linux-kernel - Re: [RFC PATCH v4 05/12] sched/topology: Reference the Energy Model of CPUs when available

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Message-ID: <20180705174809.GA21903@e108498-lin.cambridge.arm.com>
Date:   Thu, 5 Jul 2018 18:48:09 +0100
From:   Quentin Perret <quentin.perret@....com>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     rjw@...ysocki.net, linux-kernel@...r.kernel.org,
        linux-pm@...r.kernel.org, gregkh@...uxfoundation.org,
        mingo@...hat.com, dietmar.eggemann@....com,
        morten.rasmussen@....com, chris.redpath@....com,
        patrick.bellasi@....com, valentin.schneider@....com,
        vincent.guittot@...aro.org, thara.gopinath@...aro.org,
        viresh.kumar@...aro.org, tkjos@...gle.com, joel@...lfernandes.org,
        smuckle@...gle.com, adharmap@...cinc.com, skannan@...cinc.com,
        pkondeti@...eaurora.org, juri.lelli@...hat.com,
        edubezval@...il.com, srinivas.pandruvada@...ux.intel.com,
        currojerez@...eup.net, javi.merino@...nel.org
Subject: Re: [RFC PATCH v4 05/12] sched/topology: Reference the Energy Model
 of CPUs when available

On Thursday 05 Jul 2018 at 19:29:22 (+0200), Peter Zijlstra wrote:
> On Thu, Jun 28, 2018 at 12:40:36PM +0100, Quentin Perret wrote:
> >  static void free_rootdomain(struct rcu_head *rcu)
> >  {
> >  	struct root_domain *rd = container_of(rcu, struct root_domain, rcu);
> > @@ -211,6 +224,9 @@ static void free_rootdomain(struct rcu_head *rcu)
> >  	free_cpumask_var(rd->rto_mask);
> >  	free_cpumask_var(rd->online);
> >  	free_cpumask_var(rd->span);
> > +#ifdef CONFIG_ENERGY_MODEL
> > +	free_fd(rd->fd);
> > +#endif
> 
> If you provide a stub function, you can reduce #ifdef.

I cannot just stub free_fd since the 'fd' member of the root_domain is
also defined only for CONFIG_ENERGY_MODEL=y.

But I can introduce a free_rd_fd(fd) function that will be stubbed if
you think that's better. Or make sure to have 'fd' attached to the
root_domain even for CONFIG_ENERGY_MODEL=n.

> 
> >  	kfree(rd);
> >  }
> >  
> > @@ -1635,6 +1651,104 @@ static struct sched_domain *build_sched_domain(struct sched_domain_topology_leve
> >  	return sd;
> >  }
> >  
> > +#ifdef CONFIG_ENERGY_MODEL
> 
>   < snip content >
> 
> > +#endif
> 
> And is there any reason this #ifdef cannot be merged with the one above?

Not really, it was just easier to keep build_freq_domains() close to
partition_sched_domains() while writing/reading the code but that is
a very weak argument, I agree. I'll move all of that to the ifdef above.

> That is, try and do a pass of #ifdef reduction on this file.

Ok I'll look into that.

Thanks,
Quentin