sched: Transform resched_task() into resched_curr()

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>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/r/20140628200219.1778.18735.stgit@localhost
Signed-off-by: Ingo Molnar <mingo@kernel.org>

diff --git a/Documentation/trace/ftrace.txt b/Documentation/trace/ftrace.txt
index 2479b2a..4da4261 100644 (file)
--- 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 c9c9ff7..41a1953 100644 (file)
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -2786,7 +2786,7 @@ 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();
 
@@ -2804,7 +2804,7 @@ 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();
 
@@ -2836,7 +2836,7 @@ 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 cf7695a..2f96081 100644 (file)
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -589,30 +589,31 @@ 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 = cpu_of(rq);
 
        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);
@@ -625,7 +626,7 @@ 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);
 }
 
@@ -1027,7 +1028,7 @@ 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;
                        }
                }
@@ -3073,7 +3074,7 @@ 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);
@@ -4299,7 +4300,7 @@ again:
                 * fairness.
                 */
                if (preempt && rq != p_rq)
-                       resched_task(p_rq->curr);
+                       resched_curr(p_rq);
        }
 
 out_unlock:
@@ -7106,7 +7107,7 @@ 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 fc4f98b..df0b77a 100644 (file)
--- a/kernel/sched/deadline.c
+++ b/kernel/sched/deadline.c
@@ -535,7 +535,7 @@ again:
                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 @@ retry:
        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 @@ retry:
        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 923fe32..f5f0cc9 100644 (file)
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -2923,7 +2923,7 @@ 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.
@@ -2947,7 +2947,7 @@ 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
@@ -3087,7 +3087,7 @@ 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;
        }
        /*
@@ -3278,7 +3278,7 @@ 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
@@ -3438,7 +3438,7 @@ 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,
@@ -3897,7 +3897,7 @@ 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;
                }
 
@@ -4766,7 +4766,7 @@ 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
@@ -7457,7 +7457,7 @@ 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;
@@ -7482,7 +7482,7 @@ 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);
 }
@@ -7545,7 +7545,7 @@ 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 (file)
--- 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 671a8b5..5f6edca 100644 (file)
--- 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)
@@ -951,7 +952,7 @@ 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);
                }
        }
@@ -1366,7 +1367,7 @@ 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 */
@@ -1377,7 +1378,7 @@ 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;
        }
 
@@ -1693,7 +1694,7 @@ retry:
         * just reschedule current.
         */
        if (unlikely(next_task->prio < rq->curr->prio)) {
-               resched_task(rq->curr);
+               resched_curr(rq);
                return 0;
        }
 
@@ -1740,7 +1741,7 @@ retry:
        activate_task(lowest_rq, next_task, 0);
        ret = 1;
 
-       resched_task(lowest_rq->curr);
+       resched_curr(lowest_rq);
 
        double_unlock_balance(rq, lowest_rq);
 
@@ -1939,7 +1940,7 @@ 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)
@@ -1977,7 +1978,7 @@ 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);
        }
 }
 
@@ -2006,11 +2007,11 @@ 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 {
                /*
@@ -2019,7 +2020,7 @@ 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 0191ed5..1283945 100644 (file)
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -1199,7 +1199,7 @@ 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;