linux-kernel - Re: [Patch v6 2/7] sched: Add hook to read per cpu thermal pressure.

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Message-ID: <51954bed-6981-2f7d-1618-128e291a5c22@arm.com>
Date:   Tue, 17 Dec 2019 13:54:23 +0100
From:   Dietmar Eggemann <dietmar.eggemann@....com>
To:     Peter Zijlstra <peterz@...radead.org>,
        Thara Gopinath <thara.gopinath@...aro.org>
Cc:     mingo@...hat.com, ionela.voinescu@....com,
        vincent.guittot@...aro.org, rui.zhang@...el.com,
        qperret@...gle.com, daniel.lezcano@...aro.org,
        viresh.kumar@...aro.org, linux-kernel@...r.kernel.org,
        amit.kachhap@...il.com, javi.merino@...nel.org,
        amit.kucheria@...durent.com
Subject: Re: [Patch v6 2/7] sched: Add hook to read per cpu thermal pressure.

On 16/12/2019 15:35, Peter Zijlstra wrote:
> On Wed, Dec 11, 2019 at 11:11:43PM -0500, Thara Gopinath wrote:

minor: in subject: s/sched/sched/topology


>> Introduce arch_scale_thermal_capacity to retrieve per cpu thermal
>> pressure.
>>
>> Signed-off-by: Thara Gopinath <thara.gopinath@...aro.org>
>> ---
>>  include/linux/sched/topology.h | 8 ++++++++
>>  1 file changed, 8 insertions(+)
>>
>> diff --git a/include/linux/sched/topology.h b/include/linux/sched/topology.h
>> index f341163..f1e22f9 100644
>> --- a/include/linux/sched/topology.h
>> +++ b/include/linux/sched/topology.h
>> @@ -225,6 +225,14 @@ unsigned long arch_scale_cpu_capacity(int cpu)
>>  }
>>  #endif
>>  
>> +#ifndef arch_scale_thermal_capacity
>> +static __always_inline
>> +unsigned long arch_scale_thermal_capacity(int cpu)
>> +{
>> +	return 0;
>> +}
>> +#endif
> 
> This is confusing, the return value is not a capacity, it is a reduction
> in capacity. Either a comment of a better name would be appreciated.

+1, the patch-set uses: thermal_capacity, thermal_pressure,
capped_capacity.