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Wysocki" , Huang Rui CC: , , , , Shuah Khan , , "Nathan Fontenot" , Deepak Sharma , Alex Deucher , Mario Limonciello , Shimmer Huang , "Perry Yuan" , Xiaojian Du , Viresh Kumar , Borislav Petkov , Meng Li Subject: [PATCH V5 6/7] Documentation: amd-pstate: introduce amd-pstate preferred core Date: Tue, 5 Sep 2023 09:51:15 +0800 Message-ID: <20230905015116.2268926-7-li.meng@amd.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20230905015116.2268926-1-li.meng@amd.com> References: <20230905015116.2268926-1-li.meng@amd.com> MIME-Version: 1.0 X-Originating-IP: [10.180.168.240] 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: CY4PEPF0000EDD0:EE_|PH7PR12MB6737:EE_ X-MS-Office365-Filtering-Correlation-Id: 82820a86-8221-4716-50e1-08dbadb2bb2e X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0; X-Microsoft-Antispam-Message-Info: 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 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:(13230031)(4636009)(136003)(39860400002)(346002)(396003)(376002)(1800799009)(186009)(82310400011)(451199024)(40470700004)(46966006)(36840700001)(478600001)(110136005)(26005)(2616005)(70206006)(70586007)(16526019)(1076003)(426003)(54906003)(336012)(7696005)(316002)(2906002)(8676002)(4326008)(6636002)(8936002)(5660300002)(86362001)(356005)(36756003)(81166007)(82740400003)(47076005)(41300700001)(40460700003)(83380400001)(36860700001)(40480700001)(36900700001); DIR:OUT; SFP:1101; X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 05 Sep 2023 01:52:15.8122 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 82820a86-8221-4716-50e1-08dbadb2bb2e 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: CY4PEPF0000EDD0.namprd03.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: PH7PR12MB6737 Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org Introduce amd-pstate preferred core. check hardware preferred core state: $ cat /sys/devices/system/cpu/amd-pstate/hw_prefcore check preferred core state: $ cat /sys/devices/system/cpu/amd-pstate/prefcore Signed-off-by: Meng Li --- Documentation/admin-guide/pm/amd-pstate.rst | 68 ++++++++++++++++++++- 1 file changed, 67 insertions(+), 1 deletion(-) diff --git a/Documentation/admin-guide/pm/amd-pstate.rst b/Documentation/admin-guide/pm/amd-pstate.rst index 1cf40f69278c..204f5d49d47d 100644 --- a/Documentation/admin-guide/pm/amd-pstate.rst +++ b/Documentation/admin-guide/pm/amd-pstate.rst @@ -300,7 +300,7 @@ platforms. The AMD P-States mechanism is the more performance and energy efficiency frequency management method on AMD processors. -AMD Pstate Driver Operation Modes +``amd-pstate`` Driver Operation Modes ================================= ``amd_pstate`` CPPC has 3 operation modes: autonomous (active) mode, @@ -353,6 +353,48 @@ is activated. In this mode, driver requests minimum and maximum performance level and the platform autonomously selects a performance level in this range and appropriate to the current workload. +``amd-pstate`` Preferred Core +================================= + +The core frequency is subjected to the process variation in semiconductors. +Not all cores are able to reach the maximum frequency respecting the +infrastructure limits. Consequently, AMD has redefined the concept of +maximum frequency of a part. This means that a fraction of cores can reach +maximum frequency. To find the best process scheduling policy for a given +scenario, OS needs to know the core ordering informed by the platform through +highest performance capability register of the CPPC interface. + +``amd-pstate`` preferred core enables the scheduler to prefer scheduling on +cores that can achieve a higher frequency with lower voltage. The preferred +core rankings can dynamically change based on the workload, platform conditions, +thermals and ageing. + +The priority metric will be initialized by the ``amd-pstate`` driver. The ``amd-pstate`` +driver will also determine whether or not ``amd-pstate`` preferred core is +supported by the platform. + +``amd-pstate`` driver will provide an initial core ordering when the system boots. +The platform uses the CPPC interfaces to communicate the core ranking to the +operating system and scheduler to make sure that OS is choosing the cores +with highest performance firstly for scheduling the process. When ``amd-pstate`` +driver receives a message with the highest performance change, it will +update the core ranking and set the cpu's priority. + +``amd-pstate`` Preferred Core Switch +================================= +Kernel Parameters +----------------- + +``amd-pstate`` peferred core`` has two states: enable and disable. +Enable/disable states can be chosen by different kernel parameters. +Default enable ``amd-pstate`` preferred core. + +``amd_prefcore=disable`` + +for systems that support ``amd-pstate`` preferred core, the core rankings will +always be advertised by the platform. But OS can choose to ignore that via the +kernel parameter ``amd_prefcore=disable``. + User Space Interface in ``sysfs`` - General =========================================== @@ -385,6 +427,30 @@ control its functionality at the system level. They are located in the to the operation mode represented by that string - or to be unregistered in the "disable" case. +``hw_prefcore`` + Preferred core state of hardware: "supported" or "unsupported". + + "supported" + The processor and power firmware support preferred core. + + "unsupported" + The processor and power firmware don't support preferred core. + + + This attribute is read-only to check the state of hardware preferred core. + +``prefcore`` + Preferred core state of the driver: "enabled" or "disabled". + + "enabled" + Enable the ``amd-pstate`` preferred core. + + "disabled" + Disable the ``amd-pstate`` preferred core + + + This attribute is read-only to check the state of preferred core. + ``cpupower`` tool support for ``amd-pstate`` ===============================================