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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 , "Oleksandr Natalenko" , Meng Li , Wyes Karny Subject: [PATCH V9 6/7] Documentation: amd-pstate: introduce amd-pstate preferred core Date: Fri, 13 Oct 2023 10:57:40 +0800 Message-ID: <20231013025741.3332520-7-li.meng@amd.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20231013025741.3332520-1-li.meng@amd.com> References: <20231013025741.3332520-1-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: CO1PEPF000044F3:EE_|SA3PR12MB9200:EE_ X-MS-Office365-Filtering-Correlation-Id: bd6e18d7-1a6a-4a95-1cfe-08dbcb9848cb X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0; X-Microsoft-Antispam-Message-Info: xR/H6tdRKlYC+o8RIteZu8eyT6eWOC/HMcD4lQu868QLeJu9TqjNO5+UYHMlKtI4M2jWNxNtt79nIIsaGTT/6d0fRrxqPE4P1F/5oebDWLyaVeGu9ohP4OuRnVcm8xIgFsIPZqbACefC4Ba9uVmwngpsjXexxLkjTJEf+bKVeDy/yJNEGP3PX73PpZt6FbBjoHV38CDqykSdUeSujN7szzRCqSj9CUXlGlyFoOtHkfDo1+SEbNWgDJfRwKCWtaulL3hwsWrHX6GQ7aWRkeg+cOc+eF7A7itGC9pAWLfUuHN+NT3rITACr/gOfzCQZlQW2yLU6x7H65PUz36lNtXB6EUF1K/NZVQhfhfxT46Y3Rp+Ztj4EcVd8XX8KbnIfRmKVJqNiKfP+lOVC8A7ecoWOOmjCFtIOVEDRp8iERiypy5WfACrfk7DQSLFx29IZIsH8TGSTHvGWhI6ztIOtIQf5lEeaDGmoJU/NJT5QOEDxj/7naN1+z0bs3QK2FHwtJnpGZ0fVd3M0UIeDNVFbo7+TqpHiFGdiIkQMzut1SWR9KkZR+SdFA5qZPOFpQ8+41wbNxpxKSt0eID94kBmzFRjQEtAklEHt8bz4TyfHLKGbSUq2iAUVm/Q9lI0PfBwI7vCThc9/WUm3ZMZDbgif5EtcwmiagrC6QUpN614vi/1vCqeofUZoJhpEl8NebGFHrCdA1Nj1/1j+8RExPnXkE7GcIa6boFzIjt36CS7VpITuTEPwb4j+hUPLsXa30L5FAuoBylduCU7TsRSAeQr3NcufA== 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)(346002)(39860400002)(396003)(376002)(136003)(230922051799003)(82310400011)(186009)(451199024)(1800799009)(64100799003)(36840700001)(40470700004)(46966006)(4326008)(8936002)(8676002)(54906003)(70586007)(6666004)(70206006)(6636002)(316002)(7696005)(5660300002)(26005)(2616005)(478600001)(16526019)(336012)(426003)(1076003)(41300700001)(110136005)(40460700003)(47076005)(83380400001)(36860700001)(40480700001)(82740400003)(81166007)(2906002)(356005)(7416002)(36756003)(86362001)(36900700001); DIR:OUT; SFP:1101; X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 13 Oct 2023 02:58:31.8076 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: bd6e18d7-1a6a-4a95-1cfe-08dbcb9848cb 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: CO1PEPF000044F3.namprd05.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: SA3PR12MB9200 Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org Introduce amd-pstate preferred core. check preferred core state set by the kernel parameter: $ cat /sys/devices/system/cpu/amd-pstate/prefcore Tested-by: Oleksandr Natalenko Reviewed-by: Wyes Karny Reviewed-by: Mario Limonciello Reviewed-by: Huang Rui Signed-off-by: Meng Li --- Documentation/admin-guide/pm/amd-pstate.rst | 59 ++++++++++++++++++++- 1 file changed, 57 insertions(+), 2 deletions(-) diff --git a/Documentation/admin-guide/pm/amd-pstate.rst b/Documentation/admin-guide/pm/amd-pstate.rst index 1cf40f69278c..0b832ff529db 100644 --- a/Documentation/admin-guide/pm/amd-pstate.rst +++ b/Documentation/admin-guide/pm/amd-pstate.rst @@ -300,8 +300,8 @@ 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, non-autonomous (passive) mode and guided autonomous (guided) 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 +427,19 @@ 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. +``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 set + by the kernel parameter. + ``cpupower`` tool support for ``amd-pstate`` ===============================================