linux-kernel - Re: [PATCH 3/8] sched/fair: Tweak misfit-related capacity checks

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Message-ID: <jhjmtwl2dsc.mognet@arm.com>
Date:   Wed, 03 Feb 2021 18:42:59 +0000
From:   Valentin Schneider <valentin.schneider@....com>
To:     Qais Yousef <qais.yousef@....com>
Cc:     linux-kernel@...r.kernel.org,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...nel.org>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Dietmar Eggemann <dietmar.eggemann@....com>,
        Morten Rasmussen <morten.rasmussen@....com>,
        Quentin Perret <qperret@...gle.com>,
        Pavan Kondeti <pkondeti@...eaurora.org>,
        Rik van Riel <riel@...riel.com>
Subject: Re: [PATCH 3/8] sched/fair: Tweak misfit-related capacity checks

On 03/02/21 15:15, Qais Yousef wrote:
> On 01/28/21 18:31, Valentin Schneider wrote:
>> @@ -113,6 +113,13 @@ int __weak arch_asym_cpu_priority(int cpu)
>>   */
>>  #define fits_capacity(cap, max)	((cap) * 1280 < (max) * 1024)
>>  
>> +/*
>> + * The margin used when comparing CPU capacities.
>> + * is 'cap' noticeably greater than 'ref'
>> + *
>> + * (default: ~5%)
>> + */
>> +#define capacity_greater(cap, ref) ((ref) * 1078 < (cap) * 1024)
>
> nit: can we use cap1 and cap2 and make the implementation use '>' instead of
> '<'? ie:
>
> 	#define capacity_greater(cap1, cap2) ((cap1) * 1024 > (cap2) * 1078)
>
> this is more intuitive to read IMHO. Especially few lines below we have
>
> 	return capacity_greater(ref->sgc->max_capacity, sg->sgc->max_capacity);
>
> which pass 'ref->...' as cap which can be confusing when looking at the
> function signature @ref.
>

Unfortunate naming indeed... And I suppose it can't hurt to follow the
argument "declaration" order.