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Subject: Re: [PATCH 3/5] cpufreq: qcom-cpufreq-hw: Update offline CPUs per-cpu
 thermal pressure
To:     Thara Gopinath <thara.gopinath@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,
        bjorn.andersson@linaro.org, agross@kernel.org
References: <20211007080729.8262-1-lukasz.luba@arm.com>
 <20211007080729.8262-4-lukasz.luba@arm.com>
 <be6fb99f-90bc-9ba1-b5a7-034b30734158@linaro.org>
From:   Lukasz Luba <lukasz.luba@arm.com>
Message-ID: <7ef0ce1c-40c7-ad08-c7e8-5b1a8507508c@arm.com>
Date:   Fri, 15 Oct 2021 13:13:47 +0100
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On 10/11/21 10:17 PM, Thara Gopinath wrote:
> 
> 
> On 10/7/21 4:07 AM, Lukasz Luba wrote:
>> The thermal pressure signal gives information to the scheduler about
>> reduced CPU capacity due to thermal. It is based on a value stored in
>> a per-cpu 'thermal_pressure' variable. The online CPUs will get the
>> new value there, while the offline won't. Unfortunately, when the CPU
>> is back online, the value read from per-cpu variable might be wrong
>> (stale data).  This might affect the scheduler decisions, since it
>> sees the CPU capacity differently than what is actually available.
>>
>> Fix it by making sure that all online+offline CPUs would get the
>> proper value in their per-cpu variable when there is throttling
>> or throttling is removed.
>>
>> Fixes: 275157b367f479 ("cpufreq: qcom-cpufreq-hw: Add dcvs interrupt 
>> support")
>> Signed-off-by: Lukasz Luba <lukasz.luba@arm.com>
> 
> Thanks for the fix.
> 
> Reviewed-by: Thara Gopinath <thara.gopinath@linaro.org>
> 

Thank you for the review!