Enqueue deprioritized RT tasks to head of prio array
This patch backports Peter Z's enqueue to head of prio array on
de-prioritization to 2.6.24.7-rt14 which doesn't have the
enqueue_rt_entity and associated changes.
I've run several long running real-time java benchmarks and it's
holding so far. Steven, please consider this patch for inclusion
in the next 2.6.24.7-rtX release.
Peter, I didn't include your Signed-off-by as only about half your
original patch applied to 2.6.24.7-r14. If you're happy with this
version, would you also sign off?
Signed-off-by: Darren Hart <dvhltc@xxxxxxxxxx>
---
Index: linux-2.6.24.7-ibmrt2.6-view/include/linux/sched.h
===================================================================
--- linux-2.6.24.7-ibmrt2.6-view.orig/include/linux/sched.h
+++ linux-2.6.24.7-ibmrt2.6-view/include/linux/sched.h
@@ -897,11 +897,16 @@ struct uts_namespace;
struct rq;
struct sched_domain;
+#define ENQUEUE_WAKEUP 0x01
+#define ENQUEUE_HEAD 0x02
+
+#define DEQUEUE_SLEEP 0x01
+
struct sched_class {
const struct sched_class *next;
- void (*enqueue_task) (struct rq *rq, struct task_struct *p, int wakeup);
- 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);
int (*select_task_rq)(struct task_struct *p, int sync);
Index: linux-2.6.24.7-ibmrt2.6-view/kernel/sched.c
===================================================================
--- linux-2.6.24.7-ibmrt2.6-view.orig/kernel/sched.c
+++ linux-2.6.24.7-ibmrt2.6-view/kernel/sched.c
@@ -1046,7 +1046,7 @@ static const u32 prio_to_wmult[40] = {
/* 15 */ 119304647, 148102320, 186737708, 238609294, 286331153,
};
-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);
/*
* runqueue iterator, to support SMP load-balancing between different
@@ -1155,16 +1155,16 @@ static void set_load_weight(struct task_
p->se.load.inv_weight = prio_to_wmult[p->static_prio - MAX_RT_PRIO];
}
-static void enqueue_task(struct rq *rq, struct task_struct *p, int wakeup)
+static void enqueue_task(struct rq *rq, struct task_struct *p, int flags)
{
sched_info_queued(p);
- p->sched_class->enqueue_task(rq, p, wakeup);
+ 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)
{
- p->sched_class->dequeue_task(rq, p, sleep);
+ p->sched_class->dequeue_task(rq, p, flags);
p->se.on_rq = 0;
}
@@ -1219,26 +1219,26 @@ static int effective_prio(struct task_st
/*
* 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 (p->state == TASK_UNINTERRUPTIBLE)
rq->nr_uninterruptible--;
ftrace_event_task_activate(p, cpu_of(rq));
- enqueue_task(rq, p, wakeup);
+ enqueue_task(rq, p, flags);
inc_nr_running(p, 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 (p->state == TASK_UNINTERRUPTIBLE)
rq->nr_uninterruptible++;
ftrace_event_task_deactivate(p, cpu_of(rq));
- dequeue_task(rq, p, sleep);
+ dequeue_task(rq, p, flags);
dec_nr_running(p, rq);
}
@@ -1759,7 +1759,7 @@ out_activate:
else
schedstat_inc(p, se.nr_wakeups_remote);
update_rq_clock(rq);
- activate_task(rq, p, 1);
+ activate_task(rq, p, ENQUEUE_WAKEUP);
check_preempt_curr(rq, p);
success = 1;
@@ -3968,7 +3968,7 @@ asmlinkage void __sched __schedule(void)
prev->state = TASK_RUNNING;
} else {
touch_softlockup_watchdog();
- deactivate_task(rq, prev, 1);
+ deactivate_task(rq, prev, DEQUEUE_SLEEP);
}
switch_count = &prev->nvcsw;
}
@@ -4431,7 +4431,7 @@ EXPORT_SYMBOL(sleep_on_timeout);
void task_setprio(struct task_struct *p, int prio)
{
unsigned long flags;
- int oldprio, prev_resched, on_rq, running;
+ int oldprio, prev_resched, on_rq, running, down;
struct rq *rq;
const struct sched_class *prev_class = p->sched_class;
@@ -4472,6 +4472,7 @@ void task_setprio(struct task_struct *p,
else
p->sched_class = &fair_sched_class;
+ down = (prio > p->prio) ? ENQUEUE_HEAD : 0;
p->prio = prio;
// trace_special_pid(p->pid, __PRIO(oldprio), PRIO(p));
@@ -4480,7 +4481,7 @@ void task_setprio(struct task_struct *p,
if (running)
p->sched_class->set_curr_task(rq);
if (on_rq) {
- enqueue_task(rq, p, 0);
+ enqueue_task(rq, p, down);
check_class_changed(rq, p, prev_class, oldprio, running);
}
// trace_special(prev_resched, _need_resched(), 0);
Index: linux-2.6.24.7-ibmrt2.6-view/kernel/sched_fair.c
===================================================================
--- linux-2.6.24.7-ibmrt2.6-view.orig/kernel/sched_fair.c
+++ linux-2.6.24.7-ibmrt2.6-view/kernel/sched_fair.c
@@ -756,10 +756,11 @@ static inline struct sched_entity *paren
* increased. Here we update the fair scheduling stats and
* then put the task into the rbtree:
*/
-static void enqueue_task_fair(struct rq *rq, struct task_struct *p, int wakeup)
+static void enqueue_task_fair(struct rq *rq, struct task_struct *p, int flags)
{
struct cfs_rq *cfs_rq;
struct sched_entity *se = &p->se;
+ int wakeup = flags & ENQUEUE_WAKEUP;
for_each_sched_entity(se) {
if (se->on_rq)
@@ -775,10 +776,11 @@ static void enqueue_task_fair(struct rq
* 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;
+ int sleep = flags & DEQUEUE_SLEEP;
for_each_sched_entity(se) {
cfs_rq = cfs_rq_of(se);
Index: linux-2.6.24.7-ibmrt2.6-view/kernel/sched_idletask.c
===================================================================
--- linux-2.6.24.7-ibmrt2.6-view.orig/kernel/sched_idletask.c
+++ linux-2.6.24.7-ibmrt2.6-view/kernel/sched_idletask.c
@@ -31,7 +31,7 @@ static struct task_struct *pick_next_tas
* 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)
{
spin_unlock_irq(&rq->lock);
printk(KERN_ERR "bad: scheduling from the idle thread!\n");
Index: linux-2.6.24.7-ibmrt2.6-view/kernel/sched_rt.c
===================================================================
--- linux-2.6.24.7-ibmrt2.6-view.orig/kernel/sched_rt.c
+++ linux-2.6.24.7-ibmrt2.6-view/kernel/sched_rt.c
@@ -181,11 +181,16 @@ unsigned long rt_nr_uninterruptible_cpu(
return cpu_rq(cpu)->rt.rt_nr_uninterruptible;
}
-static void enqueue_task_rt(struct rq *rq, struct task_struct *p, int wakeup)
+static void enqueue_task_rt(struct rq *rq, struct task_struct *p, int flags)
{
struct rt_prio_array *array = &rq->rt.active;
- list_add_tail(&p->run_list, array->queue + p->prio);
+
+ if (unlikely(flags & ENQUEUE_HEAD))
+ list_add(&p->run_list, array->queue + p->prio);
+ else
+ list_add_tail(&p->run_list, array->queue + p->prio);
+
__set_bit(p->prio, array->bitmap);
inc_rt_tasks(p, rq);
@@ -196,7 +201,7 @@ static void enqueue_task_rt(struct rq *r
/*
* Adding/removing a task to/from a priority array:
*/
-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 rt_prio_array *array = &rq->rt.active;
@@ -306,7 +311,7 @@ static void put_prev_task_rt(struct rq *
#define RT_MAX_TRIES 3
static int double_lock_balance(struct rq *this_rq, struct rq *busiest);
-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);
static int pick_rt_task(struct rq *rq, struct task_struct *p, int cpu)
{
--
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