From: Lukasz Luba <lukasz.luba@arm.com>
To: Bjorn Andersson <bjorn.andersson@linaro.org>
Cc: linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org,
linux-arm-kernel@lists.infradead.org,
linux-arm-msm@vger.kernel.org, sudeep.holla@arm.com,
will@kernel.org, catalin.marinas@arm.com, linux@armlinux.org.uk,
gregkh@linuxfoundation.org, rafael@kernel.org,
viresh.kumar@linaro.org, amitk@kernel.org,
daniel.lezcano@linaro.org, amit.kachhap@gmail.com,
thara.gopinath@linaro.org, agross@kernel.org
Subject: Re: [PATCH v2 1/5] arch_topology: Introduce thermal pressure update function
Date: Thu, 28 Oct 2021 08:16:28 +0100 [thread overview]
Message-ID: <a75b08d9-cf0f-b132-b07e-878b10d133a2@arm.com> (raw)
In-Reply-To: <YXmdyeOmNS2x3K0W@ripper>
On 10/27/21 7:43 PM, Bjorn Andersson wrote:
> On Fri 15 Oct 07:45 PDT 2021, Lukasz Luba wrote:
>> diff --git a/arch/arm64/include/asm/topology.h b/arch/arm64/include/asm/topology.h
> [..]
>> +/**
>> + * topology_thermal_pressure_update() - Update thermal pressure for CPUs
>> + * @cpus : The related CPUs for which capacity has been reduced
>> + * @capped_freq : The maximum allowed frequency that CPUs can run at
>
> I know this matches what I see in e.g. the Qualcomm cpufreq hw driver,
> but in what cases will @capped_freq differ from
> cpufreq_get_hw_max_freq(cpumask_first(cpus))?
The @capped_freq is the maximum allowed frequency value due to
thermal reasons, which will always be lower or equal to the value
returned by cpufreq_get_hw_max_freq()
(effectively: 'policy->cpuinfo.max_freq').
We limit the frequency (and voltage) of CPU to reduce power (and heat)
in the passive cooling system. That information is important to us,
because scheduler needs to know how fast the CPU can go. It cannot
assume that the speed is always 'policy->cpuinfo.max_freq'. Often
it's less then that at heavy load or GPU heavy load (the same SoC).
Regards,
Lukasz
next prev parent reply other threads:[~2021-10-28 7:16 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-10-15 14:45 [PATCH v2 0/5] Refactor thermal pressure update to avoid code duplication Lukasz Luba
2021-10-15 14:45 ` [PATCH v2 1/5] arch_topology: Introduce thermal pressure update function Lukasz Luba
2021-10-26 16:51 ` Dietmar Eggemann
2021-10-27 8:56 ` Lukasz Luba
2021-10-27 13:35 ` Dietmar Eggemann
2021-10-27 18:43 ` Bjorn Andersson
2021-10-28 7:16 ` Lukasz Luba [this message]
2021-10-28 23:12 ` Bjorn Andersson
2021-10-28 5:44 ` Viresh Kumar
2021-10-28 7:19 ` Lukasz Luba
2021-10-15 14:45 ` [PATCH v2 2/5] thermal: cpufreq_cooling: Use new " Lukasz Luba
2021-10-26 16:51 ` Dietmar Eggemann
2021-10-27 9:00 ` Lukasz Luba
2021-10-15 14:45 ` [PATCH v2 3/5] cpufreq: qcom-cpufreq-hw: Update offline CPUs per-cpu thermal pressure Lukasz Luba
2021-10-15 14:45 ` [PATCH v2 4/5] cpufreq: qcom-cpufreq-hw: Use new thermal pressure update function Lukasz Luba
2021-10-15 14:45 ` [PATCH v2 5/5] arch_topology: Remove unused topology_set_thermal_pressure() and related Lukasz Luba
2021-10-25 16:43 ` [PATCH v2 0/5] Refactor thermal pressure update to avoid code duplication Lukasz Luba
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