linux-kernel - Re: [RFC PATCH 2/5] sched/events: Introduce cfs

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Message-ID: <20170328172005.GF11362@e110439-lin>
Date:   Tue, 28 Mar 2017 18:20:05 +0100
From:   Patrick Bellasi <patrick.bellasi@....com>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     Steven Rostedt <rostedt@...dmis.org>,
        Dietmar Eggemann <dietmar.eggemann@....com>,
        Ingo Molnar <mingo@...nel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Matt Fleming <matt@...eblueprint.co.uk>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Morten Rasmussen <morten.rasmussen@....com>,
        Juri Lelli <juri.lelli@....com>
Subject: Re: [RFC PATCH 2/5] sched/events: Introduce cfs_rq load tracking
 trace event

On 28-Mar 18:57, Peter Zijlstra wrote:
> On Tue, Mar 28, 2017 at 06:44:59PM +0200, Peter Zijlstra wrote:
> > ---
> > --- a/kernel/sched/fair.c
> > +++ b/kernel/sched/fair.c
> > @@ -2849,7 +2849,7 @@ static u32 __compute_runnable_contrib(u6
> >   *            = u_0 + u_1*y + u_2*y^2 + ... [re-labeling u_i --> u_{i+1}]
> >   */
> >  static __always_inline int
> > -__update_load_avg(u64 now, int cpu, struct sched_avg *sa,
> > +___update_load_avg(u64 now, int cpu, struct sched_avg *sa,
> >  		  unsigned long weight, int running, struct cfs_rq *cfs_rq)
> >  {
> >  	u64 delta, scaled_delta, periods;
> > @@ -2953,6 +2953,26 @@ __update_load_avg(u64 now, int cpu, stru
> >  	return decayed;
> >  }
> >  
> > +static int
> > +__update_load_avg_blocked_se(u64 now, int cpu, struct sched_avg *sa)
> > +{
> > +	return ___update_load_avg(now, cpu, sa, 0, 0, NULL);
> > +}
> > +
> > +static int
> > +__update_load_avg_se(u64 now, int cpu, struct sched_avg *sa,
> > +		     unsigned long weight, int running)
> > +{
> > +	return ___update_load_avg(now, cpu, sa, weight, running, NULL);
> > +}
> > +
> > +static int
> > +__update_load_avg(u64 now, int cpu, struct sched_avg *sa,
> > +		  unsigned long weight, int running, struct cfs_rq *cfs_rq)

                  __attribute__((nonnull (6)));

> > +{
> > +	return ___update_load_avg(now, cpu, sa, weight, running, cfs_rq);
> 
> Although ideally we'd be able to tell the compiler that cfs_rq will not
> be NULL here. Hurmph.. no __builtin for that I think :/

What about the above attribute?

> 
> > +}

-- 
#include <best/regards.h>

Patrick Bellasi