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Message-Id: <1415260327-30465-7-git-send-email-pang.xunlei@linaro.org>
Date: Thu, 6 Nov 2014 15:52:07 +0800
From: "pang.xunlei" <pang.xunlei@...aro.org>
To: linux-kernel@...r.kernel.org
Cc: Peter Zijlstra <peterz@...radead.org>,
Steven Rostedt <rostedt@...dmis.org>,
Juri Lelli <juri.lelli@...il.com>,
"pang.xunlei" <pang.xunlei@...aro.org>
Subject: [PATCH v4 7/7] sched/deadline: Modify cpudl_find() for more cases of electing best_cpu
When a runqueue runs out of DL tasks, it may have RT tasks or non-RT
tasks or just idle. It'd be better to push the DL task to an idle cpu
or non-RT cpu if there is any.
Add idle_cpus and freert_cpus, change free_cpus to freedl_cpus in cpudl.
Add idle_enter_dl()/idle_exit_dl() to detect idle cases.
Add rt_enter_dl()/rt_exit_dl() to detect non-RT cases.
Add a set_flag parameter to cpudl_find().
Use the same thought as that in tackling RT in the former patch.
Signed-off-by: pang.xunlei <pang.xunlei@...aro.org>
---
kernel/sched/cpudeadline.c | 76 ++++++++++++++++++++++++++++++++++++--------
kernel/sched/cpudeadline.h | 15 +++++++--
kernel/sched/deadline.c | 38 +++++++++++++++++-----
kernel/sched/idle_task.c | 2 ++
kernel/sched/rt.c | 7 ++++
kernel/sched/sched.h | 11 +++++++
6 files changed, 124 insertions(+), 25 deletions(-)
diff --git a/kernel/sched/cpudeadline.c b/kernel/sched/cpudeadline.c
index 1dd446a..cc78ebe 100644
--- a/kernel/sched/cpudeadline.c
+++ b/kernel/sched/cpudeadline.c
@@ -98,16 +98,31 @@ static inline int cpudl_maximum(struct cpudl *cp)
* @cp: the cpudl max-heap context
* @p: the task
* @later_mask: a mask to fill in with the selected CPUs (not NULL)
+ * @set_flag: a flag to determine if should set the later_mask.
*
* Returns: (int)bool - CPUs were found
*/
int cpudl_find(struct cpudl *cp, struct task_struct *p,
- struct cpumask *later_mask)
+ struct cpumask *later_mask, int set_flag)
{
const struct sched_dl_entity *dl_se = &p->dl;
cpumask_and(later_mask, cpu_active_mask, &p->cpus_allowed);
- if (cpumask_and(later_mask, later_mask, cp->free_cpus)) {
+ /* sync for idle_cpus, freert_cpus, freedl_cpus */
+ smp_rmb();
+
+ if (cpumask_any_and(later_mask, cp->idle_cpus) < nr_cpu_ids) {
+ if (set_flag)
+ cpumask_and(later_mask, &p->cpus_allowed,
+ cp->idle_cpus);
+ return 1;
+ } else if (cpumask_any_and(later_mask, cp->freert_cpus)
+ < nr_cpu_ids) {
+ if (set_flag)
+ cpumask_and(later_mask, &p->cpus_allowed,
+ cp->freert_cpus);
+ return 1;
+ } else if (cpumask_and(later_mask, later_mask, cp->freedl_cpus)) {
return 1;
} else if (cpumask_and(later_mask, cpumask_of(cpudl_maximum(cp)),
&p->cpus_allowed) &&
@@ -123,21 +138,39 @@ int cpudl_find(struct cpudl *cp, struct task_struct *p,
* @cp: the cpudl max-heap context
* @cpu: the target cpu
* @dl: the new earliest deadline for this cpu
- *
+ * @set_flags: CPUDL_SET_XXX, CPUDL_CLEAR_XXX
* Notes: assumes cpu_rq(cpu)->lock is locked
*
* Returns: (void)
*/
-void cpudl_set(struct cpudl *cp, int cpu, u64 dl, int is_valid)
+void cpudl_set(struct cpudl *cp, int cpu, u64 dl, int set_flags)
{
int old_idx, new_cpu;
unsigned long flags;
WARN_ON(!cpu_present(cpu));
+ /* We can do this percpu operation without spinlock */
+ switch (set_flags) {
+ case CPUDL_SET_IDLE:
+ cpumask_set_cpu(cpu, cp->idle_cpus);
+ return;
+ case CPUDL_CLEAR_IDLE:
+ cpumask_clear_cpu(cpu, cp->idle_cpus);
+ return;
+ case CPUDL_SET_FREERT:
+ cpumask_set_cpu(cpu, cp->freert_cpus);
+ return;
+ case CPUDL_CLEAR_FREERT:
+ cpumask_clear_cpu(cpu, cp->freert_cpus);
+ return;
+ default:
+ break;
+ }
+
raw_spin_lock_irqsave(&cp->lock, flags);
old_idx = cp->elements[cpu].idx;
- if (!is_valid) {
+ if (set_flags == CPUDL_SET_FREEDL) {
/* remove item */
if (old_idx == IDX_INVALID) {
/*
@@ -159,7 +192,7 @@ void cpudl_set(struct cpudl *cp, int cpu, u64 dl, int is_valid)
cpudl_exchange(cp, old_idx, parent(old_idx));
old_idx = parent(old_idx);
}
- cpumask_set_cpu(cpu, cp->free_cpus);
+ cpumask_set_cpu(cpu, cp->freedl_cpus);
cpudl_heapify(cp, old_idx);
goto out;
@@ -171,7 +204,7 @@ void cpudl_set(struct cpudl *cp, int cpu, u64 dl, int is_valid)
cp->elements[cp->size - 1].cpu = cpu;
cp->elements[cpu].idx = cp->size - 1;
cpudl_change_key(cp, cp->size - 1, dl);
- cpumask_clear_cpu(cpu, cp->free_cpus);
+ cpumask_clear_cpu(cpu, cp->freedl_cpus);
} else {
cpudl_change_key(cp, old_idx, dl);
}
@@ -187,7 +220,7 @@ out:
*/
void cpudl_set_freecpu(int cpu, struct cpudl *cp)
{
- cpumask_set_cpu(cpu, cp->free_cpus);
+ cpumask_set_cpu(cpu, cp->freedl_cpus);
}
/*
@@ -206,17 +239,30 @@ int cpudl_init(struct cpudl *cp)
sizeof(struct cpudl_item),
GFP_KERNEL);
if (!cp->elements)
- return -ENOMEM;
+ goto out;
- if (!zalloc_cpumask_var(&cp->free_cpus, GFP_KERNEL)) {
- kfree(cp->elements);
- return -ENOMEM;
- }
+ if (!zalloc_cpumask_var(&cp->freedl_cpus, GFP_KERNEL))
+ goto free_elements;
+
+ if (!zalloc_cpumask_var(&cp->freert_cpus, GFP_KERNEL))
+ goto free_freedl_cpus;
+
+ if (!zalloc_cpumask_var(&cp->idle_cpus, GFP_KERNEL))
+ goto free_freert_cpus;
for_each_possible_cpu(i)
cp->elements[i].idx = IDX_INVALID;
return 0;
+
+free_freert_cpus:
+ kfree(cp->freert_cpus);
+free_freedl_cpus:
+ kfree(cp->freedl_cpus);
+free_elements:
+ kfree(cp->elements);
+out:
+ return -ENOMEM;
}
/*
@@ -225,6 +271,8 @@ int cpudl_init(struct cpudl *cp)
*/
void cpudl_cleanup(struct cpudl *cp)
{
- free_cpumask_var(cp->free_cpus);
+ free_cpumask_var(cp->freedl_cpus);
+ free_cpumask_var(cp->freert_cpus);
+ free_cpumask_var(cp->idle_cpus);
kfree(cp->elements);
}
diff --git a/kernel/sched/cpudeadline.h b/kernel/sched/cpudeadline.h
index 71478fc..b2d4004 100644
--- a/kernel/sched/cpudeadline.h
+++ b/kernel/sched/cpudeadline.h
@@ -5,6 +5,13 @@
#define IDX_INVALID -1
+#define CPUDL_SET_DL 1 /* set deadline value, clear freedl_cpus */
+#define CPUDL_SET_FREEDL 2 /* set freedl_cpus */
+#define CPUDL_SET_FREERT 3 /* set freert_cpus */
+#define CPUDL_CLEAR_FREERT 4 /* clear freert_cpus */
+#define CPUDL_SET_IDLE 5 /* set idle_cpus */
+#define CPUDL_CLEAR_IDLE 6 /* clear idle_cpus */
+
struct cpudl_item {
u64 dl;
int cpu;
@@ -14,15 +21,17 @@ struct cpudl_item {
struct cpudl {
raw_spinlock_t lock;
int size;
- cpumask_var_t free_cpus;
+ cpumask_var_t idle_cpus;
+ cpumask_var_t freert_cpus;
+ cpumask_var_t freedl_cpus;
struct cpudl_item *elements;
};
#ifdef CONFIG_SMP
int cpudl_find(struct cpudl *cp, struct task_struct *p,
- struct cpumask *later_mask);
-void cpudl_set(struct cpudl *cp, int cpu, u64 dl, int is_valid);
+ struct cpumask *later_mask, int set_flag);
+void cpudl_set(struct cpudl *cp, int cpu, u64 dl, int set_flags);
int cpudl_init(struct cpudl *cp);
void cpudl_cleanup(struct cpudl *cp);
void cpudl_set_freecpu(int cpu, struct cpudl *cp);
diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
index 01d3aaab..1e9941a 100644
--- a/kernel/sched/deadline.c
+++ b/kernel/sched/deadline.c
@@ -673,6 +673,26 @@ static void update_curr_dl(struct rq *rq)
#ifdef CONFIG_SMP
+void idle_enter_dl(struct rq *this_rq)
+{
+ cpudl_set(&this_rq->rd->cpudl, this_rq->cpu, 0, CPUDL_SET_IDLE);
+}
+
+void idle_exit_dl(struct rq *this_rq)
+{
+ cpudl_set(&this_rq->rd->cpudl, this_rq->cpu, 0, CPUDL_CLEAR_IDLE);
+}
+
+void rt_enter_dl(struct rq *this_rq)
+{
+ cpudl_set(&this_rq->rd->cpudl, this_rq->cpu, 0, CPUDL_CLEAR_FREERT);
+}
+
+void rt_exit_dl(struct rq *this_rq)
+{
+ cpudl_set(&this_rq->rd->cpudl, this_rq->cpu, 0, CPUDL_SET_FREERT);
+}
+
static struct task_struct *pick_next_earliest_dl_task(struct rq *rq, int cpu);
static inline u64 next_deadline(struct rq *rq)
@@ -699,7 +719,7 @@ static void inc_dl_deadline(struct dl_rq *dl_rq, u64 deadline)
*/
dl_rq->earliest_dl.next = dl_rq->earliest_dl.curr;
dl_rq->earliest_dl.curr = deadline;
- cpudl_set(&rq->rd->cpudl, rq->cpu, deadline, 1);
+ cpudl_set(&rq->rd->cpudl, rq->cpu, deadline, CPUDL_SET_DL);
} else if (dl_rq->earliest_dl.next == 0 ||
dl_time_before(deadline, dl_rq->earliest_dl.next)) {
/*
@@ -723,7 +743,7 @@ static void dec_dl_deadline(struct dl_rq *dl_rq, u64 deadline)
if (!dl_rq->dl_nr_running) {
dl_rq->earliest_dl.curr = 0;
dl_rq->earliest_dl.next = 0;
- cpudl_set(&rq->rd->cpudl, rq->cpu, 0, 0);
+ cpudl_set(&rq->rd->cpudl, rq->cpu, 0, CPUDL_SET_FREEDL);
} else {
struct rb_node *leftmost = dl_rq->rb_leftmost;
struct sched_dl_entity *entry;
@@ -731,7 +751,8 @@ static void dec_dl_deadline(struct dl_rq *dl_rq, u64 deadline)
entry = rb_entry(leftmost, struct sched_dl_entity, rb_node);
dl_rq->earliest_dl.curr = entry->deadline;
dl_rq->earliest_dl.next = next_deadline(rq);
- cpudl_set(&rq->rd->cpudl, rq->cpu, entry->deadline, 1);
+ cpudl_set(&rq->rd->cpudl, rq->cpu,
+ entry->deadline, CPUDL_SET_DL);
}
}
@@ -976,7 +997,7 @@ static void check_preempt_equal_dl(struct rq *rq, struct task_struct *p)
* let's hope p can move out.
*/
if (rq->curr->nr_cpus_allowed == 1 ||
- !cpudl_find(&rq->rd->cpudl, rq->curr, later_mask))
+ !cpudl_find(&rq->rd->cpudl, rq->curr, later_mask, 0))
return;
/*
@@ -984,7 +1005,7 @@ static void check_preempt_equal_dl(struct rq *rq, struct task_struct *p)
* see if it is pushed or pulled somewhere else.
*/
if (p->nr_cpus_allowed != 1 &&
- cpudl_find(&rq->rd->cpudl, p, later_mask))
+ cpudl_find(&rq->rd->cpudl, p, later_mask, 0))
return;
resched_curr(rq);
@@ -1190,7 +1211,7 @@ static int find_later_rq(struct task_struct *task)
* We have to consider system topology and task affinity
* first, then we can look for a suitable cpu.
*/
- if (!cpudl_find(&task_rq(task)->rd->cpudl, task, later_mask))
+ if (!cpudl_find(&task_rq(task)->rd->cpudl, task, later_mask, 1))
return -1;
if (cpumask_weight(later_mask) == 1)
@@ -1570,7 +1591,8 @@ static void rq_online_dl(struct rq *rq)
dl_set_overload(rq);
if (rq->dl.dl_nr_running > 0)
- cpudl_set(&rq->rd->cpudl, rq->cpu, rq->dl.earliest_dl.curr, 1);
+ cpudl_set(&rq->rd->cpudl, rq->cpu,
+ rq->dl.earliest_dl.curr, CPUDL_SET_DL);
}
/* Assumes rq->lock is held */
@@ -1579,7 +1601,7 @@ static void rq_offline_dl(struct rq *rq)
if (rq->dl.overloaded)
dl_clear_overload(rq);
- cpudl_set(&rq->rd->cpudl, rq->cpu, 0, 0);
+ cpudl_set(&rq->rd->cpudl, rq->cpu, 0, CPUDL_SET_FREEDL);
}
void init_sched_dl_class(void)
diff --git a/kernel/sched/idle_task.c b/kernel/sched/idle_task.c
index e053347..7838e56 100644
--- a/kernel/sched/idle_task.c
+++ b/kernel/sched/idle_task.c
@@ -26,6 +26,7 @@ static void check_preempt_curr_idle(struct rq *rq, struct task_struct *p, int fl
static struct task_struct *
pick_next_task_idle(struct rq *rq, struct task_struct *prev)
{
+ idle_enter_dl(rq);
idle_enter_rt(rq);
put_prev_task(rq, prev);
@@ -49,6 +50,7 @@ dequeue_task_idle(struct rq *rq, struct task_struct *p, int flags)
static void put_prev_task_idle(struct rq *rq, struct task_struct *prev)
{
+ idle_exit_dl(rq);
idle_exit_rt(rq);
idle_exit_fair(rq);
rq_last_tick_reset(rq);
diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c
index 49164f1..ee49b94 100644
--- a/kernel/sched/rt.c
+++ b/kernel/sched/rt.c
@@ -1484,6 +1484,9 @@ pick_next_task_rt(struct rq *rq, struct task_struct *prev)
if (!rt_rq->rt_queued)
return NULL;
+ if (prev->sched_class != &rt_sched_class)
+ rt_enter_dl(rq);
+
put_prev_task(rq, prev);
p = _pick_next_task_rt(rq);
@@ -1498,6 +1501,10 @@ pick_next_task_rt(struct rq *rq, struct task_struct *prev)
static void put_prev_task_rt(struct rq *rq, struct task_struct *p)
{
+ /* Neglect stop preempt. As for dl preempt, doesn't matter */
+ if (rq->curr->sched_class != &rt_sched_class)
+ rt_exit_dl(rq);
+
update_curr_rt(rq);
/*
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index cc603fa..b76dfef 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -1162,6 +1162,12 @@ extern void update_group_capacity(struct sched_domain *sd, int cpu);
extern void trigger_load_balance(struct rq *rq);
+extern void rt_enter_dl(struct rq *this_rq);
+extern void rt_exit_dl(struct rq *this_rq);
+
+extern void idle_enter_dl(struct rq *this_rq);
+extern void idle_exit_dl(struct rq *this_rq);
+
extern void idle_enter_rt(struct rq *this_rq);
extern void idle_exit_rt(struct rq *this_rq);
@@ -1169,6 +1175,11 @@ extern void idle_enter_fair(struct rq *this_rq);
extern void idle_exit_fair(struct rq *this_rq);
#else
+static inline void rt_enter_dl(struct rq *rq) { }
+static inline void rt_exit_dl(struct rq *rq) { }
+
+static inline void idle_enter_dl(struct rq *rq) { }
+static inline void idle_exit_dl(struct rq *rq) { }
static inline void idle_enter_rt(struct rq *rq) { }
static inline void idle_exit_rt(struct rq *rq) { }
--
1.7.9.5
--
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