From: Sudeep Holla <sudeep.holla@arm.com>
To: Ionela Voinescu <ionela.voinescu@arm.com>
Cc: "Rafael J . Wysocki" <rjw@rjwysocki.net>,
Sudeep Holla <sudeep.holla@arm.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>,
Giovanni Gherdovich <ggherdovich@suse.cz>,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>,
Valentin Schneider <valentin.schneider@arm.com>,
Dietmar Eggemann <dietmar.eggemann@arm.com>,
Sean Kelley <skelley@nvidia.com>,
Pierre Gondois <pierre.gondois@arm.com>,
linux-kernel@vger.kernel.org, linux-acpi@vger.kernel.org,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v3 2/3] arch_topology: obtain cpu capacity using information from CPPC
Date: Wed, 9 Mar 2022 09:54:24 +0000 [thread overview]
Message-ID: <Yih5UCRKdYvlD4Bx@bogus> (raw)
In-Reply-To: <20220302180913.13229-3-ionela.voinescu@arm.com>
On Wed, Mar 02, 2022 at 06:09:12PM +0000, Ionela Voinescu wrote:
> Define topology_init_cpu_capacity_cppc() to use highest performance
> values from _CPC objects to obtain and set maximum capacity information
> for each CPU. acpi_cppc_processor_probe() is a good point at which to
> trigger the initialization of CPU (u-arch) capacity values, as at this
> point the highest performance values can be obtained from each CPU's
> _CPC objects. Architectures can therefore use this functionality
> through arch_init_invariance_cppc().
>
> The performance scale used by CPPC is a unified scale for all CPUs in
> the system. Therefore, by obtaining the raw highest performance values
> from the _CPC objects, and normalizing them on the [0, 1024] capacity
> scale, used by the task scheduler, we obtain the CPU capacity of each
> CPU.
>
> While an ACPI Notify(0x85) could alert about a change in the highest
> performance value, which should in turn retrigger the CPU capacity
> computations, this notification is not currently handled by the ACPI
> processor driver. When supported, a call to arch_init_invariance_cppc()
> would perform the update.
>
> Signed-off-by: Ionela Voinescu <ionela.voinescu@arm.com>
> Tested-by: Valentin Schneider <valentin.schneider@arm.com>
> Cc: Sudeep Holla <sudeep.holla@arm.com>
Looks good to me. FWIW,
Acked-by: Sudeep Holla <sudeep.holla@arm.com>
--
Regards,
Sudeep
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next prev parent reply other threads:[~2022-03-09 9:55 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-03-02 18:09 [PATCH v3 0/3] arch_topology, ACPI: populate cpu capacity from CPPC Ionela Voinescu
2022-03-02 18:09 ` [PATCH v3 1/3] x86, ACPI: rename init_freq_invariance_cppc to arch_init_invariance_cppc Ionela Voinescu
2022-03-08 18:05 ` Rafael J. Wysocki
2022-03-08 18:22 ` Rafael J. Wysocki
2022-03-09 9:30 ` Ionela Voinescu
2022-03-02 18:09 ` [PATCH v3 2/3] arch_topology: obtain cpu capacity using information from CPPC Ionela Voinescu
2022-03-09 9:54 ` Sudeep Holla [this message]
2022-03-09 10:21 ` Yicong Yang
2022-03-09 15:37 ` Ionela Voinescu
2022-03-10 6:39 ` Yicong Yang
2022-03-10 15:08 ` Ionela Voinescu
2022-03-11 8:42 ` Yicong Yang
2022-03-02 18:09 ` [PATCH v3 3/3] arm64, topology: enable use of init_cpu_capacity_cppc() Ionela Voinescu
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