Re: [PATCH] sched: Transform resched_task() into resched_curr()

Re: [PATCH] sched: Transform resched_task() into resched_curr()

[Andreas Mohr]

Hi,

I cannot speak too much about scheduler specifics, but from a structural POV
I'm unsure about such a change (into this direction).

We seem to be going from a nicely fine-grained function
(task-struct-specific, and thus operating on task scope alone,
except for interesting lockdep_assert_held() outer-env validation-only parts)
to one which has a *broader* scope (namely, wholly rq-parameterized),
thus now drawing the rq dependency into the equation:
this patch introduces access to rq->curr specifics *within
function implementation* (as the first measure within a function,
which in itself might be considered a smell),
and it needlessly widens the scope of concerns of this handler
by now enabling full access to any rq struct members there -
we'll then end up with the next guy introducing
some strange dependency on other rq parts within this handler
which that guy would not have been tempted to do in the first place
if it had remained strictly task-based......

I'd wager that the size benefit possibly dominantly stems from
getting rid of rq->curr indirection lookup at the many user call sites.
Thus it might be a good idea
to instead create a non-inlined resched_curr() wrapper
which merely forwards to resched_task(),
to have the currently strictly task-focussed (pun intended ;) approach
of resched_task() properly preserved.

Generally spoken, this incident and the "interesting" status quo
of very often doing an open-coded rq->curr lookup when calling resched_task()
could prompt a rethinking of relationship of task vs. rq,
since by clearing up (and focussing on) design intentions,
one could "automatically" end up
with more elegant and thus better function implementations.


Thank you for your activities in the scheduler area!

Andreas Mohr

Re: [PATCH] sched: Transform resched_task() into resched_curr()

[Kirill Tkhai]

Hi, Andreas,

On 29.06.2014 11:20, Andreas Mohr wrote:
> Hi,
> 
> I cannot speak too much about scheduler specifics, but from a structural POV
> I'm unsure about such a change (into this direction).
> 
> We seem to be going from a nicely fine-grained function
> (task-struct-specific, and thus operating on task scope alone,
> except for interesting lockdep_assert_held() outer-env validation-only parts)
> to one which has a *broader* scope (namely, wholly rq-parameterized),
> thus now drawing the rq dependency into the equation:
> this patch introduces access to rq->curr specifics *within
> function implementation* (as the first measure within a function,
> which in itself might be considered a smell),
> and it needlessly widens the scope of concerns of this handler
> by now enabling full access to any rq struct members there -
> we'll then end up with the next guy introducing
> some strange dependency on other rq parts within this handler
> which that guy would not have been tempted to do in the first place
> if it had remained strictly task-based......
> 
> I'd wager that the size benefit possibly dominantly stems from
> getting rid of rq->curr indirection lookup at the many user call sites.
> Thus it might be a good idea
> to instead create a non-inlined resched_curr() wrapper
> which merely forwards to resched_task(),
> to have the currently strictly task-focussed (pun intended ;) approach
> of resched_task() properly preserved.
> 
> Generally spoken, this incident and the "interesting" status quo
> of very often doing an open-coded rq->curr lookup when calling resched_task()
> could prompt a rethinking of relationship of task vs. rq,
> since by clearing up (and focussing on) design intentions,
> one could "automatically" end up
> with more elegant and thus better function implementations.

resched_curr(rq) means "to reschedule current task of the rq". It does
not reschedule rq itself.

We already have resched_cpu(), which has cpu agrument, and it's not
a task. I think this is just a similar case and we won't have any
problems because of this.

We only can reschedule the current task, and the patch underlines that fact.

> 
> 
> Thank you for your activities in the scheduler area!
> 
> Andreas Mohr
> 

Thanks,
Kirill

Re: [PATCH] sched: Transform resched_task() into resched_curr()

[Andreas Mohr]

Hi,

On Sun, Jun 29, 2014 at 11:57:49AM +0400, Kirill Tkhai wrote:
> resched_curr(rq) means "to reschedule current task of the rq". It does
> not reschedule rq itself.
> 
> We already have resched_cpu(), which has cpu agrument, and it's not
> a task. I think this is just a similar case and we won't have any
> problems because of this.
> 
> We only can reschedule the current task, and the patch underlines that fact.

OK. I was arguing almost purely mechanically, and from a mechanical POV
I had some doubts.

I just noticed that there is a part touching rq->idle,
and ISTR that idle task handling is "special"
(after all that's the power management side of things).
Specifically, rq->curr and rq->idle are distinct rq members
(since they are distinct tasks AFAIK!),
so there might now be some issues with task state tracking here
(unless this cleanup happens to unify handling here anyway).

Thanks,

Andreas Mohr

Re: [PATCH] sched: Transform resched_task() into resched_curr()

[Kirill Tkhai]

On 29.06.2014 12:36, Andreas Mohr wrote:
> Hi,
> 
> On Sun, Jun 29, 2014 at 11:57:49AM +0400, Kirill Tkhai wrote:
>> resched_curr(rq) means "to reschedule current task of the rq". It does
>> not reschedule rq itself.
>>
>> We already have resched_cpu(), which has cpu agrument, and it's not
>> a task. I think this is just a similar case and we won't have any
>> problems because of this.
>>
>> We only can reschedule the current task, and the patch underlines that fact.
> 
> OK. I was arguing almost purely mechanically, and from a mechanical POV
> I had some doubts.
> 
> I just noticed that there is a part touching rq->idle,
> and ISTR that idle task handling is "special"
> (after all that's the power management side of things).
> Specifically, rq->curr and rq->idle are distinct rq members
> (since they are distinct tasks AFAIK!),
> so there might now be some issues with task state tracking here
> (unless this cleanup happens to unify handling here anyway).

Are you worrying about check_preempt_curr_idle()? I've looked
at check_preempt_curr() and found, we never call this function
in current scheduler logic.

It's called only if just enqueued task is of the same class as
rq's current, but we can't have two idle class tasks enqueued
on the same rq. So, it's just a stub. We can do not worry
about this.

Thanks,
Kirill

Re: [PATCH] sched: Transform resched_task() into resched_curr()

[Andreas Mohr]

On Sun, Jun 29, 2014 at 12:59:41PM +0400, Kirill Tkhai wrote:
> On 29.06.2014 12:36, Andreas Mohr wrote:
> > I just noticed that there is a part touching rq->idle,
> > and ISTR that idle task handling is "special"
> > (after all that's the power management side of things).
> > Specifically, rq->curr and rq->idle are distinct rq members
> > (since they are distinct tasks AFAIK!),
> > so there might now be some issues with task state tracking here
> > (unless this cleanup happens to unify handling here anyway).
> 
> Are you worrying about check_preempt_curr_idle()? I've looked
> at check_preempt_curr() and found, we never call this function
> in current scheduler logic.

Yeah - I should have included that hunk verbatim, sorry.


> It's called only if just enqueued task is of the same class as
> rq's current, but we can't have two idle class tasks enqueued
> on the same rq. So, it's just a stub. We can do not worry
> about this.

That seems to be the case indeed in current implementation.

Removing specific references from these sched_class parts
(here: idle_task.c, rq->idle) where possible seems to be a good direction,
since AFAIUI sched_class things are supposed to encode *behaviour*,
where containing too many specific-member references is best avoided.



I'd fathom that for the sched_curr() handler
I'm still somewhat in favour of an extra non-inline wrapper though;
it's just good minimal-dependency implementation.
But more frequent topic partners might have more valuable input
on this patch :)

Thanks,

Andreas

[PATCH] sched: Transform resched_task() into resched_curr()

[Kirill Tkhai]

We always use resched_task() with rq->curr argument.
It's not possible to reschedule any task but rq's current.

The patch introduces resched_curr(struct rq *) to
replace all of the repeating patterns. The main aim
is cleanup, but there is a little size profit too:

(before)
$ size kernel/sched/built-in.o
   text	   data	    bss	    dec	    hex	filename
155274	  16445	   7042	 178761	  2ba49	kernel/sched/built-in.o

$ size vmlinux
   text	   data	    bss	    dec	    hex	filename
7411490	1178376	 991232	9581098	 92322a	vmlinux

(after)
$ size kernel/sched/built-in.o
   text	   data	    bss	    dec	    hex	filename
155130	  16445	   7042	 178617	  2b9b9	kernel/sched/built-in.o

$ size vmlinux
   text	   data	    bss	    dec	    hex	filename
7411362	1178376	 991232	9580970	 9231aa	vmlinux

I was choosing between resched_curr() and resched_rq(),
and the first name looks better for me.

A little lie in Documentation/trace/ftrace.txt. I have not
actually collected the tracing again. With a hope the patch
won't make execution times much worse :)

Signed-off-by: Kirill Tkhai <tkhai@yandex.ru>
CC: Peter Zijlstra <peterz@infradead.org>
CC: Ingo Molnar <mingo@kernel.org>
---
 Documentation/trace/ftrace.txt |    2 +-
 include/linux/sched.h          |    6 +++---
 kernel/sched/core.c            |   25 +++++++++++++------------
 kernel/sched/deadline.c        |   16 ++++++++--------
 kernel/sched/fair.c            |   20 ++++++++++----------
 kernel/sched/idle_task.c       |    2 +-
 kernel/sched/rt.c              |   27 ++++++++++++++-------------
 kernel/sched/sched.h           |    2 +-
 8 files changed, 51 insertions(+), 49 deletions(-)

diff --git a/Documentation/trace/ftrace.txt b/Documentation/trace/ftrace.txt
index 2479b2a..4da4261 100644
--- a/Documentation/trace/ftrace.txt
+++ b/Documentation/trace/ftrace.txt
@@ -1515,7 +1515,7 @@ Doing the same with chrt -r 5 and function-trace set.
   <idle>-0       3d.h4    1us+:      0:120:R   + [003]  2448: 94:R sleep
   <idle>-0       3d.h4    2us : ttwu_do_activate.constprop.87 <-try_to_wake_up
   <idle>-0       3d.h3    3us : check_preempt_curr <-ttwu_do_wakeup
-  <idle>-0       3d.h3    3us : resched_task <-check_preempt_curr
+  <idle>-0       3d.h3    3us : resched_curr <-check_preempt_curr
   <idle>-0       3dNh3    4us : task_woken_rt <-ttwu_do_wakeup
   <idle>-0       3dNh3    4us : _raw_spin_unlock <-try_to_wake_up
   <idle>-0       3dNh3    4us : sub_preempt_count <-_raw_spin_unlock
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 306f4f0..9d177b8 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -2788,7 +2788,7 @@ static inline bool __must_check current_set_polling_and_test(void)
 
 	/*
 	 * Polling state must be visible before we test NEED_RESCHED,
-	 * paired by resched_task()
+	 * paired by resched_curr()
 	 */
 	smp_mb__after_atomic();
 
@@ -2806,7 +2806,7 @@ static inline bool __must_check current_clr_polling_and_test(void)
 
 	/*
 	 * Polling state must be visible before we test NEED_RESCHED,
-	 * paired by resched_task()
+	 * paired by resched_curr()
 	 */
 	smp_mb__after_atomic();
 
@@ -2838,7 +2838,7 @@ static inline void current_clr_polling(void)
 	 * TIF_NEED_RESCHED and the IPI handler, scheduler_ipi(), will also
 	 * fold.
 	 */
-	smp_mb(); /* paired with resched_task() */
+	smp_mb(); /* paired with resched_curr() */
 
 	preempt_fold_need_resched();
 }
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index ceea8d0..8da054f 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -587,30 +587,31 @@ static bool set_nr_if_polling(struct task_struct *p)
 #endif
 
 /*
- * resched_task - mark a task 'to be rescheduled now'.
+ * resched_curr - mark rq's current task 'to be rescheduled now'.
  *
  * On UP this means the setting of the need_resched flag, on SMP it
  * might also involve a cross-CPU call to trigger the scheduler on
  * the target CPU.
  */
-void resched_task(struct task_struct *p)
+void resched_curr(struct rq *rq)
 {
+	struct task_struct *curr = rq->curr;
 	int cpu;
 
-	lockdep_assert_held(&task_rq(p)->lock);
+	lockdep_assert_held(&rq->lock);
 
-	if (test_tsk_need_resched(p))
+	if (test_tsk_need_resched(curr))
 		return;
 
-	cpu = task_cpu(p);
+	cpu = rq->cpu;
 
 	if (cpu == smp_processor_id()) {
-		set_tsk_need_resched(p);
+		set_tsk_need_resched(curr);
 		set_preempt_need_resched();
 		return;
 	}
 
-	if (set_nr_and_not_polling(p))
+	if (set_nr_and_not_polling(curr))
 		smp_send_reschedule(cpu);
 	else
 		trace_sched_wake_idle_without_ipi(cpu);
@@ -623,7 +624,7 @@ void resched_cpu(int cpu)
 
 	if (!raw_spin_trylock_irqsave(&rq->lock, flags))
 		return;
-	resched_task(cpu_curr(cpu));
+	resched_curr(rq);
 	raw_spin_unlock_irqrestore(&rq->lock, flags);
 }
 
@@ -1029,7 +1030,7 @@ void check_preempt_curr(struct rq *rq, struct task_struct *p, int flags)
 			if (class == rq->curr->sched_class)
 				break;
 			if (class == p->sched_class) {
-				resched_task(rq->curr);
+				resched_curr(rq);
 				break;
 			}
 		}
@@ -3068,7 +3069,7 @@ void set_user_nice(struct task_struct *p, long nice)
 		 * lowered its priority, then reschedule its CPU:
 		 */
 		if (delta < 0 || (delta > 0 && task_running(rq, p)))
-			resched_task(rq->curr);
+			resched_curr(rq);
 	}
 out_unlock:
 	task_rq_unlock(rq, p, &flags);
@@ -4289,7 +4290,7 @@ int __sched yield_to(struct task_struct *p, bool preempt)
 		 * fairness.
 		 */
 		if (preempt && rq != p_rq)
-			resched_task(p_rq->curr);
+			resched_curr(p_rq);
 	}
 
 out_unlock:
@@ -7096,7 +7097,7 @@ static void normalize_task(struct rq *rq, struct task_struct *p)
 	__setscheduler(rq, p, &attr);
 	if (on_rq) {
 		enqueue_task(rq, p, 0);
-		resched_task(rq->curr);
+		resched_curr(rq);
 	}
 
 	check_class_changed(rq, p, prev_class, old_prio);
diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
index fc4f98b1..df0b77a 100644
--- a/kernel/sched/deadline.c
+++ b/kernel/sched/deadline.c
@@ -535,7 +535,7 @@ static enum hrtimer_restart dl_task_timer(struct hrtimer *timer)
 		if (task_has_dl_policy(rq->curr))
 			check_preempt_curr_dl(rq, p, 0);
 		else
-			resched_task(rq->curr);
+			resched_curr(rq);
 #ifdef CONFIG_SMP
 		/*
 		 * Queueing this task back might have overloaded rq,
@@ -634,7 +634,7 @@ static void update_curr_dl(struct rq *rq)
 			enqueue_task_dl(rq, curr, ENQUEUE_REPLENISH);
 
 		if (!is_leftmost(curr, &rq->dl))
-			resched_task(curr);
+			resched_curr(rq);
 	}
 
 	/*
@@ -964,7 +964,7 @@ static void check_preempt_equal_dl(struct rq *rq, struct task_struct *p)
 	    cpudl_find(&rq->rd->cpudl, p, NULL) != -1)
 		return;
 
-	resched_task(rq->curr);
+	resched_curr(rq);
 }
 
 static int pull_dl_task(struct rq *this_rq);
@@ -979,7 +979,7 @@ static void check_preempt_curr_dl(struct rq *rq, struct task_struct *p,
 				  int flags)
 {
 	if (dl_entity_preempt(&p->dl, &rq->curr->dl)) {
-		resched_task(rq->curr);
+		resched_curr(rq);
 		return;
 	}
 
@@ -1333,7 +1333,7 @@ static int push_dl_task(struct rq *rq)
 	if (dl_task(rq->curr) &&
 	    dl_time_before(next_task->dl.deadline, rq->curr->dl.deadline) &&
 	    rq->curr->nr_cpus_allowed > 1) {
-		resched_task(rq->curr);
+		resched_curr(rq);
 		return 0;
 	}
 
@@ -1373,7 +1373,7 @@ static int push_dl_task(struct rq *rq)
 	set_task_cpu(next_task, later_rq->cpu);
 	activate_task(later_rq, next_task, 0);
 
-	resched_task(later_rq->curr);
+	resched_curr(later_rq);
 
 	double_unlock_balance(rq, later_rq);
 
@@ -1632,14 +1632,14 @@ static void prio_changed_dl(struct rq *rq, struct task_struct *p,
 		 */
 		if (dl_time_before(rq->dl.earliest_dl.curr, p->dl.deadline) &&
 		    rq->curr == p)
-			resched_task(p);
+			resched_curr(rq);
 #else
 		/*
 		 * Again, we don't know if p has a earlier
 		 * or later deadline, so let's blindly set a
 		 * (maybe not needed) rescheduling point.
 		 */
-		resched_task(p);
+		resched_curr(rq);
 #endif /* CONFIG_SMP */
 	} else
 		switched_to_dl(rq, p);
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 1f9c457..64f294b 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -2900,7 +2900,7 @@ check_preempt_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr)
 	ideal_runtime = sched_slice(cfs_rq, curr);
 	delta_exec = curr->sum_exec_runtime - curr->prev_sum_exec_runtime;
 	if (delta_exec > ideal_runtime) {
-		resched_task(rq_of(cfs_rq)->curr);
+		resched_curr(rq_of(cfs_rq));
 		/*
 		 * The current task ran long enough, ensure it doesn't get
 		 * re-elected due to buddy favours.
@@ -2924,7 +2924,7 @@ check_preempt_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr)
 		return;
 
 	if (delta > ideal_runtime)
-		resched_task(rq_of(cfs_rq)->curr);
+		resched_curr(rq_of(cfs_rq));
 }
 
 static void
@@ -3064,7 +3064,7 @@ entity_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr, int queued)
 	 * validating it and just reschedule.
 	 */
 	if (queued) {
-		resched_task(rq_of(cfs_rq)->curr);
+		resched_curr(rq_of(cfs_rq));
 		return;
 	}
 	/*
@@ -3255,7 +3255,7 @@ static void __account_cfs_rq_runtime(struct cfs_rq *cfs_rq, u64 delta_exec)
 	 * hierarchy can be throttled
 	 */
 	if (!assign_cfs_rq_runtime(cfs_rq) && likely(cfs_rq->curr))
-		resched_task(rq_of(cfs_rq)->curr);
+		resched_curr(rq_of(cfs_rq));
 }
 
 static __always_inline
@@ -3411,7 +3411,7 @@ void unthrottle_cfs_rq(struct cfs_rq *cfs_rq)
 
 	/* determine whether we need to wake up potentially idle cpu */
 	if (rq->curr == rq->idle && rq->cfs.nr_running)
-		resched_task(rq->curr);
+		resched_curr(rq);
 }
 
 static u64 distribute_cfs_runtime(struct cfs_bandwidth *cfs_b,
@@ -3855,7 +3855,7 @@ static void hrtick_start_fair(struct rq *rq, struct task_struct *p)
 
 		if (delta < 0) {
 			if (rq->curr == p)
-				resched_task(p);
+				resched_curr(rq);
 			return;
 		}
 
@@ -4724,7 +4724,7 @@ static void check_preempt_wakeup(struct rq *rq, struct task_struct *p, int wake_
 	return;
 
 preempt:
-	resched_task(curr);
+	resched_curr(rq);
 	/*
 	 * Only set the backward buddy when the current task is still
 	 * on the rq. This can happen when a wakeup gets interleaved
@@ -7398,7 +7398,7 @@ static void task_fork_fair(struct task_struct *p)
 		 * 'current' within the tree based on its new key value.
 		 */
 		swap(curr->vruntime, se->vruntime);
-		resched_task(rq->curr);
+		resched_curr(rq);
 	}
 
 	se->vruntime -= cfs_rq->min_vruntime;
@@ -7423,7 +7423,7 @@ prio_changed_fair(struct rq *rq, struct task_struct *p, int oldprio)
 	 */
 	if (rq->curr == p) {
 		if (p->prio > oldprio)
-			resched_task(rq->curr);
+			resched_curr(rq);
 	} else
 		check_preempt_curr(rq, p, 0);
 }
@@ -7486,7 +7486,7 @@ static void switched_to_fair(struct rq *rq, struct task_struct *p)
 	 * if we can still preempt the current task.
 	 */
 	if (rq->curr == p)
-		resched_task(rq->curr);
+		resched_curr(rq);
 	else
 		check_preempt_curr(rq, p, 0);
 }
diff --git a/kernel/sched/idle_task.c b/kernel/sched/idle_task.c
index 879f2b7..67ad4e7 100644
--- a/kernel/sched/idle_task.c
+++ b/kernel/sched/idle_task.c
@@ -20,7 +20,7 @@ select_task_rq_idle(struct task_struct *p, int cpu, int sd_flag, int flags)
  */
 static void check_preempt_curr_idle(struct rq *rq, struct task_struct *p, int flags)
 {
-	resched_task(rq->idle);
+	resched_curr(rq);
 }
 
 static struct task_struct *
diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c
index a490831..289eb94 100644
--- a/kernel/sched/rt.c
+++ b/kernel/sched/rt.c
@@ -463,9 +463,10 @@ static void dequeue_rt_entity(struct sched_rt_entity *rt_se);
 static void sched_rt_rq_enqueue(struct rt_rq *rt_rq)
 {
 	struct task_struct *curr = rq_of_rt_rq(rt_rq)->curr;
+	struct rq *rq = rq_of_rt_rq(rt_rq);
 	struct sched_rt_entity *rt_se;
 
-	int cpu = cpu_of(rq_of_rt_rq(rt_rq));
+	int cpu = cpu_of(rq);
 
 	rt_se = rt_rq->tg->rt_se[cpu];
 
@@ -476,7 +477,7 @@ static void sched_rt_rq_enqueue(struct rt_rq *rt_rq)
 			enqueue_rt_entity(rt_se, false);
 
 		if (rt_rq->highest_prio.curr < curr->prio)
-			resched_task(curr);
+			resched_curr(rq);
 	}
 }
 
@@ -566,7 +567,7 @@ static inline void sched_rt_rq_enqueue(struct rt_rq *rt_rq)
 		return;
 
 	enqueue_top_rt_rq(rt_rq);
-	resched_task(rq->curr);
+	resched_curr(rq);
 }
 
 static inline void sched_rt_rq_dequeue(struct rt_rq *rt_rq)
@@ -948,7 +949,7 @@ static void update_curr_rt(struct rq *rq)
 			raw_spin_lock(&rt_rq->rt_runtime_lock);
 			rt_rq->rt_time += delta_exec;
 			if (sched_rt_runtime_exceeded(rt_rq))
-				resched_task(curr);
+				resched_curr(rq);
 			raw_spin_unlock(&rt_rq->rt_runtime_lock);
 		}
 	}
@@ -1363,7 +1364,7 @@ static void check_preempt_equal_prio(struct rq *rq, struct task_struct *p)
 	 * to try and push current away:
 	 */
 	requeue_task_rt(rq, p, 1);
-	resched_task(rq->curr);
+	resched_curr(rq);
 }
 
 #endif /* CONFIG_SMP */
@@ -1374,7 +1375,7 @@ static void check_preempt_equal_prio(struct rq *rq, struct task_struct *p)
 static void check_preempt_curr_rt(struct rq *rq, struct task_struct *p, int flags)
 {
 	if (p->prio < rq->curr->prio) {
-		resched_task(rq->curr);
+		resched_curr(rq);
 		return;
 	}
 
@@ -1690,7 +1691,7 @@ static int push_rt_task(struct rq *rq)
 	 * just reschedule current.
 	 */
 	if (unlikely(next_task->prio < rq->curr->prio)) {
-		resched_task(rq->curr);
+		resched_curr(rq);
 		return 0;
 	}
 
@@ -1737,7 +1738,7 @@ static int push_rt_task(struct rq *rq)
 	activate_task(lowest_rq, next_task, 0);
 	ret = 1;
 
-	resched_task(lowest_rq->curr);
+	resched_curr(lowest_rq);
 
 	double_unlock_balance(rq, lowest_rq);
 
@@ -1936,7 +1937,7 @@ static void switched_from_rt(struct rq *rq, struct task_struct *p)
 		return;
 
 	if (pull_rt_task(rq))
-		resched_task(rq->curr);
+		resched_curr(rq);
 }
 
 void __init init_sched_rt_class(void)
@@ -1974,7 +1975,7 @@ static void switched_to_rt(struct rq *rq, struct task_struct *p)
 			check_resched = 0;
 #endif /* CONFIG_SMP */
 		if (check_resched && p->prio < rq->curr->prio)
-			resched_task(rq->curr);
+			resched_curr(rq);
 	}
 }
 
@@ -2003,11 +2004,11 @@ prio_changed_rt(struct rq *rq, struct task_struct *p, int oldprio)
 		 * Only reschedule if p is still on the same runqueue.
 		 */
 		if (p->prio > rq->rt.highest_prio.curr && rq->curr == p)
-			resched_task(p);
+			resched_curr(rq);
 #else
 		/* For UP simply resched on drop of prio */
 		if (oldprio < p->prio)
-			resched_task(p);
+			resched_curr(rq);
 #endif /* CONFIG_SMP */
 	} else {
 		/*
@@ -2016,7 +2017,7 @@ prio_changed_rt(struct rq *rq, struct task_struct *p, int oldprio)
 		 * then reschedule.
 		 */
 		if (p->prio < rq->curr->prio)
-			resched_task(rq->curr);
+			resched_curr(rq);
 	}
 }
 
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index eb85676..8283c4d 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -1196,7 +1196,7 @@ extern void init_sched_rt_class(void);
 extern void init_sched_fair_class(void);
 extern void init_sched_dl_class(void);
 
-extern void resched_task(struct task_struct *p);
+extern void resched_curr(struct rq *rq);
 extern void resched_cpu(int cpu);
 
 extern struct rt_bandwidth def_rt_bandwidth;