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Shenoy" To: Mario Limonciello Cc: Perry Yuan , Dhananjay Ugwekar , "open list:X86 ARCHITECTURE (32-BIT AND 64-BIT)" , "open list:CPU FREQUENCY SCALING FRAMEWORK" , Mario Limonciello Subject: Re: [PATCH v2 04/17] cpufreq/amd-pstate: Overhaul locking Message-ID: References: <20250215005244.1212285-1-superm1@kernel.org> <20250215005244.1212285-5-superm1@kernel.org> Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250215005244.1212285-5-superm1@kernel.org> X-ClientProxiedBy: PN2PR01CA0125.INDPRD01.PROD.OUTLOOK.COM (2603:1096:c01:6::10) To DS7PR12MB8252.namprd12.prod.outlook.com (2603:10b6:8:ee::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: DS7PR12MB8252:EE_|MN2PR12MB4456:EE_ X-MS-Office365-Filtering-Correlation-Id: 56a2e3dc-ce23-4b2a-f078-08dd4f33286c X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|1800799024|376014|366016; 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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?aJljnIjjXWViiLNkV9CFWmKXekaLxS2yg00mK6hsSHDQUF3UMOq6qKg5MX+5?= =?us-ascii?Q?Q630BSOD8kUmhTY4CrlI/E5O+BoIzozdOvk13SZJBHsS/9A/8qToBQoXrxQU?= =?us-ascii?Q?1u/kQpabN0VbnUIjIOATxXXZ1ua881Xxu8h5XICsxpR1FGHd1n6y+BNjrNt6?= =?us-ascii?Q?h2zFyBM5wX4kELq3JVzGIGm1DweAaR0nCNtGM8zs/iHD6AZjQTTESMCfkuoe?= =?us-ascii?Q?8rvomGu5UMiyG71v/pr1yeujAsN4rx1IuymHqPfwThs0Sb8J4lHAt82HGom+?= =?us-ascii?Q?b4F2N2ENur33GmOxeI6nEZsscf9AhVQZaW+uJV/YDjhkPLuqrZkK6A+4SKfF?= =?us-ascii?Q?5YqgitJ0oPMFSgUqqGnWW4xuYg2u1sdshDGQrJv9ePVm0rFkjkrU5c3h3Xwu?= =?us-ascii?Q?kA/z3rYV1VeeFZI0oM5zOKiIgXgP8JLBwhqHV+VckYiZUfvHGp5FhcYoCjiY?= =?us-ascii?Q?TAvZmTa4ZWFKw6NL0XbyydrvU33LiU5Fj8Luv5DRSRbOg9iqWmpse0Y+0o4b?= =?us-ascii?Q?UiJQONpFeIG5zuHZfRvTbekZCk+GacKg1+HY3b4rjTybl8ZkuNv1SRMAOXcx?= =?us-ascii?Q?484AtfOPMJB7xBiqDSciRMBGHcowxDikC/oX6acwvEZEdnQI1bfQcPBQgrEj?= =?us-ascii?Q?sk0luwXzDmPyfrp08RUyFRka62IFilR+o06KeXrdumgPaqkhqv4OOV+Agftz?= =?us-ascii?Q?0oEN0/ZkTk8zvjE61u87l3d1gw56AI70E7g32EAF6hxaFHJx0x9i/wg9MO/+?= =?us-ascii?Q?xzSQyY5q5/w5IycKX3X8sDOjg8dqa7NilerkCt8i3rjqauVXxktGQBUkFfJo?= =?us-ascii?Q?OeV4vpFi9PctaA0xtIsGKyhL4rmWhuXQ/Cnp5xDxWQXnETEbUIwFdafhm2Bq?= =?us-ascii?Q?ZdRr7jzYCshRJCc/+cTnVBGLuWPDoq2wUchmqwnNdvXutTDjVLizQaQD1+cY?= =?us-ascii?Q?eDVito2T2onhKMYRGQMwfbwAMdTXRC4QYtQv5HBkD1XgXf0qu2GOP9IFgzAM?= =?us-ascii?Q?Zbyx/eonBfSpOS4F41DkZtlDJ21f9Hv6tPQR40BrCh3WPfbCsU1ECQNM2y92?= =?us-ascii?Q?LD+U4g3fVD0UHJBYhc77o6myNrJQvmNfVkSw3m0aA580qAePcPXW4DB4lJnp?= =?us-ascii?Q?b5JB5RbqjlEgWRTapaSwtnBdrtkZo9GBZI3UQa1nvJAfhXsvc8Iny5jJA6K9?= =?us-ascii?Q?tjP0OlP6MMVW2H3CqzScmFkwRGAC8gcSWR1tNTd7AHQzruzJwiBSlhtGI3Eb?= =?us-ascii?Q?Kn57IGo7fL3ksak5zFKPYOyp16icwlsGFzzrdknrQRxM8goUWRKkMSpXey7l?= =?us-ascii?Q?Ozujzv6PlYpMjN3kGHd5UEG1p1QAIJEu+ywG4HU8YLyoGZmTsHHp7MHLwsv+?= =?us-ascii?Q?WbXQMD4tcmum7rbq5Radsx0erLh7+D8G1GbKOGsSOwICBvSRk3WIZRjZOadU?= =?us-ascii?Q?1hX4TD3+3TSJBfK3iS64FtVIiw/VcDFmDPi9q/7mdXW6yws1ZVbFSzDmszUg?= =?us-ascii?Q?HqOBBGTC6Bx2mvtu3WGOBI5cyjWZ1IAVvk772548+MrJuF4STww0idWDxTIl?= =?us-ascii?Q?geynSF/lfX9xQ420ik7CVuBxO3Hphuy8at6wbQXZ?= X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-Network-Message-Id: 56a2e3dc-ce23-4b2a-f078-08dd4f33286c X-MS-Exchange-CrossTenant-AuthSource: DS7PR12MB8252.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 17 Feb 2025 09:12:10.1054 (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: gjK81A2ybucmbDggV2eb0hUFqtU6xEd8TzQlptzFLVkjUwseOyJATE0P5+xw1JoPT0VIUlq9+liiuTmLflZJ4A== X-MS-Exchange-Transport-CrossTenantHeadersStamped: MN2PR12MB4456 On Fri, Feb 14, 2025 at 06:52:31PM -0600, Mario Limonciello wrote: > From: Mario Limonciello > > amd_pstate_cpu_boost_update() and refresh_frequency_limits() both > update the policy state and have nothing to do with the amd-pstate > driver itself. > > A global "limits" lock doesn't make sense because each CPU can have > policies changed independently. Each time a CPU changes values they > will atomically be written to the per-CPU perf member. Drop per CPU > locking cases. > > The remaining "global" driver lock is used to ensure that only one > entity can change driver modes at a given time. Yup. The patch looks good to me. Reviewed-by: Gautham R. Shenoy -- Thanks and Regards gautham. > > Signed-off-by: Mario Limonciello > --- > drivers/cpufreq/amd-pstate.c | 13 +++---------- > 1 file changed, 3 insertions(+), 10 deletions(-) > > diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c > index 8c3b54030ec56..044091806f14f 100644 > --- a/drivers/cpufreq/amd-pstate.c > +++ b/drivers/cpufreq/amd-pstate.c > @@ -196,7 +196,6 @@ static inline int get_mode_idx_from_str(const char *str, size_t size) > return -EINVAL; > } > > -static DEFINE_MUTEX(amd_pstate_limits_lock); > static DEFINE_MUTEX(amd_pstate_driver_lock); > > static u8 msr_get_epp(struct amd_cpudata *cpudata) > @@ -752,7 +751,6 @@ static int amd_pstate_set_boost(struct cpufreq_policy *policy, int state) > pr_err("Boost mode is not supported by this processor or SBIOS\n"); > return -EOPNOTSUPP; > } > - guard(mutex)(&amd_pstate_driver_lock); > > ret = amd_pstate_cpu_boost_update(policy, state); > refresh_frequency_limits(policy); > @@ -1172,8 +1170,6 @@ static ssize_t store_energy_performance_preference( > if (ret < 0) > return -EINVAL; > > - guard(mutex)(&amd_pstate_limits_lock); > - > ret = amd_pstate_set_energy_pref_index(policy, ret); > > return ret ? ret : count; > @@ -1346,8 +1342,10 @@ int amd_pstate_update_status(const char *buf, size_t size) > if (mode_idx < 0 || mode_idx >= AMD_PSTATE_MAX) > return -EINVAL; > > - if (mode_state_machine[cppc_state][mode_idx]) > + if (mode_state_machine[cppc_state][mode_idx]) { > + guard(mutex)(&amd_pstate_driver_lock); > return mode_state_machine[cppc_state][mode_idx](mode_idx); > + } > > return 0; > } > @@ -1368,7 +1366,6 @@ static ssize_t status_store(struct device *a, struct device_attribute *b, > char *p = memchr(buf, '\n', count); > int ret; > > - guard(mutex)(&amd_pstate_driver_lock); > ret = amd_pstate_update_status(buf, p ? p - buf : count); > > return ret < 0 ? ret : count; > @@ -1640,8 +1637,6 @@ static int amd_pstate_epp_cpu_offline(struct cpufreq_policy *policy) > if (cpudata->suspended) > return 0; > > - guard(mutex)(&amd_pstate_limits_lock); > - > if (trace_amd_pstate_epp_perf_enabled()) { > trace_amd_pstate_epp_perf(cpudata->cpu, perf.highest_perf, > AMD_CPPC_EPP_BALANCE_POWERSAVE, > @@ -1678,8 +1673,6 @@ static int amd_pstate_epp_resume(struct cpufreq_policy *policy) > struct amd_cpudata *cpudata = policy->driver_data; > > if (cpudata->suspended) { > - guard(mutex)(&amd_pstate_limits_lock); > - > /* enable amd pstate from suspend state*/ > amd_pstate_epp_reenable(policy); > > -- > 2.43.0 >