linux-kernel - Re: [PATCH] cpufreq: schedutil: Move max CPU capacity to sugov

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Message-ID: <20e4ffb8-905a-92e2-8ea2-6116e8031dac@arm.com>
Date:   Tue, 12 Jul 2022 11:07:06 +0100
From:   Lukasz Luba <lukasz.luba@....com>
To:     Viresh Kumar <viresh.kumar@...aro.org>
Cc:     linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org,
        rafael@...nel.org, dietmar.eggemann@....com,
        vincent.guittot@...aro.org
Subject: Re: [PATCH] cpufreq: schedutil: Move max CPU capacity to sugov_policy



On 7/12/22 09:41, Viresh Kumar wrote:
> On 11-07-22, 13:42, Lukasz Luba wrote:
>> There is no need to keep the max CPU capacity in the per_cpu instance.
>> Furthermore, there is no need to check and update that variable
>> (sg_cpu->max) everytime in the frequency change request, which is part
>> of hot path. Instead use struct sugov_policy to store that information.
>> Initialize the max CPU capacity during the setup and start callback.
>> We can do that since all CPUs in the same frequency domain have the same
>> max capacity (capacity setup and thermal pressure are based on that).
>>
>> Signed-off-by: Lukasz Luba <lukasz.luba@....com>
>> ---
>>   kernel/sched/cpufreq_schedutil.c | 30 +++++++++++++++---------------
>>   1 file changed, 15 insertions(+), 15 deletions(-)
> 
> I tried to check all possible combinations on how this can break, but
> couldn't find one. I had to check that as this code is there since
> ages and none of us thought of it, which was surprising.

I thought the same.

> 
> Acked-by: Viresh Kumar <viresh.kumar@...aro.org>
> 

Thanks for the ACK!