Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Subject: Re: [PATCH 3/5] cpufreq: qcom-cpufreq-hw: Update offline CPUs per-cpu
 thermal pressure
To:     Lukasz Luba <lukasz.luba@arm.com>, linux-kernel@vger.kernel.org,
        linux-pm@vger.kernel.org
Cc:     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>
From:   Thara Gopinath <thara.gopinath@linaro.org>
Message-ID: <be6fb99f-90bc-9ba1-b5a7-034b30734158@linaro.org>
Date:   Mon, 11 Oct 2021 17:17:08 -0400
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101
 Thunderbird/78.11.0
MIME-Version: 1.0
In-Reply-To: <20211007080729.8262-4-lukasz.luba@arm.com>
Content-Type: text/plain; charset=utf-8; format=flowed
Content-Language: en-US
Content-Transfer-Encoding: 7bit
Precedence: bulk


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>

> ---
>   drivers/cpufreq/qcom-cpufreq-hw.c | 3 ++-
>   1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/cpufreq/qcom-cpufreq-hw.c b/drivers/cpufreq/qcom-cpufreq-hw.c
> index a2be0df7e174..0138b2ec406d 100644
> --- a/drivers/cpufreq/qcom-cpufreq-hw.c
> +++ b/drivers/cpufreq/qcom-cpufreq-hw.c
> @@ -304,7 +304,8 @@ static void qcom_lmh_dcvs_notify(struct qcom_cpufreq_data *data)
>   	if (capacity > max_capacity)
>   		capacity = max_capacity;
>   
> -	arch_set_thermal_pressure(policy->cpus, max_capacity - capacity);
> +	arch_set_thermal_pressure(policy->related_cpus,
> +				  max_capacity - capacity);
>   
>   	/*
>   	 * In the unlikely case policy is unregistered do not enable
> 

-- 
Warm Regards
Thara (She/Her/Hers)