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Message-ID: <80debf449017604657abd9086d81b8cfc0e0ad5e.camel@surriel.com>
Subject: Re: [PATCH 5/8] sched,cfs: use explicit cfs_rq of parent se helper
From:   Rik van Riel <riel@surriel.com>
To:     Dietmar Eggemann <dietmar.eggemann@arm.com>, peterz@infradead.org
Cc:     mingo@redhat.com, linux-kernel@vger.kernel.org, kernel-team@fb.com,
        morten.rasmussen@arm.com, tglx@linutronix.de,
        mgorman@techsingularity.com, vincent.guittot@linaro.org
Date:   Wed, 26 Jun 2019 12:15:05 -0400
In-Reply-To: <0032016d-78d1-8338-96af-3077d3219f47@arm.com>
References: <20190612193227.993-1-riel@surriel.com>
         <20190612193227.993-6-riel@surriel.com>
         <0032016d-78d1-8338-96af-3077d3219f47@arm.com>
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On Wed, 2019-06-26 at 17:58 +0200, Dietmar Eggemann wrote:
> On 6/12/19 9:32 PM, Rik van Riel wrote:
> > Use an explicit "cfs_rq of parent sched_entity" helper in a few
> > strategic places, where cfs_rq_of(se) may no longer point at the
> > right runqueue once we flatten the hierarchical cgroup runqueues.
> >=20
> > No functional change.
> >=20
> > Signed-off-by: Rik van Riel <riel@surriel.com>
> > ---
> >  kernel/sched/fair.c | 17 +++++++++++++----
> >  1 file changed, 13 insertions(+), 4 deletions(-)
> >=20
> > diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> > index dcc521d251e3..c6ede2ecc935 100644
> > --- a/kernel/sched/fair.c
> > +++ b/kernel/sched/fair.c
> > @@ -275,6 +275,15 @@ static inline struct cfs_rq
> > *group_cfs_rq(struct sched_entity *grp)
> >  	return grp->my_q;
> >  }
> > =20
> > +/* runqueue owned by the parent entity */
> > +static inline struct cfs_rq *group_cfs_rq_of_parent(struct
> > sched_entity *se)
> > +{
> > +	if (se->parent)
> > +		return group_cfs_rq(se->parent);
> > +
> > +	return &cfs_rq_of(se)->rq->cfs;
>=20
> The function name and the description is not 100% correct. For tasks
> running naturally (not in a flattened taskgroup) in the root
> taskgroup
> or for the se representing a first level taskgroup (e.g. /tg1 (with
> se->depth =3D 0)) it returns the root cfs_rq or easier se->cfs_rq.
>=20
> So you could replace
>=20
>     return &cfs_rq_of(se)->rq->cfs;
>=20
> with
>=20
>     return se->cfs_rq;
>=20
> or
>=20
>     return cfs_rq_of(se);

Good point. I will do that for the v2 series.


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