[tip:sched/core] sched: Add enqueue/dequeue flags

tip-bot for Peter Zijlstra
2010-04-02T19:14:49Z

Commit-ID: 371fd7e7a56a5c136d31aa980011bd2f131c3ef5
Gitweb: http://git.kernel.org/tip/371fd7e7a56a5c136d31aa980011bd2f131c3ef5
Author: Peter Zijlstra <a.p.zijlstra@chello.nl>
AuthorDate: Wed, 24 Mar 2010 16:38:48 +0100
Committer: Ingo Molnar <mingo@elte.hu>
CommitDate: Fri, 2 Apr 2010 20:12:05 +0200

sched: Add enqueue/dequeue flags

In order to reduce the dependency on TASK_WAKING rework the enqueue
interface to support a proper flags field.

Replace the int wakeup, bool head arguments with an int flags argument
and create the following flags:

ENQUEUE_WAKEUP - the enqueue is a wakeup of a sleeping task,
ENQUEUE_WAKING - the enqueue has relative vruntime due to
having sched_class::task_waking() called,
ENQUEUE_HEAD - the waking task should be places on the head
of the priority queue (where appropriate).

For symmetry also convert sched_class::dequeue() to a flags scheme.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
include/linux/sched.h | 11 ++++++++---
kernel/sched.c | 32 +++++++++++++++++---------------
kernel/sched_fair.c | 25 ++++++++-----------------
kernel/sched_idletask.c | 2 +-
kernel/sched_rt.c | 8 ++++----
5 files changed, 38 insertions(+), 40 deletions(-)

diff --git a/include/linux/sched.h b/include/linux/sched.h
index fb6c188..e3e900f 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1032,12 +1032,17 @@ struct sched_domain;
#define WF_SYNC 0x01 /* waker goes to sleep after wakup */
#define WF_FORK 0x02 /* child wakeup after fork */

+#define ENQUEUE_WAKEUP 1
+#define ENQUEUE_WAKING 2
+#define ENQUEUE_HEAD 4
+
+#define DEQUEUE_SLEEP 1
+
struct sched_class {
const struct sched_class *next;

- void (*enqueue_task) (struct rq *rq, struct task_struct *p, int wakeup,
- bool head);
- void (*dequeue_task) (struct rq *rq, struct task_struct *p, int sleep);
+ void (*enqueue_task) (struct rq *rq, struct task_struct *p, int flags);
+ void (*dequeue_task) (struct rq *rq, struct task_struct *p, int flags);
void (*yield_task) (struct rq *rq);

void (*check_preempt_curr) (struct rq *rq, struct task_struct *p, int flags);
diff --git a/kernel/sched.c b/kernel/sched.c
index 14c8d2a..4a57e96 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -1877,44 +1877,43 @@ static void update_avg(u64 *avg, u64 sample)
*avg += diff >> 3;
}

-static void
-enqueue_task(struct rq *rq, struct task_struct *p, int wakeup, bool head)
+static void enqueue_task(struct rq *rq, struct task_struct *p, int flags)
{
update_rq_clock(rq);
sched_info_queued(p);
- p->sched_class->enqueue_task(rq, p, wakeup, head);
+ 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 sleep)
+static void dequeue_task(struct rq *rq, struct task_struct *p, int flags)
{
update_rq_clock(rq);
sched_info_dequeued(p);
- p->sched_class->dequeue_task(rq, p, sleep);
+ p->sched_class->dequeue_task(rq, p, flags);
p->se.on_rq = 0;
}

/*
* activate_task - move a task to the runqueue.
*/
-static void activate_task(struct rq *rq, struct task_struct *p, int wakeup)
+static void activate_task(struct rq *rq, struct task_struct *p, int flags)
{
if (task_contributes_to_load(p))
rq->nr_uninterruptible--;

- enqueue_task(rq, p, wakeup, false);
+ enqueue_task(rq, p, flags);
inc_nr_running(rq);
}

/*
* deactivate_task - remove a task from the runqueue.
*/
-static void deactivate_task(struct rq *rq, struct task_struct *p, int sleep)
+static void deactivate_task(struct rq *rq, struct task_struct *p, int flags)
{
if (task_contributes_to_load(p))
rq->nr_uninterruptible++;

- dequeue_task(rq, p, sleep);
+ dequeue_task(rq, p, flags);
dec_nr_running(rq);
}

@@ -2353,6 +2352,7 @@ static int try_to_wake_up(struct task_struct *p, unsigned int state,
{
int cpu, orig_cpu, this_cpu, success = 0;
unsigned long flags;
+ unsigned long en_flags = ENQUEUE_WAKEUP;
struct rq *rq;

this_cpu = get_cpu();
@@ -2386,8 +2386,10 @@ static int try_to_wake_up(struct task_struct *p, unsigned int state,
}
p->state = TASK_WAKING;

- if (p->sched_class->task_waking)
+ if (p->sched_class->task_waking) {
p->sched_class->task_waking(rq, p);
+ en_flags |= ENQUEUE_WAKING;
+ }

cpu = select_task_rq(rq, p, SD_BALANCE_WAKE, wake_flags);
if (cpu != orig_cpu)
@@ -2432,7 +2434,7 @@ out_activate:
schedstat_inc(p, se.statistics.nr_wakeups_local);
else
schedstat_inc(p, se.statistics.nr_wakeups_remote);
- activate_task(rq, p, 1);
+ activate_task(rq, p, en_flags);
success = 1;

out_running:
@@ -3623,7 +3625,7 @@ need_resched_nonpreemptible:
if (unlikely(signal_pending_state(prev->state, prev)))
prev->state = TASK_RUNNING;
else
- deactivate_task(rq, prev, 1);
+ deactivate_task(rq, prev, DEQUEUE_SLEEP);
switch_count = &prev->nvcsw;
}

@@ -4193,7 +4195,7 @@ void rt_mutex_setprio(struct task_struct *p, int prio)
if (running)
p->sched_class->set_curr_task(rq);
if (on_rq) {
- enqueue_task(rq, p, 0, oldprio < prio);
+ enqueue_task(rq, p, oldprio < prio ? ENQUEUE_HEAD : 0);

check_class_changed(rq, p, prev_class, oldprio, running);
}
@@ -4236,7 +4238,7 @@ void set_user_nice(struct task_struct *p, long nice)
delta = p->prio - old_prio;

if (on_rq) {
- enqueue_task(rq, p, 0, false);
+ enqueue_task(rq, p, 0);
/*
* If the task increased its priority or is running and
* lowered its priority, then reschedule its CPU:
@@ -8180,7 +8182,7 @@ void sched_move_task(struct task_struct *tsk)
if (unlikely(running))
tsk->sched_class->set_curr_task(rq);
if (on_rq)
- enqueue_task(rq, tsk, 0, false);
+ enqueue_task(rq, tsk, 0);

task_rq_unlock(rq, &flags);
}
diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c
index 8a5e763..88d3053 100644
--- a/kernel/sched_fair.c
+++ b/kernel/sched_fair.c
@@ -757,9 +757,6 @@ place_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int initial)
se->vruntime = vruntime;
}

-#define ENQUEUE_WAKEUP 1
-#define ENQUEUE_MIGRATE 2
-
static void
enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
{
@@ -767,7 +764,7 @@ enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
* Update the normalized vruntime before updating min_vruntime
* through callig update_curr().
*/
- if (!(flags & ENQUEUE_WAKEUP) || (flags & ENQUEUE_MIGRATE))
+ if (!(flags & ENQUEUE_WAKEUP) || (flags & ENQUEUE_WAKING))
se->vruntime += cfs_rq->min_vruntime;

/*
@@ -803,7 +800,7 @@ static void clear_buddies(struct cfs_rq *cfs_rq, struct sched_entity *se)
}

static void
-dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int sleep)
+dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
{
/*
* Update run-time statistics of the 'current'.
@@ -811,7 +808,7 @@ dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int sleep)
update_curr(cfs_rq);

update_stats_dequeue(cfs_rq, se);
- if (sleep) {
+ if (flags & DEQUEUE_SLEEP) {
#ifdef CONFIG_SCHEDSTATS
if (entity_is_task(se)) {
struct task_struct *tsk = task_of(se);
@@ -836,7 +833,7 @@ dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int sleep)
* update can refer to the ->curr item and we need to reflect this
* movement in our normalized position.
*/
- if (!sleep)
+ if (!(flags & DEQUEUE_SLEEP))
se->vruntime -= cfs_rq->min_vruntime;
}

@@ -1045,16 +1042,10 @@ static inline void hrtick_update(struct rq *rq)
* then put the task into the rbtree:
*/
static void
-enqueue_task_fair(struct rq *rq, struct task_struct *p, int wakeup, bool head)
+enqueue_task_fair(struct rq *rq, struct task_struct *p, int flags)
{
struct cfs_rq *cfs_rq;
struct sched_entity *se = &p->se;
- int flags = 0;
-
- if (wakeup)
- flags |= ENQUEUE_WAKEUP;
- if (p->state == TASK_WAKING)
- flags |= ENQUEUE_MIGRATE;

for_each_sched_entity(se) {
if (se->on_rq)
@@ -1072,18 +1063,18 @@ enqueue_task_fair(struct rq *rq, struct task_struct *p, int wakeup, bool head)
* decreased. We remove the task from the rbtree and
* update the fair scheduling stats:
*/
-static void dequeue_task_fair(struct rq *rq, struct task_struct *p, int sleep)
+static void dequeue_task_fair(struct rq *rq, struct task_struct *p, int flags)
{
struct cfs_rq *cfs_rq;
struct sched_entity *se = &p->se;

for_each_sched_entity(se) {
cfs_rq = cfs_rq_of(se);
- dequeue_entity(cfs_rq, se, sleep);
+ dequeue_entity(cfs_rq, se, flags);
/* Don't dequeue parent if it has other entities besides us */
if (cfs_rq->load.weight)
break;
- sleep = 1;
+ flags |= DEQUEUE_SLEEP;
}

hrtick_update(rq);
diff --git a/kernel/sched_idletask.c b/kernel/sched_idletask.c
index 5af709f..bea2b8f 100644
--- a/kernel/sched_idletask.c
+++ b/kernel/sched_idletask.c
@@ -33,7 +33,7 @@ static struct task_struct *pick_next_task_idle(struct rq *rq)
* message if some code attempts to do it:
*/
static void
-dequeue_task_idle(struct rq *rq, struct task_struct *p, int sleep)
+dequeue_task_idle(struct rq *rq, struct task_struct *p, int flags)
{
raw_spin_unlock_irq(&rq->lock);
printk(KERN_ERR "bad: scheduling from the idle thread!\n");
diff --git a/kernel/sched_rt.c b/kernel/sched_rt.c
index fde895f..8afb953 100644
--- a/kernel/sched_rt.c
+++ b/kernel/sched_rt.c
@@ -888,20 +888,20 @@ static void dequeue_rt_entity(struct sched_rt_entity *rt_se)
* Adding/removing a task to/from a priority array:
*/
static void
-enqueue_task_rt(struct rq *rq, struct task_struct *p, int wakeup, bool head)
+enqueue_task_rt(struct rq *rq, struct task_struct *p, int flags)
{
struct sched_rt_entity *rt_se = &p->rt;

- if (wakeup)
+ if (flags & ENQUEUE_WAKEUP)
rt_se->timeout = 0;

- enqueue_rt_entity(rt_se, head);
+ enqueue_rt_entity(rt_se, flags & ENQUEUE_HEAD);

if (!task_current(rq, p) && p->rt.nr_cpus_allowed > 1)
enqueue_pushable_task(rq, p);
}

-static void dequeue_task_rt(struct rq *rq, struct task_struct *p, int sleep)
+static void dequeue_task_rt(struct rq *rq, struct task_struct *p, int flags)
{
struct sched_rt_entity *rt_se = &p->rt;