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sched: Provide p->on_rq

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Provide a generic p->on_rq because the p->se.on_rq semantics are
unfavourable for lockless wakeups but needed for sched_fair.

In particular, p->on_rq is only cleared when we actually dequeue the
task in schedule() and not on any random dequeue as done by things
like __migrate_task() and __sched_setscheduler().

This also allows us to remove p->se usage from !sched_fair code.

Reviewed-by: Frank Rowand <frank.rowand@am.sony.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Nick Piggin <npiggin@kernel.dk>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/20110405152728.949545047@chello.nl
This commit is contained in:
Peter Zijlstra
2011-04-05 17:23:44 +02:00
committed by Ingo Molnar
parent d7c01d27ab
commit fd2f4419b4
5 changed files with 31 additions and 28 deletions
Download Patch File Download Diff File Expand all files Collapse all files

1
include/linux/sched.h
View File

@@ -1202,6 +1202,7 @@ struct task_struct {
#ifdef CONFIG_SMP #ifdef CONFIG_SMP
int on_cpu; int on_cpu;
#endif #endif
int on_rq;
int prio, static_prio, normal_prio; int prio, static_prio, normal_prio;
unsigned int rt_priority; unsigned int rt_priority;

38
kernel/sched.c
View File

@@ -1785,7 +1785,6 @@ static void enqueue_task(struct rq *rq, struct task_struct *p, int flags)
update_rq_clock(rq); update_rq_clock(rq);
sched_info_queued(p); sched_info_queued(p);
p->sched_class->enqueue_task(rq, p, flags); p->sched_class->enqueue_task(rq, p, flags);
p->se.on_rq = 1;
} }
static void dequeue_task(struct rq *rq, struct task_struct *p, int flags) static void dequeue_task(struct rq *rq, struct task_struct *p, int flags)
@@ -1793,7 +1792,6 @@ static void dequeue_task(struct rq *rq, struct task_struct *p, int flags)
update_rq_clock(rq); update_rq_clock(rq);
sched_info_dequeued(p); sched_info_dequeued(p);
p->sched_class->dequeue_task(rq, p, flags); p->sched_class->dequeue_task(rq, p, flags);
p->se.on_rq = 0;
} }
/* /*
@@ -2128,7 +2126,7 @@ static void check_preempt_curr(struct rq *rq, struct task_struct *p, int flags)
* A queue event has occurred, and we're going to schedule. In * A queue event has occurred, and we're going to schedule. In
* this case, we can save a useless back to back clock update. * this case, we can save a useless back to back clock update.
*/ */
if (rq->curr->se.on_rq && test_tsk_need_resched(rq->curr)) if (rq->curr->on_rq && test_tsk_need_resched(rq->curr))
rq->skip_clock_update = 1; rq->skip_clock_update = 1;
} }
@@ -2203,7 +2201,7 @@ static bool migrate_task(struct task_struct *p, struct rq *rq)
* If the task is not on a runqueue (and not running), then * If the task is not on a runqueue (and not running), then
* the next wake-up will properly place the task. * the next wake-up will properly place the task.
*/ */
return p->se.on_rq || task_running(rq, p); return p->on_rq || task_running(rq, p);
} }
/* /*
@@ -2263,7 +2261,7 @@ unsigned long wait_task_inactive(struct task_struct *p, long match_state)
rq = task_rq_lock(p, &flags); rq = task_rq_lock(p, &flags);
trace_sched_wait_task(p); trace_sched_wait_task(p);
running = task_running(rq, p); running = task_running(rq, p);
on_rq = p->se.on_rq; on_rq = p->on_rq;
ncsw = 0; ncsw = 0;
if (!match_state || p->state == match_state) if (!match_state || p->state == match_state)
ncsw = p->nvcsw | LONG_MIN; /* sets MSB */ ncsw = p->nvcsw | LONG_MIN; /* sets MSB */
@@ -2444,6 +2442,7 @@ ttwu_stat(struct rq *rq, struct task_struct *p, int cpu, int wake_flags)
static void ttwu_activate(struct rq *rq, struct task_struct *p, int en_flags) static void ttwu_activate(struct rq *rq, struct task_struct *p, int en_flags)
{ {
activate_task(rq, p, en_flags); activate_task(rq, p, en_flags);
p->on_rq = 1;
/* if a worker is waking up, notify workqueue */ /* if a worker is waking up, notify workqueue */
if (p->flags & PF_WQ_WORKER) if (p->flags & PF_WQ_WORKER)
@@ -2506,7 +2505,7 @@ static int try_to_wake_up(struct task_struct *p, unsigned int state,
cpu = task_cpu(p); cpu = task_cpu(p);
if (p->se.on_rq) if (p->on_rq)
goto out_running; goto out_running;
orig_cpu = cpu; orig_cpu = cpu;
@@ -2583,7 +2582,7 @@ static void try_to_wake_up_local(struct task_struct *p)
if (!(p->state & TASK_NORMAL)) if (!(p->state & TASK_NORMAL))
return; return;
if (!p->se.on_rq) if (!p->on_rq)
ttwu_activate(rq, p, ENQUEUE_WAKEUP); ttwu_activate(rq, p, ENQUEUE_WAKEUP);
ttwu_post_activation(p, rq, 0); ttwu_post_activation(p, rq, 0);
@@ -2620,19 +2619,21 @@ int wake_up_state(struct task_struct *p, unsigned int state)
*/ */
static void __sched_fork(struct task_struct *p) static void __sched_fork(struct task_struct *p)
{ {
p->on_rq = 0;
p->se.on_rq = 0;
p->se.exec_start = 0; p->se.exec_start = 0;
p->se.sum_exec_runtime = 0; p->se.sum_exec_runtime = 0;
p->se.prev_sum_exec_runtime = 0; p->se.prev_sum_exec_runtime = 0;
p->se.nr_migrations = 0; p->se.nr_migrations = 0;
p->se.vruntime = 0; p->se.vruntime = 0;
INIT_LIST_HEAD(&p->se.group_node);
#ifdef CONFIG_SCHEDSTATS #ifdef CONFIG_SCHEDSTATS
memset(&p->se.statistics, 0, sizeof(p->se.statistics)); memset(&p->se.statistics, 0, sizeof(p->se.statistics));
#endif #endif
INIT_LIST_HEAD(&p->rt.run_list); INIT_LIST_HEAD(&p->rt.run_list);
p->se.on_rq = 0;
INIT_LIST_HEAD(&p->se.group_node);
#ifdef CONFIG_PREEMPT_NOTIFIERS #ifdef CONFIG_PREEMPT_NOTIFIERS
INIT_HLIST_HEAD(&p->preempt_notifiers); INIT_HLIST_HEAD(&p->preempt_notifiers);
@@ -2750,6 +2751,7 @@ void wake_up_new_task(struct task_struct *p, unsigned long clone_flags)
rq = task_rq_lock(p, &flags); rq = task_rq_lock(p, &flags);
activate_task(rq, p, 0); activate_task(rq, p, 0);
p->on_rq = 1;
trace_sched_wakeup_new(p, true); trace_sched_wakeup_new(p, true);
check_preempt_curr(rq, p, WF_FORK); check_preempt_curr(rq, p, WF_FORK);
#ifdef CONFIG_SMP #ifdef CONFIG_SMP
@@ -4051,7 +4053,7 @@ static inline void schedule_debug(struct task_struct *prev)
static void put_prev_task(struct rq *rq, struct task_struct *prev) static void put_prev_task(struct rq *rq, struct task_struct *prev)
{ {
if (prev->se.on_rq) if (prev->on_rq)
update_rq_clock(rq); update_rq_clock(rq);
prev->sched_class->put_prev_task(rq, prev); prev->sched_class->put_prev_task(rq, prev);
} }
@@ -4126,7 +4128,9 @@ need_resched:
if (to_wakeup) if (to_wakeup)
try_to_wake_up_local(to_wakeup); try_to_wake_up_local(to_wakeup);
} }
deactivate_task(rq, prev, DEQUEUE_SLEEP); deactivate_task(rq, prev, DEQUEUE_SLEEP);
prev->on_rq = 0;
/* /*
* If we are going to sleep and we have plugged IO queued, make * If we are going to sleep and we have plugged IO queued, make
@@ -4695,7 +4699,7 @@ void rt_mutex_setprio(struct task_struct *p, int prio)
trace_sched_pi_setprio(p, prio); trace_sched_pi_setprio(p, prio);
oldprio = p->prio; oldprio = p->prio;
prev_class = p->sched_class; prev_class = p->sched_class;
on_rq = p->se.on_rq; on_rq = p->on_rq;
running = task_current(rq, p); running = task_current(rq, p);
if (on_rq) if (on_rq)
dequeue_task(rq, p, 0); dequeue_task(rq, p, 0);
@@ -4743,7 +4747,7 @@ void set_user_nice(struct task_struct *p, long nice)
p->static_prio = NICE_TO_PRIO(nice); p->static_prio = NICE_TO_PRIO(nice);
goto out_unlock; goto out_unlock;
} }
on_rq = p->se.on_rq; on_rq = p->on_rq;
if (on_rq) if (on_rq)
dequeue_task(rq, p, 0); dequeue_task(rq, p, 0);
@@ -4877,8 +4881,6 @@ static struct task_struct *find_process_by_pid(pid_t pid)
static void static void
__setscheduler(struct rq *rq, struct task_struct *p, int policy, int prio) __setscheduler(struct rq *rq, struct task_struct *p, int policy, int prio)
{ {
BUG_ON(p->se.on_rq);
p->policy = policy; p->policy = policy;
p->rt_priority = prio; p->rt_priority = prio;
p->normal_prio = normal_prio(p); p->normal_prio = normal_prio(p);
@@ -5044,7 +5046,7 @@ recheck:
raw_spin_unlock_irqrestore(&p->pi_lock, flags); raw_spin_unlock_irqrestore(&p->pi_lock, flags);
goto recheck; goto recheck;
} }
on_rq = p->se.on_rq; on_rq = p->on_rq;
running = task_current(rq, p); running = task_current(rq, p);
if (on_rq) if (on_rq)
deactivate_task(rq, p, 0); deactivate_task(rq, p, 0);
@@ -5965,7 +5967,7 @@ static int __migrate_task(struct task_struct *p, int src_cpu, int dest_cpu)
* If we're not on a rq, the next wake-up will ensure we're * If we're not on a rq, the next wake-up will ensure we're
* placed properly. * placed properly.
*/ */
if (p->se.on_rq) { if (p->on_rq) {
deactivate_task(rq_src, p, 0); deactivate_task(rq_src, p, 0);
set_task_cpu(p, dest_cpu); set_task_cpu(p, dest_cpu);
activate_task(rq_dest, p, 0); activate_task(rq_dest, p, 0);
@@ -8339,7 +8341,7 @@ static void normalize_task(struct rq *rq, struct task_struct *p)
int old_prio = p->prio; int old_prio = p->prio;
int on_rq; int on_rq;
on_rq = p->se.on_rq; on_rq = p->on_rq;
if (on_rq) if (on_rq)
deactivate_task(rq, p, 0); deactivate_task(rq, p, 0);
__setscheduler(rq, p, SCHED_NORMAL, 0); __setscheduler(rq, p, SCHED_NORMAL, 0);
@@ -8682,7 +8684,7 @@ void sched_move_task(struct task_struct *tsk)
rq = task_rq_lock(tsk, &flags); rq = task_rq_lock(tsk, &flags);
running = task_current(rq, tsk); running = task_current(rq, tsk);
on_rq = tsk->se.on_rq; on_rq = tsk->on_rq;
if (on_rq) if (on_rq)
dequeue_task(rq, tsk, 0); dequeue_task(rq, tsk, 0);

2
kernel/sched_debug.c
View File

@@ -152,7 +152,7 @@ static void print_rq(struct seq_file *m, struct rq *rq, int rq_cpu)
read_lock_irqsave(&tasklist_lock, flags); read_lock_irqsave(&tasklist_lock, flags);
do_each_thread(g, p) { do_each_thread(g, p) {
if (!p->se.on_rq || task_cpu(p) != rq_cpu) if (!p->on_rq || task_cpu(p) != rq_cpu)
continue; continue;
print_task(m, rq, p); print_task(m, rq, p);

16
kernel/sched_rt.c
View File

@@ -1136,7 +1136,7 @@ static void put_prev_task_rt(struct rq *rq, struct task_struct *p)
* The previous task needs to be made eligible for pushing * The previous task needs to be made eligible for pushing
* if it is still active * if it is still active
*/ */
if (p->se.on_rq && p->rt.nr_cpus_allowed > 1) if (on_rt_rq(&p->rt) && p->rt.nr_cpus_allowed > 1)
enqueue_pushable_task(rq, p); enqueue_pushable_task(rq, p);
} }
@@ -1287,7 +1287,7 @@ static struct rq *find_lock_lowest_rq(struct task_struct *task, struct rq *rq)
!cpumask_test_cpu(lowest_rq->cpu, !cpumask_test_cpu(lowest_rq->cpu,
&task->cpus_allowed) || &task->cpus_allowed) ||
task_running(rq, task) || task_running(rq, task) ||
!task->se.on_rq)) { !task->on_rq)) {
raw_spin_unlock(&lowest_rq->lock); raw_spin_unlock(&lowest_rq->lock);
lowest_rq = NULL; lowest_rq = NULL;
@@ -1321,7 +1321,7 @@ static struct task_struct *pick_next_pushable_task(struct rq *rq)
BUG_ON(task_current(rq, p)); BUG_ON(task_current(rq, p));
BUG_ON(p->rt.nr_cpus_allowed <= 1); BUG_ON(p->rt.nr_cpus_allowed <= 1);
BUG_ON(!p->se.on_rq); BUG_ON(!p->on_rq);
BUG_ON(!rt_task(p)); BUG_ON(!rt_task(p));
return p; return p;
@@ -1467,7 +1467,7 @@ static int pull_rt_task(struct rq *this_rq)
*/ */
if (p && (p->prio < this_rq->rt.highest_prio.curr)) { if (p && (p->prio < this_rq->rt.highest_prio.curr)) {
WARN_ON(p == src_rq->curr); WARN_ON(p == src_rq->curr);
WARN_ON(!p->se.on_rq); WARN_ON(!p->on_rq);
/* /*
* There's a chance that p is higher in priority * There's a chance that p is higher in priority
@@ -1538,7 +1538,7 @@ static void set_cpus_allowed_rt(struct task_struct *p,
* Update the migration status of the RQ if we have an RT task * Update the migration status of the RQ if we have an RT task
* which is running AND changing its weight value. * which is running AND changing its weight value.
*/ */
if (p->se.on_rq && (weight != p->rt.nr_cpus_allowed)) { if (p->on_rq && (weight != p->rt.nr_cpus_allowed)) {
struct rq *rq = task_rq(p); struct rq *rq = task_rq(p);
if (!task_current(rq, p)) { if (!task_current(rq, p)) {
@@ -1608,7 +1608,7 @@ static void switched_from_rt(struct rq *rq, struct task_struct *p)
* we may need to handle the pulling of RT tasks * we may need to handle the pulling of RT tasks
* now. * now.
*/ */
if (p->se.on_rq && !rq->rt.rt_nr_running) if (p->on_rq && !rq->rt.rt_nr_running)
pull_rt_task(rq); pull_rt_task(rq);
} }
@@ -1638,7 +1638,7 @@ static void switched_to_rt(struct rq *rq, struct task_struct *p)
* If that current running task is also an RT task * If that current running task is also an RT task
* then see if we can move to another run queue. * then see if we can move to another run queue.
*/ */
if (p->se.on_rq && rq->curr != p) { if (p->on_rq && rq->curr != p) {
#ifdef CONFIG_SMP #ifdef CONFIG_SMP
if (rq->rt.overloaded && push_rt_task(rq) && if (rq->rt.overloaded && push_rt_task(rq) &&
/* Don't resched if we changed runqueues */ /* Don't resched if we changed runqueues */
@@ -1657,7 +1657,7 @@ static void switched_to_rt(struct rq *rq, struct task_struct *p)
static void static void
prio_changed_rt(struct rq *rq, struct task_struct *p, int oldprio) prio_changed_rt(struct rq *rq, struct task_struct *p, int oldprio)
{ {
if (!p->se.on_rq) if (!p->on_rq)
return; return;
if (rq->curr == p) { if (rq->curr == p) {

2
kernel/sched_stoptask.c
View File

@@ -26,7 +26,7 @@ static struct task_struct *pick_next_task_stop(struct rq *rq)
{ {
struct task_struct *stop = rq->stop; struct task_struct *stop = rq->stop;
if (stop && stop->se.on_rq) if (stop && stop->on_rq)
return stop; return stop;
return NULL; return NULL;