linux-kernel - Re: [PATCH] cpufreq: schedutil: Update last_update from sugov_set_iowait

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Date:   Tue, 18 Jul 2017 16:55:50 +0530
From:   Viresh Kumar <viresh.kumar@...aro.org>
To:     Juri Lelli <Juri.Lelli@....com>
Cc:     Rafael Wysocki <rjw@...ysocki.net>, Ingo Molnar <mingo@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        linux-pm@...r.kernel.org,
        Vincent Guittot <vincent.guittot@...aro.org>,
        joelaf@...gle.com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] cpufreq: schedutil: Update last_update from
 sugov_set_iowait_boost()

On 18-07-17, 12:20, Juri Lelli wrote:
> Hi Viresh,
> 
> On 18/07/17 10:24, Viresh Kumar wrote:
> > sg_cpu->last_update is always updated right after we call
> > sugov_set_iowait_boost() and its better to update it from that routine
> > itself. This makes it more readable.
> > 
> > Signed-off-by: Viresh Kumar <viresh.kumar@...aro.org>
> > ---
> >  kernel/sched/cpufreq_schedutil.c | 4 ++--
> >  1 file changed, 2 insertions(+), 2 deletions(-)
> > 
> > diff --git a/kernel/sched/cpufreq_schedutil.c b/kernel/sched/cpufreq_schedutil.c
> > index 29a397067ffa..63557b9f36b6 100644
> > --- a/kernel/sched/cpufreq_schedutil.c
> > +++ b/kernel/sched/cpufreq_schedutil.c
> > @@ -177,6 +177,8 @@ static void sugov_set_iowait_boost(struct sugov_cpu *sg_cpu, u64 time,
> >  		if (delta_ns > TICK_NSEC)
> >  			sg_cpu->iowait_boost = 0;
> >  	}
> > +
> > +	sg_cpu->last_update = time;
> >  }
> >  
> >  static void sugov_iowait_boost(struct sugov_cpu *sg_cpu, unsigned long *util,
> > @@ -219,7 +221,6 @@ static void sugov_update_single(struct update_util_data *hook, u64 time,
> >  	bool busy;
> >  
> >  	sugov_set_iowait_boost(sg_cpu, time, flags);
> > -	sg_cpu->last_update = time;
> >  
> >  	if (!sugov_should_update_freq(sg_policy, time))
> >  		return;
> > @@ -299,7 +300,6 @@ static void sugov_update_shared(struct update_util_data *hook, u64 time,
> >  	sg_cpu->flags = flags;
> >  
> >  	sugov_set_iowait_boost(sg_cpu, time, flags);
> > -	sg_cpu->last_update = time;
> 
> It actually belongs here, IMHO. We update other fields (util, max,
> flags)

Yeah, because they have bigger roles and aren't specific to iowait
boost.

> before looking at iowait. Why hiding the time update into a
> function dealing with only one of such fields?

But last_update is very much specific to iowait_boost only and so it
should be updated from sugov_set_iowait_boost() IMHO.

-- 
viresh