On 17/06/16 09:49, Steven Rostedt wrote: > On Fri, 17 Jun 2016 10:48:41 +0100 > Juri Lelli <[email protected]> wrote: > > > setup_new_dl_entity() takes two parameters, but it only actually uses > > one of them to setup a new dl_entity. > > > > Actually this patch is making it so that setup_new_dl_entity() only > uses one of the parameters. Can you note why that change happened. > Because this change log implies that the second parameter wasn't used > before this patch, and that is incorrect. >
True, but we were practically already using the same parameter, under a different name though, after 2f9f3fdc928 "sched/deadline: Remove dl_new from struct sched_dl_entity" as we currently do: setup_new_dl_entity(&p->dl, &p->dl) > This patch reverts part of the change done in > commit 2d3d891d334 "sched/deadline: Add SCHED_DEADLINE inheritance > logic" > Before Luca's change we were doing setup_new_dl_entity(dl_se, pi_se) in update_dl_entity() for a dl_se->new entity. So, I guess the question is actually why we wanted to use pi_se's parameters (the potential PI donor) for setting up a new entity? Maybe we broke the situation where a task is currently boosted by a DEADLINE waiter and we swich the holder to DEADLINE? > It would be nice to have the reason in the change log. > Thanks a lot for pointing out what might be more than inaccuracy in the changelog. Best, - Juri > > > Remove the second, useless, parameter. > > > > Cc: Ingo Molnar <[email protected]> > > Cc: Peter Zijlstra <[email protected]> > > Cc: Steven Rostedt <[email protected]> > > Cc: Luca Abeni <[email protected]> > > Signed-off-by: Juri Lelli <[email protected]> > > --- > > kernel/sched/deadline.c | 9 ++++----- > > 1 file changed, 4 insertions(+), 5 deletions(-) > > > > diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c > > index fcb7f0217ff4..5229788a4765 100644 > > --- a/kernel/sched/deadline.c > > +++ b/kernel/sched/deadline.c > > @@ -346,8 +346,7 @@ static void check_preempt_curr_dl(struct rq *rq, struct > > task_struct *p, > > * one, and to (try to!) reconcile itself with its own scheduling > > * parameters. > > */ > > -static inline void setup_new_dl_entity(struct sched_dl_entity *dl_se, > > - struct sched_dl_entity *pi_se) > > +static inline void setup_new_dl_entity(struct sched_dl_entity *dl_se) > > { > > struct dl_rq *dl_rq = dl_rq_of_se(dl_se); > > struct rq *rq = rq_of_dl_rq(dl_rq); > > @@ -367,8 +366,8 @@ static inline void setup_new_dl_entity(struct > > sched_dl_entity *dl_se, > > * future; in fact, we must consider execution overheads (time > > * spent on hardirq context, etc.). > > */ > > - dl_se->deadline = rq_clock(rq) + pi_se->dl_deadline; > > - dl_se->runtime = pi_se->dl_runtime; > > + dl_se->deadline = rq_clock(rq) + dl_se->dl_deadline; > > + dl_se->runtime = dl_se->dl_runtime; > > } > > > > /* > > @@ -1721,7 +1720,7 @@ static void switched_from_dl(struct rq *rq, struct > > task_struct *p) > > static void switched_to_dl(struct rq *rq, struct task_struct *p) > > { > > if (dl_time_before(p->dl.deadline, rq_clock(rq))) > > - setup_new_dl_entity(&p->dl, &p->dl); > > + setup_new_dl_entity(&p->dl); > > > > if (task_on_rq_queued(p) && rq->curr != p) { > > #ifdef CONFIG_SMP >
