Messages in this thread Patch in this message | | | Date | Mon, 24 Feb 2020 12:31:23 +0000 | From | Qais Yousef <> | Subject | Re: [PATCH v2 6/6] sched/rt: Remove unnecessary assignment in inc/dec_rt_migration |
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On 02/24/20 00:16, Dietmar Eggemann wrote: > On 23.02.20 19:40, Qais Yousef wrote: > > The statement > > > > rt_rq = &rq_of_rt_rq(rt_rq)->rt > > > > Was just dereferencing rt_rq to get a pointer to itself. Which is a NOP. > > Remove it. > > > > Signed-off-by: Qais Yousef <qais.yousef@arm.com> > > --- > > kernel/sched/rt.c | 2 -- > > 1 file changed, 2 deletions(-) > > > > diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c > > index b35e49cdafcc..520e84993fe7 100644 > > --- a/kernel/sched/rt.c > > +++ b/kernel/sched/rt.c > > @@ -343,7 +343,6 @@ static void inc_rt_migration(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq) > > return; > > > > p = rt_task_of(rt_se); > > - rt_rq = &rq_of_rt_rq(rt_rq)->rt; > > IMHO, this is here to get the root rt_rq from any rt_rq (task_groups). > Looks like that e.g rt_nr_total is only maintained on root rt_rq's. > > Similar to CFS' &rq_of(cfs_rq)->cfs (cfs_rq_util_change()) to get root > cfs_rq. > > Not sure where CONFIG_RT_GROUP_SCHED=y is used but it's part of the rt > class implementation.
Ah I see. That was obvious.. How about the below comment?
This code is executed only if rt_entity_is_task(), I don't think this grantees that the rt_rq isn't for a group?
I need to go and unravel the layers maybe.
Thanks!
-- Qais Yousef
-->8--
diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c index b35e49cdafcc..f929867215c4 100644 --- a/kernel/sched/rt.c +++ b/kernel/sched/rt.c @@ -343,6 +343,8 @@ static void inc_rt_migration(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq) return;
p = rt_task_of(rt_se); + + /* get the root rt_rq if this is the rt_rq of a group */ rt_rq = &rq_of_rt_rq(rt_rq)->rt;
rt_rq->rt_nr_total++; @@ -368,6 +370,8 @@ static void dec_rt_migration(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq) return;
p = rt_task_of(rt_se); + + /* get the root rt_rq if this is the rt_rq of a group */ rt_rq = &rq_of_rt_rq(rt_rq)->rt;
rt_rq->rt_nr_total--;
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