linux-kernel - Re: [PATCH 3/5] sched/fair: Make select_idle

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Message-ID: <20210118092743.GP3592@techsingularity.net>
Date:   Mon, 18 Jan 2021 09:27:43 +0000
From:   Mel Gorman <mgorman@...hsingularity.net>
To:     "Li, Aubrey" <aubrey.li@...ux.intel.com>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Qais Yousef <qais.yousef@....com>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 3/5] sched/fair: Make select_idle_cpu() proportional to
 cores

On Mon, Jan 18, 2021 at 04:14:36PM +0800, Li, Aubrey wrote:
> > <SNIP>
> > @@ -6124,6 +6126,8 @@ static int select_idle_smt(struct task_struct *p, struct sched_domain *sd, int t
> >  
> >  #else /* CONFIG_SCHED_SMT */
> >  
> > +#define sched_smt_weight	1
> > +
> >  static inline int select_idle_core(struct task_struct *p, struct sched_domain *sd, int target)
> >  {
> >  	return -1;
> >
> > <SNIP>
> >
> > @@ -6166,10 +6172,12 @@ static int select_idle_cpu(struct task_struct *p, struct sched_domain *sd, int t
> >  		avg_cost = this_sd->avg_scan_cost + 1;
> >  
> >  		span_avg = sd->span_weight * avg_idle;
> > -		if (span_avg > 4*avg_cost)
> > +		if (span_avg > sis_min_cores*avg_cost)
> >  			nr = div_u64(span_avg, avg_cost);
> >  		else
> > -			nr = 4;
> > +			nr = sis_min_cores;
> > +
> > +		nr *= sched_smt_weight;
> 
> Is it better to put this into an inline wrapper to hide sched_smt_weight if !CONFIG_SCHED_SMT?
> 

There already is a #define sched_smt_weight for !CONFIG_SCHED_SMT and I
do not think an inline wrapper would make it more readable or maintainable.

-- 
Mel Gorman
SUSE Labs