlook.com ([fe80::b0ef:2936:fec1:3a87%6]) with mapi id 15.20.7875.018; Fri, 16 Aug 2024 20:38:57 +0000 Message-ID: <43051b97-38ac-4f4d-afdd-014387de4996@amd.com> Date: Fri, 16 Aug 2024 15:38:51 -0500 User-Agent: Mozilla Thunderbird From: "Moger, Babu" Subject: Re: [PATCH v6 07/22] x86/resctrl: Introduce the interface to display monitor mode Reply-To: babu.moger@amd.com To: James Morse Cc: x86@kernel.org, hpa@zytor.com, paulmck@kernel.org, rdunlap@infradead.org, tj@kernel.org, peterz@infradead.org, yanjiewtw@gmail.com, kim.phillips@amd.com, lukas.bulwahn@gmail.com, seanjc@google.com, jmattson@google.com, leitao@debian.org, jpoimboe@kernel.org, rick.p.edgecombe@intel.com, kirill.shutemov@linux.intel.com, jithu.joseph@intel.com, kai.huang@intel.com, kan.liang@linux.intel.com, daniel.sneddon@linux.intel.com, pbonzini@redhat.com, sandipan.das@amd.com, ilpo.jarvinen@linux.intel.com, peternewman@google.com, maciej.wieczor-retman@intel.com, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, eranian@google.com, dave.hansen@linux.intel.com, tglx@linutronix.de, bp@alien8.de, mingo@redhat.com, corbet@lwn.net, fenghua.yu@intel.com, reinette.chatre@intel.com References: Content-Language: en-US In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-ClientProxiedBy: SJ0PR13CA0006.namprd13.prod.outlook.com (2603:10b6:a03:2c0::11) To MW3PR12MB4553.namprd12.prod.outlook.com (2603:10b6:303:2c::19) Precedence: bulk X-Mailing-List: linux-doc@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: MW3PR12MB4553:EE_|SN7PR12MB6689:EE_ X-MS-Office365-Filtering-Correlation-Id: 0e9787be-3860-475b-4ce2-08dcbe3373c2 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|7416014|376014|1800799024|366016; X-Microsoft-Antispam-Message-Info: =?utf-8?B?RWtMSzEvVnp6M1pqcnZKVTRMQkg5dUp2NFUySzJWVXJ1K2VaNXRHcStvMnk0?= =?utf-8?B?dUZ4WHNwK0krME9aR3ZNZ2ZycURaQ2xuMyt5SnpYRU5qR2FQdXV5aVZZNG8w?= =?utf-8?B?aG91YklqeUJzN3RQNjZ2WmhHcWtxYVQ0RVFtaHdPVEo1NWNYVE9kbzZYNjQz?= =?utf-8?B?TFpWZGhKdGlVWUc0MkFqa0dsSHQ2ZVZvQ0RtOGRkMy9nSG1sS29Gb1VEZXgv?= =?utf-8?B?SVpZemR4WG5NTzk0YzVjN3lmTkdOcEVlMUhBcHk4bFdYTk1EK2JmUUJJSllX?= =?utf-8?B?a2hISkp3eU9PSUFza3VUTms2L3lxczdGSzQ3bEw5SW54SGVzUEtHTHBtMjZH?= =?utf-8?B?dVRuWHU4d2FBZ3MxcVBjNk85VkdVU2hkd29OcUR3OGptRW1CTnZ5QUlqVzlk?= =?utf-8?B?K1J6LzN2WjRUME9ELzR3NUM3Qm10TUdTOWlma0QwWlZudERJUmtkMVdkVFFF?= =?utf-8?B?UEVDMWZBSnA1bW9rakRzRlcvelVOOGUvQ29HOTd3Z1VDTmVBUG40VlRub2RN?= =?utf-8?B?TjZ0eDZZS2VUTThsUWlSK21DWkJYZThQYlRyUkdwZXp1bmhjNDd2SkdtRGVS?= =?utf-8?B?c2k1dHNsODVQMjUyKzdlZjh2RDhMeXJjZTlPS0lEK1VvTUJRVU02dzVIck1E?= =?utf-8?B?UzJXMmFyTkJxb2VqYWFuS1JGWCtIVGdRZWU2SjBpV0RJUS9zSU9xRUJlaU1s?= =?utf-8?B?T3l0L2xPNm0vc1Bob0hBS2ZxeWZFdkZHV1RmYjA5bkQ0bEFRR1dVSDkxVlA3?= =?utf-8?B?UzV1eGtBZGpqV09ZaFFaUXZQTG1DVEs0Yjc0dmcwMm9pN0VNWTlKS2p3M05v?= =?utf-8?B?Q2NCQ0M1MGxPMFlxWTBkaG9TNVFDbGJrOTZ6M1ZJekM4ck5GNEFQRy8vcXFV?= =?utf-8?B?ckt4M1U0c09vWGFuZFN2cDRoSWdXNzVPK3NxVDR0TmVYdjVpby9qYlZtUHVC?= =?utf-8?B?NlFsbkJhc1c3d3Y3VERZUVBFMjd4M0JsODRlUmkwZGRIOFVTczR0NzNyRU4x?= =?utf-8?B?MUFhbzF3ZXAvRHJKc28vSzVxVkYxT0dDQm9Ec2ZHdnZraWorYnhrcndHV1Ex?= =?utf-8?B?S09HS3VvN2J5ZzF6d0s2b21OWXcralphQmFVMUVORkRLdGtRaCtVSnhNaHI1?= =?utf-8?B?S1pQdzZ1enlWM1l1bVdFMVJzYklNSFVEOTlTejVJU1E0NjlYNXgwZ3YvcXVD?= =?utf-8?B?aGdla1p6NmJwelpsVHErd2RZVDNkZHN3WmhVUHB6am9XdUdkQnJQR2RzdXBm?= =?utf-8?B?Vk9scUpYTnZPL1RGaXVNeS92dXBmMmI4bzkyWnhLNS8vQVpiSEpnUytSbERj?= =?utf-8?B?SndLd25uamh0a0t1ZlpaUGJscDQ1TTJWSzJYbnlnVjZCNmdVbkZXOHZZSzQ0?= =?utf-8?B?czBndFhNVjlPNTh2c21jVlJjb3kxcHA3VThYaUo4RDNOWmNhdkVCL0UrTEJi?= =?utf-8?B?eHYwM2txV0lSUXF3OWt3TDFLRG93M0xXQ0Y2bnI4ck1TWEF4WnJOVXQxQlVm?= =?utf-8?B?cDY5VlBPNHNKazRGNHRDSHZ3c0hJajM0aE9NVWtmRDBvcDBhY0ExcTRVZS9v?= =?utf-8?B?MG5oc3dlK1JpRlIyVkJneVBIZjRIbEJSNDd3TWRGNWdNbUhoeFdLUGtNS2tj?= =?utf-8?B?ZXYveSt0cTF6dkt5YUJLeWpUVm5WTEFGTkMyNGJRcXc1RzJuSkI5bW9OZm9J?= =?utf-8?B?a3NxVzRyaVlUdEtOd1dZTExKOVc5ejNrVjhkcGw2aDI5NDFLYmprbFF4TStp?= =?utf-8?B?S3hibFpXNG1sNHNtZmdhbE5pYXcyd1F2NngwdnZpbnNtNkdNclNGZGtOd0ps?= =?utf-8?B?M0JmanFSdmMvK2srMm5uUT09?= X-Forefront-Antispam-Report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:MW3PR12MB4553.namprd12.prod.outlook.com;PTR:;CAT:NONE;SFS:(13230040)(7416014)(376014)(1800799024)(366016);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?utf-8?B?SHhackUxaTVCdjhjZHFqeW9ic1BVUGdDVk5JclFLVFVZNWpueFladUkramNM?= =?utf-8?B?aVQwUUlRUlVuUnpFdXhQOXptaE8vV2RORlBhNmZvaHExYzhlMEhHSnlNTGVu?= =?utf-8?B?bkdUSjcwUzFlOTQ0c1Q5MnFtK3N4a0tWY3JqbUlNeXcvNWRVL0FsT2JpaWNm?= =?utf-8?B?SG9MMTJnenFnT1p4TEtZYUIzM3AyK1pZaWxwNlJuMGZtV2lCMWlFaTFQVDNS?= =?utf-8?B?ZDd0QlNrRzJkRVBLTkMxQnVZaStwQmQ5NUYzWFhTREQxN0xqR3NYL3B2V0U3?= =?utf-8?B?czNoVlhyQm5pdVM0ZFA4ZUlEdmxpTXNId0VvWjRwSC9ZeTAvWkhCRzlBVndC?= =?utf-8?B?Z2cvT2dKTUdsYzFTa2prZ0wwQmhCUm5LdWFIQzZqcWxGc3A2UjlYYlQ0RGdz?= =?utf-8?B?UGhWcng5cTFBZEttdjVCNUY4cXNieVFIVzBvZ2w5enVZK3VnWjF5Tnh3TDJz?= =?utf-8?B?NUFWdkM4MWVOZEY4cFFUdGh2UmJTMEQ0SGRJUktFVk9mbGkwZjA5SmNjU2tM?= =?utf-8?B?WlFjaXNLK21XeGk4aXRMcldDNVFQbXBFWVZzdFEyK1NlcmxJT2ZEeVJhS3M4?= =?utf-8?B?Mml2OWZQTi9OaUIxMk1ZOHAyUTJyekc3c2dVTHUzRm5HdTZzM0FtbzRPa1pR?= =?utf-8?B?c3FuQTYrN3pKVUJ5c0dOTytjelkyVkVTSDhrU3ZHY1E1YnhZL1M3VElKYlNm?= =?utf-8?B?TFdSR1R1N2Fia0ZaYUJ1YkZqZkV4WkZibTM3eGNCVTRjQ2hsOWtvTnZCNDRt?= =?utf-8?B?N05tcXFQczBpalRldXVYK1R5OWxkVHYvZGNmZ24zUWZpL2ZFaldRb3dvemky?= =?utf-8?B?MUZvTUtKeWlaVW4rajU2ZUp5RVRwM3RSWStLSHpGOGgzc3JyTEVwbFEyNEtL?= =?utf-8?B?R3JDRTQ5WlFjRTJkL21NRm9RTjU3aFh1bE5xaG5KRmszbXM3ZkZyakFXUmJH?= =?utf-8?B?aE9DUHFkZjBMMU54dE1zbTRKWDd6RjhEcmQ1dS85OXNrVUpCVVJXWVYxNUVE?= =?utf-8?B?S1ZoNU0vbFhHU0xFVUE1YXZXT1hiZ0pIVEtocHhqT2NIV1phT3RoZFZOMUJs?= =?utf-8?B?MkhteGFwWHVjUjFBTjRiSlBNOVZ3YTVrV0FtYVhHUkZlL091VnFqOHE3TTdu?= =?utf-8?B?cUk1aGRyU3VZWEdhc3JjUWtQM3UrTWZZNGZ4WnJZUjh5Y0tTRFFnWTkzdWVI?= =?utf-8?B?ZDZsbE10ZHhQWVpJTktud1VUR040L21kK1U5OUpxeHFsTitBU0M1b3pkTGVC?= =?utf-8?B?Szl1M2FFOU4xRUkzbWdYdDltK2NBRkRPcWJtL3JGK2ljTjR0ZmRnMllxaGZy?= =?utf-8?B?Q1grR09NL1VUQ0tCUmh1UWU2QUFvMnRuNFBVbTFCdTFPWENtYlRzR2Z1T2Vj?= =?utf-8?B?ekdLVlRxM3F3WWMvZ2htbnpGaWdqdEdxZFgvYlFDK3ZPa2g4TnRJdytzbENo?= =?utf-8?B?L1gxallNL0pqVkRNeTFla1lYcWFhR2lSakkvSEZEYWZORXJmZ1hBSHgvMk1j?= =?utf-8?B?aml6RWIvYVVCUjkzTnpFYmFqM0VwaC9xNTBDdHRhbUNIaUJXb0VNNUtsUzFk?= =?utf-8?B?cnNuSTRIaS9PTzJGNWV3MGpROGhvNlE1QU1QaG9hcm5HeHFDNnVibXloTW5I?= =?utf-8?B?RmNPRmMrbEl2bXFiMVJEaXFKTFZGQkVtRDRtK0RXMFZFU1JXTHd5MVdzVlE3?= =?utf-8?B?WEVDVVgvSXVDWEd3R29hT2lFRzkzbmdsekcvQnpjNFcrTFEvTmczejZ3VmEy?= =?utf-8?B?RFlqTm9hd2N1U0hFV0tRUjdKaS9NeGhxcmZLQTl4SXdFT1JBMmI1WnE1V3BJ?= =?utf-8?B?ajU2K25iY2hLenBnWHdXU1pLUEpibzNFVGt3L0FOMWVjQWI2MW1HZk9WL2Qw?= =?utf-8?B?NUgybVdMa1Ercnl0SWZUc0VBNElmSng2SkNCc3ZRUk8ramJJWERRSXNaTUFL?= =?utf-8?B?VlpOWDlPNEVVYzRYV3RnajhwVEhkOEYvY2kzTU5KVmtuT3hadW5UT3EySDlp?= =?utf-8?B?Sk5YK1BtRWZ1eEdyZ3k1ZVd5ekhzN1lzcW5FUjk4Y1FOa2RDSmRqVnZvZEh0?= =?utf-8?B?OVRsd1RoS1FjWlhOanlQNzkxM1FXa1dyeHF5UWdZWk5xMEwwVHdFYUNlVXVt?= =?utf-8?Q?XMD0=3D?= X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-Network-Message-Id: 0e9787be-3860-475b-4ce2-08dcbe3373c2 X-MS-Exchange-CrossTenant-AuthSource: MW3PR12MB4553.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 16 Aug 2024 20:38:57.5595 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 3dd8961f-e488-4e60-8e11-a82d994e183d X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: rKKZaULrzVGUT7ZkL4kIBzj2fl0NJfbvrgTth8KaazrahQ1RapyDsdbpRWztiZ48 X-MS-Exchange-Transport-CrossTenantHeadersStamped: SN7PR12MB6689 Hi James, On 8/16/24 11:56, James Morse wrote: > Hi Babu, > > On 06/08/2024 23:00, Babu Moger wrote: >> The mbm_mode displays list of monitor modes supported. >> >> The mbm_cntr_assign is one of the currently supported modes. It is also >> called ABMC (Assignable Bandwidth Monitoring Counters) feature. ABMC >> feature provides option to assign a hardware counter to an RMID and >> monitor the bandwidth as long as it is assigned. ABMC mode is enabled >> by default when supported. >> >> Legacy mode works without the assignment option. >> >> Provide an interface to display the monitor mode on the system. >> $cat /sys/fs/resctrl/info/L3_MON/mbm_mode >> [mbm_cntr_assign] >> legacy >> >> Switching the mbm_mode will reset all the mbm counters of all resctrl >> groups. > >> diff --git a/Documentation/arch/x86/resctrl.rst b/Documentation/arch/x86/resctrl.rst >> index 30586728a4cd..d4ec605b200a 100644 >> --- a/Documentation/arch/x86/resctrl.rst >> +++ b/Documentation/arch/x86/resctrl.rst >> @@ -257,6 +257,40 @@ with the following files: >> # cat /sys/fs/resctrl/info/L3_MON/mbm_local_bytes_config >> 0=0x30;1=0x30;3=0x15;4=0x15 >> >> +"mbm_mode": >> + Reports the list of assignable monitoring features supported. The >> + enclosed brackets indicate which feature is enabled. >> + :: >> + >> + cat /sys/fs/resctrl/info/L3_MON/mbm_mode >> + [mbm_cntr_assign] >> + legacy >> + >> + "mbm_cntr_assign": >> + AMD's ABMC feature is one of the mbm_cntr_assign mode supported. >> + The bandwidth monitoring feature on AMD system only guarantees >> + that RMIDs currently assigned to a processor will be tracked by >> + hardware. The counters of any other RMIDs which are no longer >> + being tracked will be reset to zero. The MBM event counters >> + return "Unavailable" for the RMIDs that are not tracked by >> + hardware. So, there can be only limited number of groups that can >> + give guaranteed monitoring numbers. With ever changing configurations >> + there is no way to definitely know which of these groups are being >> + tracked for certain point of time. Users do not have the option to >> + monitor a group or set of groups for certain period of time without >> + worrying about RMID being reset in between. >> + >> + The ABMC feature provides an option to the user to assign a hardware >> + counter to an RMID and monitor the bandwidth as long as it is assigned. >> + The assigned RMID will be tracked by the hardware until the user >> + unassigns it manually. There is no need to worry about counters being >> + reset during this period. > > While debugging my rebase of MPAM on top of this series, I've come back to this wording a > few times to try and work out what I should expect to see ... > > Is it possible to disentangle the AMD hardware feature description from the description of > the filesystem behaviour this enables? You are really describing what the hardware does if > you don't enable this mode... > > An incomplete suggestion of the shape would be something like: > > | In mbm_cntr_assign mode user-space is able to specify which control > | or monitor groups in resctrl should have a hardware counter assigned > | using the 'mbm_control' file. The number of hardware counters available > | is described in the 'num_mbm_cntrs' file. > | Changing this mode will cause all counters on a resource to reset. > | > | The feature is needed on platforms which support more control and monitor > | groups than hardware counters, meaning 'unassigned' control or monitor groups will > | report 'Unavailable' or not count all the traffic in an unpredictable way. > | > | Platforms with AMDs ABMC feature enable this mode by default so that counters > | remain assigned even when the corresponding RMID is not in use by any processor. > Looks good to me. > >> + "Legacy": > > Calling "enough hardware counters" 'legacy' is a bit curious.... 'default'? "Default" Sound good me to if no objections from others. > (but I haven't worked out the benefit of disabling this mode, so maybe it doesn't need a > name.) > >> + Legacy mode works without the assignment option. The monitoring works >> + as long as there are enough RMID counters available to support number >> + of monitoring groups. > > How can user-space tell this is the case? Could we be specific as to what 'works' means? > > Something like: > | By default resctrl assumes each control and monitor group has a hardware counter. > | Hardware without this property will still allow more control or monitor groups > | than 'num_mbm_cntrs' to be created. Reading the mbm files may report > | 'Unavailable' if there is no hardware resource assigned. Looks good. > > > N.B. I don't suggest referring to the num_rmid file in these as MPAM doesn't have an > equivalent property. > > > Thanks, > > James > -- Thanks Babu Moger