Merge branch 'sched/urgent' into sched/core
Conflicts: kernel/sched.c
Necessary due to the urgent fixes which conflict with the code move
from sched.c to sched_fair.c
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
diff --git a/Documentation/feature-removal-schedule.txt b/Documentation/feature-removal-schedule.txt
index 0a46833..dbc1206 100644
--- a/Documentation/feature-removal-schedule.txt
+++ b/Documentation/feature-removal-schedule.txt
@@ -6,21 +6,6 @@
---------------------------
-What: USER_SCHED
-When: 2.6.34
-
-Why: USER_SCHED was implemented as a proof of concept for group scheduling.
- The effect of USER_SCHED can already be achieved from userspace with
- the help of libcgroup. The removal of USER_SCHED will also simplify
- the scheduler code with the removal of one major ifdef. There are also
- issues USER_SCHED has with USER_NS. A decision was taken not to fix
- those and instead remove USER_SCHED. Also new group scheduling
- features will not be implemented for USER_SCHED.
-
-Who: Dhaval Giani <dhaval@linux.vnet.ibm.com>
-
----------------------------
-
What: PRISM54
When: 2.6.34
diff --git a/include/linux/kernel.h b/include/linux/kernel.h
index 328bca6..1221d23 100644
--- a/include/linux/kernel.h
+++ b/include/linux/kernel.h
@@ -124,7 +124,7 @@
#endif
#ifdef CONFIG_DEBUG_SPINLOCK_SLEEP
- void __might_sleep(char *file, int line, int preempt_offset);
+ void __might_sleep(const char *file, int line, int preempt_offset);
/**
* might_sleep - annotation for functions that can sleep
*
@@ -138,7 +138,8 @@
# define might_sleep() \
do { __might_sleep(__FILE__, __LINE__, 0); might_resched(); } while (0)
#else
- static inline void __might_sleep(char *file, int line, int preempt_offset) { }
+ static inline void __might_sleep(const char *file, int line,
+ int preempt_offset) { }
# define might_sleep() do { might_resched(); } while (0)
#endif
diff --git a/include/linux/percpu_counter.h b/include/linux/percpu_counter.h
index a7684a5..794662b 100644
--- a/include/linux/percpu_counter.h
+++ b/include/linux/percpu_counter.h
@@ -98,9 +98,6 @@
fbc->count = amount;
}
-#define __percpu_counter_add(fbc, amount, batch) \
- percpu_counter_add(fbc, amount)
-
static inline void
percpu_counter_add(struct percpu_counter *fbc, s64 amount)
{
@@ -109,6 +106,12 @@
preempt_enable();
}
+static inline void
+__percpu_counter_add(struct percpu_counter *fbc, s64 amount, s32 batch)
+{
+ percpu_counter_add(fbc, amount);
+}
+
static inline s64 percpu_counter_read(struct percpu_counter *fbc)
{
return fbc->count;
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 1f5fa53..0eef87b5 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -740,14 +740,6 @@
uid_t uid;
struct user_namespace *user_ns;
-#ifdef CONFIG_USER_SCHED
- struct task_group *tg;
-#ifdef CONFIG_SYSFS
- struct kobject kobj;
- struct delayed_work work;
-#endif
-#endif
-
#ifdef CONFIG_PERF_EVENTS
atomic_long_t locked_vm;
#endif
@@ -1087,7 +1079,8 @@
struct sched_class {
const struct sched_class *next;
- void (*enqueue_task) (struct rq *rq, struct task_struct *p, int wakeup);
+ 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 (*yield_task) (struct rq *rq);
@@ -1099,14 +1092,6 @@
#ifdef CONFIG_SMP
int (*select_task_rq)(struct task_struct *p, int sd_flag, int flags);
- unsigned long (*load_balance) (struct rq *this_rq, int this_cpu,
- struct rq *busiest, unsigned long max_load_move,
- struct sched_domain *sd, enum cpu_idle_type idle,
- int *all_pinned, int *this_best_prio);
-
- int (*move_one_task) (struct rq *this_rq, int this_cpu,
- struct rq *busiest, struct sched_domain *sd,
- enum cpu_idle_type idle);
void (*pre_schedule) (struct rq *this_rq, struct task_struct *task);
void (*post_schedule) (struct rq *this_rq);
void (*task_waking) (struct rq *this_rq, struct task_struct *task);
@@ -2520,13 +2505,9 @@
extern void normalize_rt_tasks(void);
-#ifdef CONFIG_GROUP_SCHED
+#ifdef CONFIG_CGROUP_SCHED
extern struct task_group init_task_group;
-#ifdef CONFIG_USER_SCHED
-extern struct task_group root_task_group;
-extern void set_tg_uid(struct user_struct *user);
-#endif
extern struct task_group *sched_create_group(struct task_group *parent);
extern void sched_destroy_group(struct task_group *tg);
diff --git a/init/Kconfig b/init/Kconfig
index d95ca7c..ed9c19e 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -445,57 +445,6 @@
config HAVE_UNSTABLE_SCHED_CLOCK
bool
-config GROUP_SCHED
- bool "Group CPU scheduler"
- depends on EXPERIMENTAL
- default n
- help
- This feature lets CPU scheduler recognize task groups and control CPU
- bandwidth allocation to such task groups.
- In order to create a group from arbitrary set of processes, use
- CONFIG_CGROUPS. (See Control Group support.)
-
-config FAIR_GROUP_SCHED
- bool "Group scheduling for SCHED_OTHER"
- depends on GROUP_SCHED
- default GROUP_SCHED
-
-config RT_GROUP_SCHED
- bool "Group scheduling for SCHED_RR/FIFO"
- depends on EXPERIMENTAL
- depends on GROUP_SCHED
- default n
- help
- This feature lets you explicitly allocate real CPU bandwidth
- to users or control groups (depending on the "Basis for grouping tasks"
- setting below. If enabled, it will also make it impossible to
- schedule realtime tasks for non-root users until you allocate
- realtime bandwidth for them.
- See Documentation/scheduler/sched-rt-group.txt for more information.
-
-choice
- depends on GROUP_SCHED
- prompt "Basis for grouping tasks"
- default USER_SCHED
-
-config USER_SCHED
- bool "user id"
- help
- This option will choose userid as the basis for grouping
- tasks, thus providing equal CPU bandwidth to each user.
-
-config CGROUP_SCHED
- bool "Control groups"
- depends on CGROUPS
- help
- This option allows you to create arbitrary task groups
- using the "cgroup" pseudo filesystem and control
- the cpu bandwidth allocated to each such task group.
- Refer to Documentation/cgroups/cgroups.txt for more
- information on "cgroup" pseudo filesystem.
-
-endchoice
-
menuconfig CGROUPS
boolean "Control Group support"
help
@@ -616,6 +565,36 @@
Now, memory usage of swap_cgroup is 2 bytes per entry. If swap page
size is 4096bytes, 512k per 1Gbytes of swap.
+menuconfig CGROUP_SCHED
+ bool "Group CPU scheduler"
+ depends on EXPERIMENTAL && CGROUPS
+ default n
+ help
+ This feature lets CPU scheduler recognize task groups and control CPU
+ bandwidth allocation to such task groups. It uses cgroups to group
+ tasks.
+
+if CGROUP_SCHED
+config FAIR_GROUP_SCHED
+ bool "Group scheduling for SCHED_OTHER"
+ depends on CGROUP_SCHED
+ default CGROUP_SCHED
+
+config RT_GROUP_SCHED
+ bool "Group scheduling for SCHED_RR/FIFO"
+ depends on EXPERIMENTAL
+ depends on CGROUP_SCHED
+ default n
+ help
+ This feature lets you explicitly allocate real CPU bandwidth
+ to users or control groups (depending on the "Basis for grouping tasks"
+ setting below. If enabled, it will also make it impossible to
+ schedule realtime tasks for non-root users until you allocate
+ realtime bandwidth for them.
+ See Documentation/scheduler/sched-rt-group.txt for more information.
+
+endif #CGROUP_SCHED
+
endif # CGROUPS
config MM_OWNER
diff --git a/kernel/ksysfs.c b/kernel/ksysfs.c
index 3feaf5a..6b1ccc3 100644
--- a/kernel/ksysfs.c
+++ b/kernel/ksysfs.c
@@ -197,16 +197,8 @@
goto group_exit;
}
- /* create the /sys/kernel/uids/ directory */
- error = uids_sysfs_init();
- if (error)
- goto notes_exit;
-
return 0;
-notes_exit:
- if (notes_size > 0)
- sysfs_remove_bin_file(kernel_kobj, ¬es_attr);
group_exit:
sysfs_remove_group(kernel_kobj, &kernel_attr_group);
kset_exit:
diff --git a/kernel/kthread.c b/kernel/kthread.c
index fbb6222..82ed0ea 100644
--- a/kernel/kthread.c
+++ b/kernel/kthread.c
@@ -101,7 +101,7 @@
*
* Description: This helper function creates and names a kernel
* thread. The thread will be stopped: use wake_up_process() to start
- * it. See also kthread_run(), kthread_create_on_cpu().
+ * it. See also kthread_run().
*
* When woken, the thread will run @threadfn() with @data as its
* argument. @threadfn() can either call do_exit() directly if it is a
diff --git a/kernel/sched.c b/kernel/sched.c
index 404e201..af5fa23 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -233,7 +233,7 @@
*/
static DEFINE_MUTEX(sched_domains_mutex);
-#ifdef CONFIG_GROUP_SCHED
+#ifdef CONFIG_CGROUP_SCHED
#include <linux/cgroup.h>
@@ -243,13 +243,7 @@
/* task group related information */
struct task_group {
-#ifdef CONFIG_CGROUP_SCHED
struct cgroup_subsys_state css;
-#endif
-
-#ifdef CONFIG_USER_SCHED
- uid_t uid;
-#endif
#ifdef CONFIG_FAIR_GROUP_SCHED
/* schedulable entities of this group on each cpu */
@@ -274,35 +268,7 @@
struct list_head children;
};
-#ifdef CONFIG_USER_SCHED
-
-/* Helper function to pass uid information to create_sched_user() */
-void set_tg_uid(struct user_struct *user)
-{
- user->tg->uid = user->uid;
-}
-
-/*
- * Root task group.
- * Every UID task group (including init_task_group aka UID-0) will
- * be a child to this group.
- */
-struct task_group root_task_group;
-
-#ifdef CONFIG_FAIR_GROUP_SCHED
-/* Default task group's sched entity on each cpu */
-static DEFINE_PER_CPU(struct sched_entity, init_sched_entity);
-/* Default task group's cfs_rq on each cpu */
-static DEFINE_PER_CPU_SHARED_ALIGNED(struct cfs_rq, init_tg_cfs_rq);
-#endif /* CONFIG_FAIR_GROUP_SCHED */
-
-#ifdef CONFIG_RT_GROUP_SCHED
-static DEFINE_PER_CPU(struct sched_rt_entity, init_sched_rt_entity);
-static DEFINE_PER_CPU_SHARED_ALIGNED(struct rt_rq, init_rt_rq_var);
-#endif /* CONFIG_RT_GROUP_SCHED */
-#else /* !CONFIG_USER_SCHED */
#define root_task_group init_task_group
-#endif /* CONFIG_USER_SCHED */
/* task_group_lock serializes add/remove of task groups and also changes to
* a task group's cpu shares.
@@ -318,11 +284,7 @@
}
#endif
-#ifdef CONFIG_USER_SCHED
-# define INIT_TASK_GROUP_LOAD (2*NICE_0_LOAD)
-#else /* !CONFIG_USER_SCHED */
# define INIT_TASK_GROUP_LOAD NICE_0_LOAD
-#endif /* CONFIG_USER_SCHED */
/*
* A weight of 0 or 1 can cause arithmetics problems.
@@ -348,11 +310,7 @@
{
struct task_group *tg;
-#ifdef CONFIG_USER_SCHED
- rcu_read_lock();
- tg = __task_cred(p)->user->tg;
- rcu_read_unlock();
-#elif defined(CONFIG_CGROUP_SCHED)
+#ifdef CONFIG_CGROUP_SCHED
tg = container_of(task_subsys_state(p, cpu_cgroup_subsys_id),
struct task_group, css);
#else
@@ -383,7 +341,7 @@
return NULL;
}
-#endif /* CONFIG_GROUP_SCHED */
+#endif /* CONFIG_CGROUP_SCHED */
/* CFS-related fields in a runqueue */
struct cfs_rq {
@@ -478,7 +436,6 @@
struct rq *rq;
struct list_head leaf_rt_rq_list;
struct task_group *tg;
- struct sched_rt_entity *rt_se;
#endif
};
@@ -1409,32 +1366,6 @@
/* 15 */ 119304647, 148102320, 186737708, 238609294, 286331153,
};
-static void activate_task(struct rq *rq, struct task_struct *p, int wakeup);
-
-/*
- * runqueue iterator, to support SMP load-balancing between different
- * scheduling classes, without having to expose their internal data
- * structures to the load-balancing proper:
- */
-struct rq_iterator {
- void *arg;
- struct task_struct *(*start)(void *);
- struct task_struct *(*next)(void *);
-};
-
-#ifdef CONFIG_SMP
-static unsigned long
-balance_tasks(struct rq *this_rq, int this_cpu, struct rq *busiest,
- unsigned long max_load_move, struct sched_domain *sd,
- enum cpu_idle_type idle, int *all_pinned,
- int *this_best_prio, struct rq_iterator *iterator);
-
-static int
-iter_move_one_task(struct rq *this_rq, int this_cpu, struct rq *busiest,
- struct sched_domain *sd, enum cpu_idle_type idle,
- struct rq_iterator *iterator);
-#endif
-
/* Time spent by the tasks of the cpu accounting group executing in ... */
enum cpuacct_stat_index {
CPUACCT_STAT_USER, /* ... user mode */
@@ -1720,16 +1651,6 @@
}
}
-static void update_shares_locked(struct rq *rq, struct sched_domain *sd)
-{
- if (root_task_group_empty())
- return;
-
- raw_spin_unlock(&rq->lock);
- update_shares(sd);
- raw_spin_lock(&rq->lock);
-}
-
static void update_h_load(long cpu)
{
if (root_task_group_empty())
@@ -1744,10 +1665,6 @@
{
}
-static inline void update_shares_locked(struct rq *rq, struct sched_domain *sd)
-{
-}
-
#endif
#ifdef CONFIG_PREEMPT
@@ -1824,6 +1741,51 @@
raw_spin_unlock(&busiest->lock);
lock_set_subclass(&this_rq->lock.dep_map, 0, _RET_IP_);
}
+
+/*
+ * double_rq_lock - safely lock two runqueues
+ *
+ * Note this does not disable interrupts like task_rq_lock,
+ * you need to do so manually before calling.
+ */
+static void double_rq_lock(struct rq *rq1, struct rq *rq2)
+ __acquires(rq1->lock)
+ __acquires(rq2->lock)
+{
+ BUG_ON(!irqs_disabled());
+ if (rq1 == rq2) {
+ raw_spin_lock(&rq1->lock);
+ __acquire(rq2->lock); /* Fake it out ;) */
+ } else {
+ if (rq1 < rq2) {
+ raw_spin_lock(&rq1->lock);
+ raw_spin_lock_nested(&rq2->lock, SINGLE_DEPTH_NESTING);
+ } else {
+ raw_spin_lock(&rq2->lock);
+ raw_spin_lock_nested(&rq1->lock, SINGLE_DEPTH_NESTING);
+ }
+ }
+ update_rq_clock(rq1);
+ update_rq_clock(rq2);
+}
+
+/*
+ * double_rq_unlock - safely unlock two runqueues
+ *
+ * Note this does not restore interrupts like task_rq_unlock,
+ * you need to do so manually after calling.
+ */
+static void double_rq_unlock(struct rq *rq1, struct rq *rq2)
+ __releases(rq1->lock)
+ __releases(rq2->lock)
+{
+ raw_spin_unlock(&rq1->lock);
+ if (rq1 != rq2)
+ raw_spin_unlock(&rq2->lock);
+ else
+ __release(rq2->lock);
+}
+
#endif
#ifdef CONFIG_FAIR_GROUP_SCHED
@@ -1853,18 +1815,14 @@
#endif
}
-#include "sched_stats.h"
-#include "sched_idletask.c"
-#include "sched_fair.c"
-#include "sched_rt.c"
-#ifdef CONFIG_SCHED_DEBUG
-# include "sched_debug.c"
-#endif
+static const struct sched_class rt_sched_class;
#define sched_class_highest (&rt_sched_class)
#define for_each_class(class) \
for (class = sched_class_highest; class; class = class->next)
+#include "sched_stats.h"
+
static void inc_nr_running(struct rq *rq)
{
rq->nr_running++;
@@ -1902,13 +1860,14 @@
*avg += diff >> 3;
}
-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 wakeup, bool head)
{
if (wakeup)
p->se.start_runtime = p->se.sum_exec_runtime;
sched_info_queued(p);
- p->sched_class->enqueue_task(rq, p, wakeup);
+ p->sched_class->enqueue_task(rq, p, wakeup, head);
p->se.on_rq = 1;
}
@@ -1931,6 +1890,37 @@
}
/*
+ * activate_task - move a task to the runqueue.
+ */
+static void activate_task(struct rq *rq, struct task_struct *p, int wakeup)
+{
+ if (task_contributes_to_load(p))
+ rq->nr_uninterruptible--;
+
+ enqueue_task(rq, p, wakeup, false);
+ 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)
+{
+ if (task_contributes_to_load(p))
+ rq->nr_uninterruptible++;
+
+ dequeue_task(rq, p, sleep);
+ dec_nr_running(rq);
+}
+
+#include "sched_idletask.c"
+#include "sched_fair.c"
+#include "sched_rt.c"
+#ifdef CONFIG_SCHED_DEBUG
+# include "sched_debug.c"
+#endif
+
+/*
* __normal_prio - return the priority that is based on the static prio
*/
static inline int __normal_prio(struct task_struct *p)
@@ -1976,30 +1966,6 @@
return p->prio;
}
-/*
- * activate_task - move a task to the runqueue.
- */
-static void activate_task(struct rq *rq, struct task_struct *p, int wakeup)
-{
- if (task_contributes_to_load(p))
- rq->nr_uninterruptible--;
-
- enqueue_task(rq, p, wakeup);
- 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)
-{
- if (task_contributes_to_load(p))
- rq->nr_uninterruptible++;
-
- dequeue_task(rq, p, sleep);
- dec_nr_running(rq);
-}
-
/**
* task_curr - is this task currently executing on a CPU?
* @p: the task in question.
@@ -3137,50 +3103,6 @@
#ifdef CONFIG_SMP
/*
- * double_rq_lock - safely lock two runqueues
- *
- * Note this does not disable interrupts like task_rq_lock,
- * you need to do so manually before calling.
- */
-static void double_rq_lock(struct rq *rq1, struct rq *rq2)
- __acquires(rq1->lock)
- __acquires(rq2->lock)
-{
- BUG_ON(!irqs_disabled());
- if (rq1 == rq2) {
- raw_spin_lock(&rq1->lock);
- __acquire(rq2->lock); /* Fake it out ;) */
- } else {
- if (rq1 < rq2) {
- raw_spin_lock(&rq1->lock);
- raw_spin_lock_nested(&rq2->lock, SINGLE_DEPTH_NESTING);
- } else {
- raw_spin_lock(&rq2->lock);
- raw_spin_lock_nested(&rq1->lock, SINGLE_DEPTH_NESTING);
- }
- }
- update_rq_clock(rq1);
- update_rq_clock(rq2);
-}
-
-/*
- * double_rq_unlock - safely unlock two runqueues
- *
- * Note this does not restore interrupts like task_rq_unlock,
- * you need to do so manually after calling.
- */
-static void double_rq_unlock(struct rq *rq1, struct rq *rq2)
- __releases(rq1->lock)
- __releases(rq2->lock)
-{
- raw_spin_unlock(&rq1->lock);
- if (rq1 != rq2)
- raw_spin_unlock(&rq2->lock);
- else
- __release(rq2->lock);
-}
-
-/*
* sched_exec - execve() is a valuable balancing opportunity, because at
* this point the task has the smallest effective memory and cache footprint.
*/
@@ -3228,1782 +3150,6 @@
task_rq_unlock(rq, &flags);
}
-/*
- * pull_task - move a task from a remote runqueue to the local runqueue.
- * Both runqueues must be locked.
- */
-static void pull_task(struct rq *src_rq, struct task_struct *p,
- struct rq *this_rq, int this_cpu)
-{
- deactivate_task(src_rq, p, 0);
- set_task_cpu(p, this_cpu);
- activate_task(this_rq, p, 0);
- check_preempt_curr(this_rq, p, 0);
-}
-
-/*
- * can_migrate_task - may task p from runqueue rq be migrated to this_cpu?
- */
-static
-int can_migrate_task(struct task_struct *p, struct rq *rq, int this_cpu,
- struct sched_domain *sd, enum cpu_idle_type idle,
- int *all_pinned)
-{
- int tsk_cache_hot = 0;
- /*
- * We do not migrate tasks that are:
- * 1) running (obviously), or
- * 2) cannot be migrated to this CPU due to cpus_allowed, or
- * 3) are cache-hot on their current CPU.
- */
- if (!cpumask_test_cpu(this_cpu, &p->cpus_allowed)) {
- schedstat_inc(p, se.nr_failed_migrations_affine);
- return 0;
- }
- *all_pinned = 0;
-
- if (task_running(rq, p)) {
- schedstat_inc(p, se.nr_failed_migrations_running);
- return 0;
- }
-
- /*
- * Aggressive migration if:
- * 1) task is cache cold, or
- * 2) too many balance attempts have failed.
- */
-
- tsk_cache_hot = task_hot(p, rq->clock, sd);
- if (!tsk_cache_hot ||
- sd->nr_balance_failed > sd->cache_nice_tries) {
-#ifdef CONFIG_SCHEDSTATS
- if (tsk_cache_hot) {
- schedstat_inc(sd, lb_hot_gained[idle]);
- schedstat_inc(p, se.nr_forced_migrations);
- }
-#endif
- return 1;
- }
-
- if (tsk_cache_hot) {
- schedstat_inc(p, se.nr_failed_migrations_hot);
- return 0;
- }
- return 1;
-}
-
-static unsigned long
-balance_tasks(struct rq *this_rq, int this_cpu, struct rq *busiest,
- unsigned long max_load_move, struct sched_domain *sd,
- enum cpu_idle_type idle, int *all_pinned,
- int *this_best_prio, struct rq_iterator *iterator)
-{
- int loops = 0, pulled = 0, pinned = 0;
- struct task_struct *p;
- long rem_load_move = max_load_move;
-
- if (max_load_move == 0)
- goto out;
-
- pinned = 1;
-
- /*
- * Start the load-balancing iterator:
- */
- p = iterator->start(iterator->arg);
-next:
- if (!p || loops++ > sysctl_sched_nr_migrate)
- goto out;
-
- if ((p->se.load.weight >> 1) > rem_load_move ||
- !can_migrate_task(p, busiest, this_cpu, sd, idle, &pinned)) {
- p = iterator->next(iterator->arg);
- goto next;
- }
-
- pull_task(busiest, p, this_rq, this_cpu);
- pulled++;
- rem_load_move -= p->se.load.weight;
-
-#ifdef CONFIG_PREEMPT
- /*
- * NEWIDLE balancing is a source of latency, so preemptible kernels
- * will stop after the first task is pulled to minimize the critical
- * section.
- */
- if (idle == CPU_NEWLY_IDLE)
- goto out;
-#endif
-
- /*
- * We only want to steal up to the prescribed amount of weighted load.
- */
- if (rem_load_move > 0) {
- if (p->prio < *this_best_prio)
- *this_best_prio = p->prio;
- p = iterator->next(iterator->arg);
- goto next;
- }
-out:
- /*
- * Right now, this is one of only two places pull_task() is called,
- * so we can safely collect pull_task() stats here rather than
- * inside pull_task().
- */
- schedstat_add(sd, lb_gained[idle], pulled);
-
- if (all_pinned)
- *all_pinned = pinned;
-
- return max_load_move - rem_load_move;
-}
-
-/*
- * move_tasks tries to move up to max_load_move weighted load from busiest to
- * this_rq, as part of a balancing operation within domain "sd".
- * Returns 1 if successful and 0 otherwise.
- *
- * Called with both runqueues locked.
- */
-static int move_tasks(struct rq *this_rq, int this_cpu, struct rq *busiest,
- unsigned long max_load_move,
- struct sched_domain *sd, enum cpu_idle_type idle,
- int *all_pinned)
-{
- const struct sched_class *class = sched_class_highest;
- unsigned long total_load_moved = 0;
- int this_best_prio = this_rq->curr->prio;
-
- do {
- total_load_moved +=
- class->load_balance(this_rq, this_cpu, busiest,
- max_load_move - total_load_moved,
- sd, idle, all_pinned, &this_best_prio);
- class = class->next;
-
-#ifdef CONFIG_PREEMPT
- /*
- * NEWIDLE balancing is a source of latency, so preemptible
- * kernels will stop after the first task is pulled to minimize
- * the critical section.
- */
- if (idle == CPU_NEWLY_IDLE && this_rq->nr_running)
- break;
-#endif
- } while (class && max_load_move > total_load_moved);
-
- return total_load_moved > 0;
-}
-
-static int
-iter_move_one_task(struct rq *this_rq, int this_cpu, struct rq *busiest,
- struct sched_domain *sd, enum cpu_idle_type idle,
- struct rq_iterator *iterator)
-{
- struct task_struct *p = iterator->start(iterator->arg);
- int pinned = 0;
-
- while (p) {
- if (can_migrate_task(p, busiest, this_cpu, sd, idle, &pinned)) {
- pull_task(busiest, p, this_rq, this_cpu);
- /*
- * Right now, this is only the second place pull_task()
- * is called, so we can safely collect pull_task()
- * stats here rather than inside pull_task().
- */
- schedstat_inc(sd, lb_gained[idle]);
-
- return 1;
- }
- p = iterator->next(iterator->arg);
- }
-
- return 0;
-}
-
-/*
- * move_one_task tries to move exactly one task from busiest to this_rq, as
- * part of active balancing operations within "domain".
- * Returns 1 if successful and 0 otherwise.
- *
- * Called with both runqueues locked.
- */
-static int move_one_task(struct rq *this_rq, int this_cpu, struct rq *busiest,
- struct sched_domain *sd, enum cpu_idle_type idle)
-{
- const struct sched_class *class;
-
- for_each_class(class) {
- if (class->move_one_task(this_rq, this_cpu, busiest, sd, idle))
- return 1;
- }
-
- return 0;
-}
-/********** Helpers for find_busiest_group ************************/
-/*
- * sd_lb_stats - Structure to store the statistics of a sched_domain
- * during load balancing.
- */
-struct sd_lb_stats {
- struct sched_group *busiest; /* Busiest group in this sd */
- struct sched_group *this; /* Local group in this sd */
- unsigned long total_load; /* Total load of all groups in sd */
- unsigned long total_pwr; /* Total power of all groups in sd */
- unsigned long avg_load; /* Average load across all groups in sd */
-
- /** Statistics of this group */
- unsigned long this_load;
- unsigned long this_load_per_task;
- unsigned long this_nr_running;
-
- /* Statistics of the busiest group */
- unsigned long max_load;
- unsigned long busiest_load_per_task;
- unsigned long busiest_nr_running;
-
- int group_imb; /* Is there imbalance in this sd */
-#if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
- int power_savings_balance; /* Is powersave balance needed for this sd */
- struct sched_group *group_min; /* Least loaded group in sd */
- struct sched_group *group_leader; /* Group which relieves group_min */
- unsigned long min_load_per_task; /* load_per_task in group_min */
- unsigned long leader_nr_running; /* Nr running of group_leader */
- unsigned long min_nr_running; /* Nr running of group_min */
-#endif
-};
-
-/*
- * sg_lb_stats - stats of a sched_group required for load_balancing
- */
-struct sg_lb_stats {
- unsigned long avg_load; /*Avg load across the CPUs of the group */
- unsigned long group_load; /* Total load over the CPUs of the group */
- unsigned long sum_nr_running; /* Nr tasks running in the group */
- unsigned long sum_weighted_load; /* Weighted load of group's tasks */
- unsigned long group_capacity;
- int group_imb; /* Is there an imbalance in the group ? */
-};
-
-/**
- * group_first_cpu - Returns the first cpu in the cpumask of a sched_group.
- * @group: The group whose first cpu is to be returned.
- */
-static inline unsigned int group_first_cpu(struct sched_group *group)
-{
- return cpumask_first(sched_group_cpus(group));
-}
-
-/**
- * get_sd_load_idx - Obtain the load index for a given sched domain.
- * @sd: The sched_domain whose load_idx is to be obtained.
- * @idle: The Idle status of the CPU for whose sd load_icx is obtained.
- */
-static inline int get_sd_load_idx(struct sched_domain *sd,
- enum cpu_idle_type idle)
-{
- int load_idx;
-
- switch (idle) {
- case CPU_NOT_IDLE:
- load_idx = sd->busy_idx;
- break;
-
- case CPU_NEWLY_IDLE:
- load_idx = sd->newidle_idx;
- break;
- default:
- load_idx = sd->idle_idx;
- break;
- }
-
- return load_idx;
-}
-
-
-#if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
-/**
- * init_sd_power_savings_stats - Initialize power savings statistics for
- * the given sched_domain, during load balancing.
- *
- * @sd: Sched domain whose power-savings statistics are to be initialized.
- * @sds: Variable containing the statistics for sd.
- * @idle: Idle status of the CPU at which we're performing load-balancing.
- */
-static inline void init_sd_power_savings_stats(struct sched_domain *sd,
- struct sd_lb_stats *sds, enum cpu_idle_type idle)
-{
- /*
- * Busy processors will not participate in power savings
- * balance.
- */
- if (idle == CPU_NOT_IDLE || !(sd->flags & SD_POWERSAVINGS_BALANCE))
- sds->power_savings_balance = 0;
- else {
- sds->power_savings_balance = 1;
- sds->min_nr_running = ULONG_MAX;
- sds->leader_nr_running = 0;
- }
-}
-
-/**
- * update_sd_power_savings_stats - Update the power saving stats for a
- * sched_domain while performing load balancing.
- *
- * @group: sched_group belonging to the sched_domain under consideration.
- * @sds: Variable containing the statistics of the sched_domain
- * @local_group: Does group contain the CPU for which we're performing
- * load balancing ?
- * @sgs: Variable containing the statistics of the group.
- */
-static inline void update_sd_power_savings_stats(struct sched_group *group,
- struct sd_lb_stats *sds, int local_group, struct sg_lb_stats *sgs)
-{
-
- if (!sds->power_savings_balance)
- return;
-
- /*
- * If the local group is idle or completely loaded
- * no need to do power savings balance at this domain
- */
- if (local_group && (sds->this_nr_running >= sgs->group_capacity ||
- !sds->this_nr_running))
- sds->power_savings_balance = 0;
-
- /*
- * If a group is already running at full capacity or idle,
- * don't include that group in power savings calculations
- */
- if (!sds->power_savings_balance ||
- sgs->sum_nr_running >= sgs->group_capacity ||
- !sgs->sum_nr_running)
- return;
-
- /*
- * Calculate the group which has the least non-idle load.
- * This is the group from where we need to pick up the load
- * for saving power
- */
- if ((sgs->sum_nr_running < sds->min_nr_running) ||
- (sgs->sum_nr_running == sds->min_nr_running &&
- group_first_cpu(group) > group_first_cpu(sds->group_min))) {
- sds->group_min = group;
- sds->min_nr_running = sgs->sum_nr_running;
- sds->min_load_per_task = sgs->sum_weighted_load /
- sgs->sum_nr_running;
- }
-
- /*
- * Calculate the group which is almost near its
- * capacity but still has some space to pick up some load
- * from other group and save more power
- */
- if (sgs->sum_nr_running + 1 > sgs->group_capacity)
- return;
-
- if (sgs->sum_nr_running > sds->leader_nr_running ||
- (sgs->sum_nr_running == sds->leader_nr_running &&
- group_first_cpu(group) < group_first_cpu(sds->group_leader))) {
- sds->group_leader = group;
- sds->leader_nr_running = sgs->sum_nr_running;
- }
-}
-
-/**
- * check_power_save_busiest_group - see if there is potential for some power-savings balance
- * @sds: Variable containing the statistics of the sched_domain
- * under consideration.
- * @this_cpu: Cpu at which we're currently performing load-balancing.
- * @imbalance: Variable to store the imbalance.
- *
- * Description:
- * Check if we have potential to perform some power-savings balance.
- * If yes, set the busiest group to be the least loaded group in the
- * sched_domain, so that it's CPUs can be put to idle.
- *
- * Returns 1 if there is potential to perform power-savings balance.
- * Else returns 0.
- */
-static inline int check_power_save_busiest_group(struct sd_lb_stats *sds,
- int this_cpu, unsigned long *imbalance)
-{
- if (!sds->power_savings_balance)
- return 0;
-
- if (sds->this != sds->group_leader ||
- sds->group_leader == sds->group_min)
- return 0;
-
- *imbalance = sds->min_load_per_task;
- sds->busiest = sds->group_min;
-
- return 1;
-
-}
-#else /* CONFIG_SCHED_MC || CONFIG_SCHED_SMT */
-static inline void init_sd_power_savings_stats(struct sched_domain *sd,
- struct sd_lb_stats *sds, enum cpu_idle_type idle)
-{
- return;
-}
-
-static inline void update_sd_power_savings_stats(struct sched_group *group,
- struct sd_lb_stats *sds, int local_group, struct sg_lb_stats *sgs)
-{
- return;
-}
-
-static inline int check_power_save_busiest_group(struct sd_lb_stats *sds,
- int this_cpu, unsigned long *imbalance)
-{
- return 0;
-}
-#endif /* CONFIG_SCHED_MC || CONFIG_SCHED_SMT */
-
-
-unsigned long default_scale_freq_power(struct sched_domain *sd, int cpu)
-{
- return SCHED_LOAD_SCALE;
-}
-
-unsigned long __weak arch_scale_freq_power(struct sched_domain *sd, int cpu)
-{
- return default_scale_freq_power(sd, cpu);
-}
-
-unsigned long default_scale_smt_power(struct sched_domain *sd, int cpu)
-{
- unsigned long weight = cpumask_weight(sched_domain_span(sd));
- unsigned long smt_gain = sd->smt_gain;
-
- smt_gain /= weight;
-
- return smt_gain;
-}
-
-unsigned long __weak arch_scale_smt_power(struct sched_domain *sd, int cpu)
-{
- return default_scale_smt_power(sd, cpu);
-}
-
-unsigned long scale_rt_power(int cpu)
-{
- struct rq *rq = cpu_rq(cpu);
- u64 total, available;
-
- sched_avg_update(rq);
-
- total = sched_avg_period() + (rq->clock - rq->age_stamp);
- available = total - rq->rt_avg;
-
- if (unlikely((s64)total < SCHED_LOAD_SCALE))
- total = SCHED_LOAD_SCALE;
-
- total >>= SCHED_LOAD_SHIFT;
-
- return div_u64(available, total);
-}
-
-static void update_cpu_power(struct sched_domain *sd, int cpu)
-{
- unsigned long weight = cpumask_weight(sched_domain_span(sd));
- unsigned long power = SCHED_LOAD_SCALE;
- struct sched_group *sdg = sd->groups;
-
- if (sched_feat(ARCH_POWER))
- power *= arch_scale_freq_power(sd, cpu);
- else
- power *= default_scale_freq_power(sd, cpu);
-
- power >>= SCHED_LOAD_SHIFT;
-
- if ((sd->flags & SD_SHARE_CPUPOWER) && weight > 1) {
- if (sched_feat(ARCH_POWER))
- power *= arch_scale_smt_power(sd, cpu);
- else
- power *= default_scale_smt_power(sd, cpu);
-
- power >>= SCHED_LOAD_SHIFT;
- }
-
- power *= scale_rt_power(cpu);
- power >>= SCHED_LOAD_SHIFT;
-
- if (!power)
- power = 1;
-
- sdg->cpu_power = power;
-}
-
-static void update_group_power(struct sched_domain *sd, int cpu)
-{
- struct sched_domain *child = sd->child;
- struct sched_group *group, *sdg = sd->groups;
- unsigned long power;
-
- if (!child) {
- update_cpu_power(sd, cpu);
- return;
- }
-
- power = 0;
-
- group = child->groups;
- do {
- power += group->cpu_power;
- group = group->next;
- } while (group != child->groups);
-
- sdg->cpu_power = power;
-}
-
-/**
- * update_sg_lb_stats - Update sched_group's statistics for load balancing.
- * @sd: The sched_domain whose statistics are to be updated.
- * @group: sched_group whose statistics are to be updated.
- * @this_cpu: Cpu for which load balance is currently performed.
- * @idle: Idle status of this_cpu
- * @load_idx: Load index of sched_domain of this_cpu for load calc.
- * @sd_idle: Idle status of the sched_domain containing group.
- * @local_group: Does group contain this_cpu.
- * @cpus: Set of cpus considered for load balancing.
- * @balance: Should we balance.
- * @sgs: variable to hold the statistics for this group.
- */
-static inline void update_sg_lb_stats(struct sched_domain *sd,
- struct sched_group *group, int this_cpu,
- enum cpu_idle_type idle, int load_idx, int *sd_idle,
- int local_group, const struct cpumask *cpus,
- int *balance, struct sg_lb_stats *sgs)
-{
- unsigned long load, max_cpu_load, min_cpu_load;
- int i;
- unsigned int balance_cpu = -1, first_idle_cpu = 0;
- unsigned long sum_avg_load_per_task;
- unsigned long avg_load_per_task;
-
- if (local_group) {
- balance_cpu = group_first_cpu(group);
- if (balance_cpu == this_cpu)
- update_group_power(sd, this_cpu);
- }
-
- /* Tally up the load of all CPUs in the group */
- sum_avg_load_per_task = avg_load_per_task = 0;
- max_cpu_load = 0;
- min_cpu_load = ~0UL;
-
- for_each_cpu_and(i, sched_group_cpus(group), cpus) {
- struct rq *rq = cpu_rq(i);
-
- if (*sd_idle && rq->nr_running)
- *sd_idle = 0;
-
- /* Bias balancing toward cpus of our domain */
- if (local_group) {
- if (idle_cpu(i) && !first_idle_cpu) {
- first_idle_cpu = 1;
- balance_cpu = i;
- }
-
- load = target_load(i, load_idx);
- } else {
- load = source_load(i, load_idx);
- if (load > max_cpu_load)
- max_cpu_load = load;
- if (min_cpu_load > load)
- min_cpu_load = load;
- }
-
- sgs->group_load += load;
- sgs->sum_nr_running += rq->nr_running;
- sgs->sum_weighted_load += weighted_cpuload(i);
-
- sum_avg_load_per_task += cpu_avg_load_per_task(i);
- }
-
- /*
- * First idle cpu or the first cpu(busiest) in this sched group
- * is eligible for doing load balancing at this and above
- * domains. In the newly idle case, we will allow all the cpu's
- * to do the newly idle load balance.
- */
- if (idle != CPU_NEWLY_IDLE && local_group &&
- balance_cpu != this_cpu && balance) {
- *balance = 0;
- return;
- }
-
- /* Adjust by relative CPU power of the group */
- sgs->avg_load = (sgs->group_load * SCHED_LOAD_SCALE) / group->cpu_power;
-
-
- /*
- * Consider the group unbalanced when the imbalance is larger
- * than the average weight of two tasks.
- *
- * APZ: with cgroup the avg task weight can vary wildly and
- * might not be a suitable number - should we keep a
- * normalized nr_running number somewhere that negates
- * the hierarchy?
- */
- avg_load_per_task = (sum_avg_load_per_task * SCHED_LOAD_SCALE) /
- group->cpu_power;
-
- if ((max_cpu_load - min_cpu_load) > 2*avg_load_per_task)
- sgs->group_imb = 1;
-
- sgs->group_capacity =
- DIV_ROUND_CLOSEST(group->cpu_power, SCHED_LOAD_SCALE);
-}
-
-/**
- * update_sd_lb_stats - Update sched_group's statistics for load balancing.
- * @sd: sched_domain whose statistics are to be updated.
- * @this_cpu: Cpu for which load balance is currently performed.
- * @idle: Idle status of this_cpu
- * @sd_idle: Idle status of the sched_domain containing group.
- * @cpus: Set of cpus considered for load balancing.
- * @balance: Should we balance.
- * @sds: variable to hold the statistics for this sched_domain.
- */
-static inline void update_sd_lb_stats(struct sched_domain *sd, int this_cpu,
- enum cpu_idle_type idle, int *sd_idle,
- const struct cpumask *cpus, int *balance,
- struct sd_lb_stats *sds)
-{
- struct sched_domain *child = sd->child;
- struct sched_group *group = sd->groups;
- struct sg_lb_stats sgs;
- int load_idx, prefer_sibling = 0;
-
- if (child && child->flags & SD_PREFER_SIBLING)
- prefer_sibling = 1;
-
- init_sd_power_savings_stats(sd, sds, idle);
- load_idx = get_sd_load_idx(sd, idle);
-
- do {
- int local_group;
-
- local_group = cpumask_test_cpu(this_cpu,
- sched_group_cpus(group));
- memset(&sgs, 0, sizeof(sgs));
- update_sg_lb_stats(sd, group, this_cpu, idle, load_idx, sd_idle,
- local_group, cpus, balance, &sgs);
-
- if (local_group && balance && !(*balance))
- return;
-
- sds->total_load += sgs.group_load;
- sds->total_pwr += group->cpu_power;
-
- /*
- * In case the child domain prefers tasks go to siblings
- * first, lower the group capacity to one so that we'll try
- * and move all the excess tasks away.
- */
- if (prefer_sibling)
- sgs.group_capacity = min(sgs.group_capacity, 1UL);
-
- if (local_group) {
- sds->this_load = sgs.avg_load;
- sds->this = group;
- sds->this_nr_running = sgs.sum_nr_running;
- sds->this_load_per_task = sgs.sum_weighted_load;
- } else if (sgs.avg_load > sds->max_load &&
- (sgs.sum_nr_running > sgs.group_capacity ||
- sgs.group_imb)) {
- sds->max_load = sgs.avg_load;
- sds->busiest = group;
- sds->busiest_nr_running = sgs.sum_nr_running;
- sds->busiest_load_per_task = sgs.sum_weighted_load;
- sds->group_imb = sgs.group_imb;
- }
-
- update_sd_power_savings_stats(group, sds, local_group, &sgs);
- group = group->next;
- } while (group != sd->groups);
-}
-
-/**
- * fix_small_imbalance - Calculate the minor imbalance that exists
- * amongst the groups of a sched_domain, during
- * load balancing.
- * @sds: Statistics of the sched_domain whose imbalance is to be calculated.
- * @this_cpu: The cpu at whose sched_domain we're performing load-balance.
- * @imbalance: Variable to store the imbalance.
- */
-static inline void fix_small_imbalance(struct sd_lb_stats *sds,
- int this_cpu, unsigned long *imbalance)
-{
- unsigned long tmp, pwr_now = 0, pwr_move = 0;
- unsigned int imbn = 2;
-
- if (sds->this_nr_running) {
- sds->this_load_per_task /= sds->this_nr_running;
- if (sds->busiest_load_per_task >
- sds->this_load_per_task)
- imbn = 1;
- } else
- sds->this_load_per_task =
- cpu_avg_load_per_task(this_cpu);
-
- if (sds->max_load - sds->this_load + sds->busiest_load_per_task >=
- sds->busiest_load_per_task * imbn) {
- *imbalance = sds->busiest_load_per_task;
- return;
- }
-
- /*
- * OK, we don't have enough imbalance to justify moving tasks,
- * however we may be able to increase total CPU power used by
- * moving them.
- */
-
- pwr_now += sds->busiest->cpu_power *
- min(sds->busiest_load_per_task, sds->max_load);
- pwr_now += sds->this->cpu_power *
- min(sds->this_load_per_task, sds->this_load);
- pwr_now /= SCHED_LOAD_SCALE;
-
- /* Amount of load we'd subtract */
- tmp = (sds->busiest_load_per_task * SCHED_LOAD_SCALE) /
- sds->busiest->cpu_power;
- if (sds->max_load > tmp)
- pwr_move += sds->busiest->cpu_power *
- min(sds->busiest_load_per_task, sds->max_load - tmp);
-
- /* Amount of load we'd add */
- if (sds->max_load * sds->busiest->cpu_power <
- sds->busiest_load_per_task * SCHED_LOAD_SCALE)
- tmp = (sds->max_load * sds->busiest->cpu_power) /
- sds->this->cpu_power;
- else
- tmp = (sds->busiest_load_per_task * SCHED_LOAD_SCALE) /
- sds->this->cpu_power;
- pwr_move += sds->this->cpu_power *
- min(sds->this_load_per_task, sds->this_load + tmp);
- pwr_move /= SCHED_LOAD_SCALE;
-
- /* Move if we gain throughput */
- if (pwr_move > pwr_now)
- *imbalance = sds->busiest_load_per_task;
-}
-
-/**
- * calculate_imbalance - Calculate the amount of imbalance present within the
- * groups of a given sched_domain during load balance.
- * @sds: statistics of the sched_domain whose imbalance is to be calculated.
- * @this_cpu: Cpu for which currently load balance is being performed.
- * @imbalance: The variable to store the imbalance.
- */
-static inline void calculate_imbalance(struct sd_lb_stats *sds, int this_cpu,
- unsigned long *imbalance)
-{
- unsigned long max_pull;
- /*
- * In the presence of smp nice balancing, certain scenarios can have
- * max load less than avg load(as we skip the groups at or below
- * its cpu_power, while calculating max_load..)
- */
- if (sds->max_load < sds->avg_load) {
- *imbalance = 0;
- return fix_small_imbalance(sds, this_cpu, imbalance);
- }
-
- /* Don't want to pull so many tasks that a group would go idle */
- max_pull = min(sds->max_load - sds->avg_load,
- sds->max_load - sds->busiest_load_per_task);
-
- /* How much load to actually move to equalise the imbalance */
- *imbalance = min(max_pull * sds->busiest->cpu_power,
- (sds->avg_load - sds->this_load) * sds->this->cpu_power)
- / SCHED_LOAD_SCALE;
-
- /*
- * if *imbalance is less than the average load per runnable task
- * there is no gaurantee that any tasks will be moved so we'll have
- * a think about bumping its value to force at least one task to be
- * moved
- */
- if (*imbalance < sds->busiest_load_per_task)
- return fix_small_imbalance(sds, this_cpu, imbalance);
-
-}
-/******* find_busiest_group() helpers end here *********************/
-
-/**
- * find_busiest_group - Returns the busiest group within the sched_domain
- * if there is an imbalance. If there isn't an imbalance, and
- * the user has opted for power-savings, it returns a group whose
- * CPUs can be put to idle by rebalancing those tasks elsewhere, if
- * such a group exists.
- *
- * Also calculates the amount of weighted load which should be moved
- * to restore balance.
- *
- * @sd: The sched_domain whose busiest group is to be returned.
- * @this_cpu: The cpu for which load balancing is currently being performed.
- * @imbalance: Variable which stores amount of weighted load which should
- * be moved to restore balance/put a group to idle.
- * @idle: The idle status of this_cpu.
- * @sd_idle: The idleness of sd
- * @cpus: The set of CPUs under consideration for load-balancing.
- * @balance: Pointer to a variable indicating if this_cpu
- * is the appropriate cpu to perform load balancing at this_level.
- *
- * Returns: - the busiest group if imbalance exists.
- * - If no imbalance and user has opted for power-savings balance,
- * return the least loaded group whose CPUs can be
- * put to idle by rebalancing its tasks onto our group.
- */
-static struct sched_group *
-find_busiest_group(struct sched_domain *sd, int this_cpu,
- unsigned long *imbalance, enum cpu_idle_type idle,
- int *sd_idle, const struct cpumask *cpus, int *balance)
-{
- struct sd_lb_stats sds;
-
- memset(&sds, 0, sizeof(sds));
-
- /*
- * Compute the various statistics relavent for load balancing at
- * this level.
- */
- update_sd_lb_stats(sd, this_cpu, idle, sd_idle, cpus,
- balance, &sds);
-
- /* Cases where imbalance does not exist from POV of this_cpu */
- /* 1) this_cpu is not the appropriate cpu to perform load balancing
- * at this level.
- * 2) There is no busy sibling group to pull from.
- * 3) This group is the busiest group.
- * 4) This group is more busy than the avg busieness at this
- * sched_domain.
- * 5) The imbalance is within the specified limit.
- * 6) Any rebalance would lead to ping-pong
- */
- if (balance && !(*balance))
- goto ret;
-
- if (!sds.busiest || sds.busiest_nr_running == 0)
- goto out_balanced;
-
- if (sds.this_load >= sds.max_load)
- goto out_balanced;
-
- sds.avg_load = (SCHED_LOAD_SCALE * sds.total_load) / sds.total_pwr;
-
- if (sds.this_load >= sds.avg_load)
- goto out_balanced;
-
- if (100 * sds.max_load <= sd->imbalance_pct * sds.this_load)
- goto out_balanced;
-
- sds.busiest_load_per_task /= sds.busiest_nr_running;
- if (sds.group_imb)
- sds.busiest_load_per_task =
- min(sds.busiest_load_per_task, sds.avg_load);
-
- /*
- * We're trying to get all the cpus to the average_load, so we don't
- * want to push ourselves above the average load, nor do we wish to
- * reduce the max loaded cpu below the average load, as either of these
- * actions would just result in more rebalancing later, and ping-pong
- * tasks around. Thus we look for the minimum possible imbalance.
- * Negative imbalances (*we* are more loaded than anyone else) will
- * be counted as no imbalance for these purposes -- we can't fix that
- * by pulling tasks to us. Be careful of negative numbers as they'll
- * appear as very large values with unsigned longs.
- */
- if (sds.max_load <= sds.busiest_load_per_task)
- goto out_balanced;
-
- /* Looks like there is an imbalance. Compute it */
- calculate_imbalance(&sds, this_cpu, imbalance);
- return sds.busiest;
-
-out_balanced:
- /*
- * There is no obvious imbalance. But check if we can do some balancing
- * to save power.
- */
- if (check_power_save_busiest_group(&sds, this_cpu, imbalance))
- return sds.busiest;
-ret:
- *imbalance = 0;
- return NULL;
-}
-
-/*
- * find_busiest_queue - find the busiest runqueue among the cpus in group.
- */
-static struct rq *
-find_busiest_queue(struct sched_group *group, enum cpu_idle_type idle,
- unsigned long imbalance, const struct cpumask *cpus)
-{
- struct rq *busiest = NULL, *rq;
- unsigned long max_load = 0;
- int i;
-
- for_each_cpu(i, sched_group_cpus(group)) {
- unsigned long power = power_of(i);
- unsigned long capacity = DIV_ROUND_CLOSEST(power, SCHED_LOAD_SCALE);
- unsigned long wl;
-
- if (!cpumask_test_cpu(i, cpus))
- continue;
-
- rq = cpu_rq(i);
- wl = weighted_cpuload(i);
-
- /*
- * When comparing with imbalance, use weighted_cpuload()
- * which is not scaled with the cpu power.
- */
- if (capacity && rq->nr_running == 1 && wl > imbalance)
- continue;
-
- /*
- * For the load comparisons with the other cpu's, consider
- * the weighted_cpuload() scaled with the cpu power, so that
- * the load can be moved away from the cpu that is potentially
- * running at a lower capacity.
- */
- wl = (wl * SCHED_LOAD_SCALE) / power;
-
- if (wl > max_load) {
- max_load = wl;
- busiest = rq;
- }
- }
-
- return busiest;
-}
-
-/*
- * Max backoff if we encounter pinned tasks. Pretty arbitrary value, but
- * so long as it is large enough.
- */
-#define MAX_PINNED_INTERVAL 512
-
-/* Working cpumask for load_balance and load_balance_newidle. */
-static DEFINE_PER_CPU(cpumask_var_t, load_balance_tmpmask);
-
-/*
- * Check this_cpu to ensure it is balanced within domain. Attempt to move
- * tasks if there is an imbalance.
- */
-static int load_balance(int this_cpu, struct rq *this_rq,
- struct sched_domain *sd, enum cpu_idle_type idle,
- int *balance)
-{
- int ld_moved, all_pinned = 0, active_balance = 0, sd_idle = 0;
- struct sched_group *group;
- unsigned long imbalance;
- struct rq *busiest;
- unsigned long flags;
- struct cpumask *cpus = __get_cpu_var(load_balance_tmpmask);
-
- cpumask_copy(cpus, cpu_active_mask);
-
- /*
- * When power savings policy is enabled for the parent domain, idle
- * sibling can pick up load irrespective of busy siblings. In this case,
- * let the state of idle sibling percolate up as CPU_IDLE, instead of
- * portraying it as CPU_NOT_IDLE.
- */
- if (idle != CPU_NOT_IDLE && sd->flags & SD_SHARE_CPUPOWER &&
- !test_sd_parent(sd, SD_POWERSAVINGS_BALANCE))
- sd_idle = 1;
-
- schedstat_inc(sd, lb_count[idle]);
-
-redo:
- update_shares(sd);
- group = find_busiest_group(sd, this_cpu, &imbalance, idle, &sd_idle,
- cpus, balance);
-
- if (*balance == 0)
- goto out_balanced;
-
- if (!group) {
- schedstat_inc(sd, lb_nobusyg[idle]);
- goto out_balanced;
- }
-
- busiest = find_busiest_queue(group, idle, imbalance, cpus);
- if (!busiest) {
- schedstat_inc(sd, lb_nobusyq[idle]);
- goto out_balanced;
- }
-
- BUG_ON(busiest == this_rq);
-
- schedstat_add(sd, lb_imbalance[idle], imbalance);
-
- ld_moved = 0;
- if (busiest->nr_running > 1) {
- /*
- * Attempt to move tasks. If find_busiest_group has found
- * an imbalance but busiest->nr_running <= 1, the group is
- * still unbalanced. ld_moved simply stays zero, so it is
- * correctly treated as an imbalance.
- */
- local_irq_save(flags);
- double_rq_lock(this_rq, busiest);
- ld_moved = move_tasks(this_rq, this_cpu, busiest,
- imbalance, sd, idle, &all_pinned);
- double_rq_unlock(this_rq, busiest);
- local_irq_restore(flags);
-
- /*
- * some other cpu did the load balance for us.
- */
- if (ld_moved && this_cpu != smp_processor_id())
- resched_cpu(this_cpu);
-
- /* All tasks on this runqueue were pinned by CPU affinity */
- if (unlikely(all_pinned)) {
- cpumask_clear_cpu(cpu_of(busiest), cpus);
- if (!cpumask_empty(cpus))
- goto redo;
- goto out_balanced;
- }
- }
-
- if (!ld_moved) {
- schedstat_inc(sd, lb_failed[idle]);
- sd->nr_balance_failed++;
-
- if (unlikely(sd->nr_balance_failed > sd->cache_nice_tries+2)) {
-
- raw_spin_lock_irqsave(&busiest->lock, flags);
-
- /* don't kick the migration_thread, if the curr
- * task on busiest cpu can't be moved to this_cpu
- */
- if (!cpumask_test_cpu(this_cpu,
- &busiest->curr->cpus_allowed)) {
- raw_spin_unlock_irqrestore(&busiest->lock,
- flags);
- all_pinned = 1;
- goto out_one_pinned;
- }
-
- if (!busiest->active_balance) {
- busiest->active_balance = 1;
- busiest->push_cpu = this_cpu;
- active_balance = 1;
- }
- raw_spin_unlock_irqrestore(&busiest->lock, flags);
- if (active_balance)
- wake_up_process(busiest->migration_thread);
-
- /*
- * We've kicked active balancing, reset the failure
- * counter.
- */
- sd->nr_balance_failed = sd->cache_nice_tries+1;
- }
- } else
- sd->nr_balance_failed = 0;
-
- if (likely(!active_balance)) {
- /* We were unbalanced, so reset the balancing interval */
- sd->balance_interval = sd->min_interval;
- } else {
- /*
- * If we've begun active balancing, start to back off. This
- * case may not be covered by the all_pinned logic if there
- * is only 1 task on the busy runqueue (because we don't call
- * move_tasks).
- */
- if (sd->balance_interval < sd->max_interval)
- sd->balance_interval *= 2;
- }
-
- if (!ld_moved && !sd_idle && sd->flags & SD_SHARE_CPUPOWER &&
- !test_sd_parent(sd, SD_POWERSAVINGS_BALANCE))
- ld_moved = -1;
-
- goto out;
-
-out_balanced:
- schedstat_inc(sd, lb_balanced[idle]);
-
- sd->nr_balance_failed = 0;
-
-out_one_pinned:
- /* tune up the balancing interval */
- if ((all_pinned && sd->balance_interval < MAX_PINNED_INTERVAL) ||
- (sd->balance_interval < sd->max_interval))
- sd->balance_interval *= 2;
-
- if (!sd_idle && sd->flags & SD_SHARE_CPUPOWER &&
- !test_sd_parent(sd, SD_POWERSAVINGS_BALANCE))
- ld_moved = -1;
- else
- ld_moved = 0;
-out:
- if (ld_moved)
- update_shares(sd);
- return ld_moved;
-}
-
-/*
- * Check this_cpu to ensure it is balanced within domain. Attempt to move
- * tasks if there is an imbalance.
- *
- * Called from schedule when this_rq is about to become idle (CPU_NEWLY_IDLE).
- * this_rq is locked.
- */
-static int
-load_balance_newidle(int this_cpu, struct rq *this_rq, struct sched_domain *sd)
-{
- struct sched_group *group;
- struct rq *busiest = NULL;
- unsigned long imbalance;
- int ld_moved = 0;
- int sd_idle = 0;
- int all_pinned = 0;
- struct cpumask *cpus = __get_cpu_var(load_balance_tmpmask);
-
- cpumask_copy(cpus, cpu_active_mask);
-
- /*
- * When power savings policy is enabled for the parent domain, idle
- * sibling can pick up load irrespective of busy siblings. In this case,
- * let the state of idle sibling percolate up as IDLE, instead of
- * portraying it as CPU_NOT_IDLE.
- */
- if (sd->flags & SD_SHARE_CPUPOWER &&
- !test_sd_parent(sd, SD_POWERSAVINGS_BALANCE))
- sd_idle = 1;
-
- schedstat_inc(sd, lb_count[CPU_NEWLY_IDLE]);
-redo:
- update_shares_locked(this_rq, sd);
- group = find_busiest_group(sd, this_cpu, &imbalance, CPU_NEWLY_IDLE,
- &sd_idle, cpus, NULL);
- if (!group) {
- schedstat_inc(sd, lb_nobusyg[CPU_NEWLY_IDLE]);
- goto out_balanced;
- }
-
- busiest = find_busiest_queue(group, CPU_NEWLY_IDLE, imbalance, cpus);
- if (!busiest) {
- schedstat_inc(sd, lb_nobusyq[CPU_NEWLY_IDLE]);
- goto out_balanced;
- }
-
- BUG_ON(busiest == this_rq);
-
- schedstat_add(sd, lb_imbalance[CPU_NEWLY_IDLE], imbalance);
-
- ld_moved = 0;
- if (busiest->nr_running > 1) {
- /* Attempt to move tasks */
- double_lock_balance(this_rq, busiest);
- /* this_rq->clock is already updated */
- update_rq_clock(busiest);
- ld_moved = move_tasks(this_rq, this_cpu, busiest,
- imbalance, sd, CPU_NEWLY_IDLE,
- &all_pinned);
- double_unlock_balance(this_rq, busiest);
-
- if (unlikely(all_pinned)) {
- cpumask_clear_cpu(cpu_of(busiest), cpus);
- if (!cpumask_empty(cpus))
- goto redo;
- }
- }
-
- if (!ld_moved) {
- int active_balance = 0;
-
- schedstat_inc(sd, lb_failed[CPU_NEWLY_IDLE]);
- if (!sd_idle && sd->flags & SD_SHARE_CPUPOWER &&
- !test_sd_parent(sd, SD_POWERSAVINGS_BALANCE))
- return -1;
-
- if (sched_mc_power_savings < POWERSAVINGS_BALANCE_WAKEUP)
- return -1;
-
- if (sd->nr_balance_failed++ < 2)
- return -1;
-
- /*
- * The only task running in a non-idle cpu can be moved to this
- * cpu in an attempt to completely freeup the other CPU
- * package. The same method used to move task in load_balance()
- * have been extended for load_balance_newidle() to speedup
- * consolidation at sched_mc=POWERSAVINGS_BALANCE_WAKEUP (2)
- *
- * The package power saving logic comes from
- * find_busiest_group(). If there are no imbalance, then
- * f_b_g() will return NULL. However when sched_mc={1,2} then
- * f_b_g() will select a group from which a running task may be
- * pulled to this cpu in order to make the other package idle.
- * If there is no opportunity to make a package idle and if
- * there are no imbalance, then f_b_g() will return NULL and no
- * action will be taken in load_balance_newidle().
- *
- * Under normal task pull operation due to imbalance, there
- * will be more than one task in the source run queue and
- * move_tasks() will succeed. ld_moved will be true and this
- * active balance code will not be triggered.
- */
-
- /* Lock busiest in correct order while this_rq is held */
- double_lock_balance(this_rq, busiest);
-
- /*
- * don't kick the migration_thread, if the curr
- * task on busiest cpu can't be moved to this_cpu
- */
- if (!cpumask_test_cpu(this_cpu, &busiest->curr->cpus_allowed)) {
- double_unlock_balance(this_rq, busiest);
- all_pinned = 1;
- return ld_moved;
- }
-
- if (!busiest->active_balance) {
- busiest->active_balance = 1;
- busiest->push_cpu = this_cpu;
- active_balance = 1;
- }
-
- double_unlock_balance(this_rq, busiest);
- /*
- * Should not call ttwu while holding a rq->lock
- */
- raw_spin_unlock(&this_rq->lock);
- if (active_balance)
- wake_up_process(busiest->migration_thread);
- raw_spin_lock(&this_rq->lock);
-
- } else
- sd->nr_balance_failed = 0;
-
- update_shares_locked(this_rq, sd);
- return ld_moved;
-
-out_balanced:
- schedstat_inc(sd, lb_balanced[CPU_NEWLY_IDLE]);
- if (!sd_idle && sd->flags & SD_SHARE_CPUPOWER &&
- !test_sd_parent(sd, SD_POWERSAVINGS_BALANCE))
- return -1;
- sd->nr_balance_failed = 0;
-
- return 0;
-}
-
-/*
- * idle_balance is called by schedule() if this_cpu is about to become
- * idle. Attempts to pull tasks from other CPUs.
- */
-static void idle_balance(int this_cpu, struct rq *this_rq)
-{
- struct sched_domain *sd;
- int pulled_task = 0;
- unsigned long next_balance = jiffies + HZ;
-
- this_rq->idle_stamp = this_rq->clock;
-
- if (this_rq->avg_idle < sysctl_sched_migration_cost)
- return;
-
- for_each_domain(this_cpu, sd) {
- unsigned long interval;
-
- if (!(sd->flags & SD_LOAD_BALANCE))
- continue;
-
- if (sd->flags & SD_BALANCE_NEWIDLE)
- /* If we've pulled tasks over stop searching: */
- pulled_task = load_balance_newidle(this_cpu, this_rq,
- sd);
-
- interval = msecs_to_jiffies(sd->balance_interval);
- if (time_after(next_balance, sd->last_balance + interval))
- next_balance = sd->last_balance + interval;
- if (pulled_task) {
- this_rq->idle_stamp = 0;
- break;
- }
- }
- if (pulled_task || time_after(jiffies, this_rq->next_balance)) {
- /*
- * We are going idle. next_balance may be set based on
- * a busy processor. So reset next_balance.
- */
- this_rq->next_balance = next_balance;
- }
-}
-
-/*
- * active_load_balance is run by migration threads. It pushes running tasks
- * off the busiest CPU onto idle CPUs. It requires at least 1 task to be
- * running on each physical CPU where possible, and avoids physical /
- * logical imbalances.
- *
- * Called with busiest_rq locked.
- */
-static void active_load_balance(struct rq *busiest_rq, int busiest_cpu)
-{
- int target_cpu = busiest_rq->push_cpu;
- struct sched_domain *sd;
- struct rq *target_rq;
-
- /* Is there any task to move? */
- if (busiest_rq->nr_running <= 1)
- return;
-
- target_rq = cpu_rq(target_cpu);
-
- /*
- * This condition is "impossible", if it occurs
- * we need to fix it. Originally reported by
- * Bjorn Helgaas on a 128-cpu setup.
- */
- BUG_ON(busiest_rq == target_rq);
-
- /* move a task from busiest_rq to target_rq */
- double_lock_balance(busiest_rq, target_rq);
- update_rq_clock(busiest_rq);
- update_rq_clock(target_rq);
-
- /* Search for an sd spanning us and the target CPU. */
- for_each_domain(target_cpu, sd) {
- if ((sd->flags & SD_LOAD_BALANCE) &&
- cpumask_test_cpu(busiest_cpu, sched_domain_span(sd)))
- break;
- }
-
- if (likely(sd)) {
- schedstat_inc(sd, alb_count);
-
- if (move_one_task(target_rq, target_cpu, busiest_rq,
- sd, CPU_IDLE))
- schedstat_inc(sd, alb_pushed);
- else
- schedstat_inc(sd, alb_failed);
- }
- double_unlock_balance(busiest_rq, target_rq);
-}
-
-#ifdef CONFIG_NO_HZ
-static struct {
- atomic_t load_balancer;
- cpumask_var_t cpu_mask;
- cpumask_var_t ilb_grp_nohz_mask;
-} nohz ____cacheline_aligned = {
- .load_balancer = ATOMIC_INIT(-1),
-};
-
-int get_nohz_load_balancer(void)
-{
- return atomic_read(&nohz.load_balancer);
-}
-
-#if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
-/**
- * lowest_flag_domain - Return lowest sched_domain containing flag.
- * @cpu: The cpu whose lowest level of sched domain is to
- * be returned.
- * @flag: The flag to check for the lowest sched_domain
- * for the given cpu.
- *
- * Returns the lowest sched_domain of a cpu which contains the given flag.
- */
-static inline struct sched_domain *lowest_flag_domain(int cpu, int flag)
-{
- struct sched_domain *sd;
-
- for_each_domain(cpu, sd)
- if (sd && (sd->flags & flag))
- break;
-
- return sd;
-}
-
-/**
- * for_each_flag_domain - Iterates over sched_domains containing the flag.
- * @cpu: The cpu whose domains we're iterating over.
- * @sd: variable holding the value of the power_savings_sd
- * for cpu.
- * @flag: The flag to filter the sched_domains to be iterated.
- *
- * Iterates over all the scheduler domains for a given cpu that has the 'flag'
- * set, starting from the lowest sched_domain to the highest.
- */
-#define for_each_flag_domain(cpu, sd, flag) \
- for (sd = lowest_flag_domain(cpu, flag); \
- (sd && (sd->flags & flag)); sd = sd->parent)
-
-/**
- * is_semi_idle_group - Checks if the given sched_group is semi-idle.
- * @ilb_group: group to be checked for semi-idleness
- *
- * Returns: 1 if the group is semi-idle. 0 otherwise.
- *
- * We define a sched_group to be semi idle if it has atleast one idle-CPU
- * and atleast one non-idle CPU. This helper function checks if the given
- * sched_group is semi-idle or not.
- */
-static inline int is_semi_idle_group(struct sched_group *ilb_group)
-{
- cpumask_and(nohz.ilb_grp_nohz_mask, nohz.cpu_mask,
- sched_group_cpus(ilb_group));
-
- /*
- * A sched_group is semi-idle when it has atleast one busy cpu
- * and atleast one idle cpu.
- */
- if (cpumask_empty(nohz.ilb_grp_nohz_mask))
- return 0;
-
- if (cpumask_equal(nohz.ilb_grp_nohz_mask, sched_group_cpus(ilb_group)))
- return 0;
-
- return 1;
-}
-/**
- * find_new_ilb - Finds the optimum idle load balancer for nomination.
- * @cpu: The cpu which is nominating a new idle_load_balancer.
- *
- * Returns: Returns the id of the idle load balancer if it exists,
- * Else, returns >= nr_cpu_ids.
- *
- * This algorithm picks the idle load balancer such that it belongs to a
- * semi-idle powersavings sched_domain. The idea is to try and avoid
- * completely idle packages/cores just for the purpose of idle load balancing
- * when there are other idle cpu's which are better suited for that job.
- */
-static int find_new_ilb(int cpu)
-{
- struct sched_domain *sd;
- struct sched_group *ilb_group;
-
- /*
- * Have idle load balancer selection from semi-idle packages only
- * when power-aware load balancing is enabled
- */
- if (!(sched_smt_power_savings || sched_mc_power_savings))
- goto out_done;
-
- /*
- * Optimize for the case when we have no idle CPUs or only one
- * idle CPU. Don't walk the sched_domain hierarchy in such cases
- */
- if (cpumask_weight(nohz.cpu_mask) < 2)
- goto out_done;
-
- for_each_flag_domain(cpu, sd, SD_POWERSAVINGS_BALANCE) {
- ilb_group = sd->groups;
-
- do {
- if (is_semi_idle_group(ilb_group))
- return cpumask_first(nohz.ilb_grp_nohz_mask);
-
- ilb_group = ilb_group->next;
-
- } while (ilb_group != sd->groups);
- }
-
-out_done:
- return cpumask_first(nohz.cpu_mask);
-}
-#else /* (CONFIG_SCHED_MC || CONFIG_SCHED_SMT) */
-static inline int find_new_ilb(int call_cpu)
-{
- return cpumask_first(nohz.cpu_mask);
-}
-#endif
-
-/*
- * This routine will try to nominate the ilb (idle load balancing)
- * owner among the cpus whose ticks are stopped. ilb owner will do the idle
- * load balancing on behalf of all those cpus. If all the cpus in the system
- * go into this tickless mode, then there will be no ilb owner (as there is
- * no need for one) and all the cpus will sleep till the next wakeup event
- * arrives...
- *
- * For the ilb owner, tick is not stopped. And this tick will be used
- * for idle load balancing. ilb owner will still be part of
- * nohz.cpu_mask..
- *
- * While stopping the tick, this cpu will become the ilb owner if there
- * is no other owner. And will be the owner till that cpu becomes busy
- * or if all cpus in the system stop their ticks at which point
- * there is no need for ilb owner.
- *
- * When the ilb owner becomes busy, it nominates another owner, during the
- * next busy scheduler_tick()
- */
-int select_nohz_load_balancer(int stop_tick)
-{
- int cpu = smp_processor_id();
-
- if (stop_tick) {
- cpu_rq(cpu)->in_nohz_recently = 1;
-
- if (!cpu_active(cpu)) {
- if (atomic_read(&nohz.load_balancer) != cpu)
- return 0;
-
- /*
- * If we are going offline and still the leader,
- * give up!
- */
- if (atomic_cmpxchg(&nohz.load_balancer, cpu, -1) != cpu)
- BUG();
-
- return 0;
- }
-
- cpumask_set_cpu(cpu, nohz.cpu_mask);
-
- /* time for ilb owner also to sleep */
- if (cpumask_weight(nohz.cpu_mask) == num_active_cpus()) {
- if (atomic_read(&nohz.load_balancer) == cpu)
- atomic_set(&nohz.load_balancer, -1);
- return 0;
- }
-
- if (atomic_read(&nohz.load_balancer) == -1) {
- /* make me the ilb owner */
- if (atomic_cmpxchg(&nohz.load_balancer, -1, cpu) == -1)
- return 1;
- } else if (atomic_read(&nohz.load_balancer) == cpu) {
- int new_ilb;
-
- if (!(sched_smt_power_savings ||
- sched_mc_power_savings))
- return 1;
- /*
- * Check to see if there is a more power-efficient
- * ilb.
- */
- new_ilb = find_new_ilb(cpu);
- if (new_ilb < nr_cpu_ids && new_ilb != cpu) {
- atomic_set(&nohz.load_balancer, -1);
- resched_cpu(new_ilb);
- return 0;
- }
- return 1;
- }
- } else {
- if (!cpumask_test_cpu(cpu, nohz.cpu_mask))
- return 0;
-
- cpumask_clear_cpu(cpu, nohz.cpu_mask);
-
- if (atomic_read(&nohz.load_balancer) == cpu)
- if (atomic_cmpxchg(&nohz.load_balancer, cpu, -1) != cpu)
- BUG();
- }
- return 0;
-}
-#endif
-
-static DEFINE_SPINLOCK(balancing);
-
-/*
- * It checks each scheduling domain to see if it is due to be balanced,
- * and initiates a balancing operation if so.
- *
- * Balancing parameters are set up in arch_init_sched_domains.
- */
-static void rebalance_domains(int cpu, enum cpu_idle_type idle)
-{
- int balance = 1;
- struct rq *rq = cpu_rq(cpu);
- unsigned long interval;
- struct sched_domain *sd;
- /* Earliest time when we have to do rebalance again */
- unsigned long next_balance = jiffies + 60*HZ;
- int update_next_balance = 0;
- int need_serialize;
-
- for_each_domain(cpu, sd) {
- if (!(sd->flags & SD_LOAD_BALANCE))
- continue;
-
- interval = sd->balance_interval;
- if (idle != CPU_IDLE)
- interval *= sd->busy_factor;
-
- /* scale ms to jiffies */
- interval = msecs_to_jiffies(interval);
- if (unlikely(!interval))
- interval = 1;
- if (interval > HZ*NR_CPUS/10)
- interval = HZ*NR_CPUS/10;
-
- need_serialize = sd->flags & SD_SERIALIZE;
-
- if (need_serialize) {
- if (!spin_trylock(&balancing))
- goto out;
- }
-
- if (time_after_eq(jiffies, sd->last_balance + interval)) {
- if (load_balance(cpu, rq, sd, idle, &balance)) {
- /*
- * We've pulled tasks over so either we're no
- * longer idle, or one of our SMT siblings is
- * not idle.
- */
- idle = CPU_NOT_IDLE;
- }
- sd->last_balance = jiffies;
- }
- if (need_serialize)
- spin_unlock(&balancing);
-out:
- if (time_after(next_balance, sd->last_balance + interval)) {
- next_balance = sd->last_balance + interval;
- update_next_balance = 1;
- }
-
- /*
- * Stop the load balance at this level. There is another
- * CPU in our sched group which is doing load balancing more
- * actively.
- */
- if (!balance)
- break;
- }
-
- /*
- * next_balance will be updated only when there is a need.
- * When the cpu is attached to null domain for ex, it will not be
- * updated.
- */
- if (likely(update_next_balance))
- rq->next_balance = next_balance;
-}
-
-/*
- * run_rebalance_domains is triggered when needed from the scheduler tick.
- * In CONFIG_NO_HZ case, the idle load balance owner will do the
- * rebalancing for all the cpus for whom scheduler ticks are stopped.
- */
-static void run_rebalance_domains(struct softirq_action *h)
-{
- int this_cpu = smp_processor_id();
- struct rq *this_rq = cpu_rq(this_cpu);
- enum cpu_idle_type idle = this_rq->idle_at_tick ?
- CPU_IDLE : CPU_NOT_IDLE;
-
- rebalance_domains(this_cpu, idle);
-
-#ifdef CONFIG_NO_HZ
- /*
- * If this cpu is the owner for idle load balancing, then do the
- * balancing on behalf of the other idle cpus whose ticks are
- * stopped.
- */
- if (this_rq->idle_at_tick &&
- atomic_read(&nohz.load_balancer) == this_cpu) {
- struct rq *rq;
- int balance_cpu;
-
- for_each_cpu(balance_cpu, nohz.cpu_mask) {
- if (balance_cpu == this_cpu)
- continue;
-
- /*
- * If this cpu gets work to do, stop the load balancing
- * work being done for other cpus. Next load
- * balancing owner will pick it up.
- */
- if (need_resched())
- break;
-
- rebalance_domains(balance_cpu, CPU_IDLE);
-
- rq = cpu_rq(balance_cpu);
- if (time_after(this_rq->next_balance, rq->next_balance))
- this_rq->next_balance = rq->next_balance;
- }
- }
-#endif
-}
-
-static inline int on_null_domain(int cpu)
-{
- return !rcu_dereference(cpu_rq(cpu)->sd);
-}
-
-/*
- * Trigger the SCHED_SOFTIRQ if it is time to do periodic load balancing.
- *
- * In case of CONFIG_NO_HZ, this is the place where we nominate a new
- * idle load balancing owner or decide to stop the periodic load balancing,
- * if the whole system is idle.
- */
-static inline void trigger_load_balance(struct rq *rq, int cpu)
-{
-#ifdef CONFIG_NO_HZ
- /*
- * If we were in the nohz mode recently and busy at the current
- * scheduler tick, then check if we need to nominate new idle
- * load balancer.
- */
- if (rq->in_nohz_recently && !rq->idle_at_tick) {
- rq->in_nohz_recently = 0;
-
- if (atomic_read(&nohz.load_balancer) == cpu) {
- cpumask_clear_cpu(cpu, nohz.cpu_mask);
- atomic_set(&nohz.load_balancer, -1);
- }
-
- if (atomic_read(&nohz.load_balancer) == -1) {
- int ilb = find_new_ilb(cpu);
-
- if (ilb < nr_cpu_ids)
- resched_cpu(ilb);
- }
- }
-
- /*
- * If this cpu is idle and doing idle load balancing for all the
- * cpus with ticks stopped, is it time for that to stop?
- */
- if (rq->idle_at_tick && atomic_read(&nohz.load_balancer) == cpu &&
- cpumask_weight(nohz.cpu_mask) == num_online_cpus()) {
- resched_cpu(cpu);
- return;
- }
-
- /*
- * If this cpu is idle and the idle load balancing is done by
- * someone else, then no need raise the SCHED_SOFTIRQ
- */
- if (rq->idle_at_tick && atomic_read(&nohz.load_balancer) != cpu &&
- cpumask_test_cpu(cpu, nohz.cpu_mask))
- return;
-#endif
- /* Don't need to rebalance while attached to NULL domain */
- if (time_after_eq(jiffies, rq->next_balance) &&
- likely(!on_null_domain(cpu)))
- raise_softirq(SCHED_SOFTIRQ);
-}
-
-#else /* CONFIG_SMP */
-
-/*
- * on UP we do not need to balance between CPUs:
- */
-static inline void idle_balance(int cpu, struct rq *rq)
-{
-}
-
#endif
DEFINE_PER_CPU(struct kernel_stat, kstat);
@@ -6128,7 +4274,7 @@
if (running)
p->sched_class->set_curr_task(rq);
if (on_rq) {
- enqueue_task(rq, p, 0);
+ enqueue_task(rq, p, 0, oldprio < prio);
check_class_changed(rq, p, prev_class, oldprio, running);
}
@@ -6172,7 +4318,7 @@
delta = p->prio - old_prio;
if (on_rq) {
- enqueue_task(rq, p, 0);
+ enqueue_task(rq, p, 0, false);
/*
* If the task increased its priority or is running and
* lowered its priority, then reschedule its CPU:
@@ -9482,7 +7628,6 @@
tg->rt_rq[cpu] = rt_rq;
init_rt_rq(rt_rq, rq);
rt_rq->tg = tg;
- rt_rq->rt_se = rt_se;
rt_rq->rt_runtime = tg->rt_bandwidth.rt_runtime;
if (add)
list_add(&rt_rq->leaf_rt_rq_list, &rq->leaf_rt_rq_list);
@@ -9513,9 +7658,6 @@
#ifdef CONFIG_RT_GROUP_SCHED
alloc_size += 2 * nr_cpu_ids * sizeof(void **);
#endif
-#ifdef CONFIG_USER_SCHED
- alloc_size *= 2;
-#endif
#ifdef CONFIG_CPUMASK_OFFSTACK
alloc_size += num_possible_cpus() * cpumask_size();
#endif
@@ -9529,13 +7671,6 @@
init_task_group.cfs_rq = (struct cfs_rq **)ptr;
ptr += nr_cpu_ids * sizeof(void **);
-#ifdef CONFIG_USER_SCHED
- root_task_group.se = (struct sched_entity **)ptr;
- ptr += nr_cpu_ids * sizeof(void **);
-
- root_task_group.cfs_rq = (struct cfs_rq **)ptr;
- ptr += nr_cpu_ids * sizeof(void **);
-#endif /* CONFIG_USER_SCHED */
#endif /* CONFIG_FAIR_GROUP_SCHED */
#ifdef CONFIG_RT_GROUP_SCHED
init_task_group.rt_se = (struct sched_rt_entity **)ptr;
@@ -9544,13 +7679,6 @@
init_task_group.rt_rq = (struct rt_rq **)ptr;
ptr += nr_cpu_ids * sizeof(void **);
-#ifdef CONFIG_USER_SCHED
- root_task_group.rt_se = (struct sched_rt_entity **)ptr;
- ptr += nr_cpu_ids * sizeof(void **);
-
- root_task_group.rt_rq = (struct rt_rq **)ptr;
- ptr += nr_cpu_ids * sizeof(void **);
-#endif /* CONFIG_USER_SCHED */
#endif /* CONFIG_RT_GROUP_SCHED */
#ifdef CONFIG_CPUMASK_OFFSTACK
for_each_possible_cpu(i) {
@@ -9570,22 +7698,13 @@
#ifdef CONFIG_RT_GROUP_SCHED
init_rt_bandwidth(&init_task_group.rt_bandwidth,
global_rt_period(), global_rt_runtime());
-#ifdef CONFIG_USER_SCHED
- init_rt_bandwidth(&root_task_group.rt_bandwidth,
- global_rt_period(), RUNTIME_INF);
-#endif /* CONFIG_USER_SCHED */
#endif /* CONFIG_RT_GROUP_SCHED */
-#ifdef CONFIG_GROUP_SCHED
+#ifdef CONFIG_CGROUP_SCHED
list_add(&init_task_group.list, &task_groups);
INIT_LIST_HEAD(&init_task_group.children);
-#ifdef CONFIG_USER_SCHED
- INIT_LIST_HEAD(&root_task_group.children);
- init_task_group.parent = &root_task_group;
- list_add(&init_task_group.siblings, &root_task_group.children);
-#endif /* CONFIG_USER_SCHED */
-#endif /* CONFIG_GROUP_SCHED */
+#endif /* CONFIG_CGROUP_SCHED */
#if defined CONFIG_FAIR_GROUP_SCHED && defined CONFIG_SMP
update_shares_data = __alloc_percpu(nr_cpu_ids * sizeof(unsigned long),
@@ -9625,25 +7744,6 @@
* directly in rq->cfs (i.e init_task_group->se[] = NULL).
*/
init_tg_cfs_entry(&init_task_group, &rq->cfs, NULL, i, 1, NULL);
-#elif defined CONFIG_USER_SCHED
- root_task_group.shares = NICE_0_LOAD;
- init_tg_cfs_entry(&root_task_group, &rq->cfs, NULL, i, 0, NULL);
- /*
- * In case of task-groups formed thr' the user id of tasks,
- * init_task_group represents tasks belonging to root user.
- * Hence it forms a sibling of all subsequent groups formed.
- * In this case, init_task_group gets only a fraction of overall
- * system cpu resource, based on the weight assigned to root
- * user's cpu share (INIT_TASK_GROUP_LOAD). This is accomplished
- * by letting tasks of init_task_group sit in a separate cfs_rq
- * (init_tg_cfs_rq) and having one entity represent this group of
- * tasks in rq->cfs (i.e init_task_group->se[] != NULL).
- */
- init_tg_cfs_entry(&init_task_group,
- &per_cpu(init_tg_cfs_rq, i),
- &per_cpu(init_sched_entity, i), i, 1,
- root_task_group.se[i]);
-
#endif
#endif /* CONFIG_FAIR_GROUP_SCHED */
@@ -9652,12 +7752,6 @@
INIT_LIST_HEAD(&rq->leaf_rt_rq_list);
#ifdef CONFIG_CGROUP_SCHED
init_tg_rt_entry(&init_task_group, &rq->rt, NULL, i, 1, NULL);
-#elif defined CONFIG_USER_SCHED
- init_tg_rt_entry(&root_task_group, &rq->rt, NULL, i, 0, NULL);
- init_tg_rt_entry(&init_task_group,
- &per_cpu(init_rt_rq_var, i),
- &per_cpu(init_sched_rt_entity, i), i, 1,
- root_task_group.rt_se[i]);
#endif
#endif
@@ -9742,7 +7836,7 @@
return (nested == PREEMPT_INATOMIC_BASE + preempt_offset);
}
-void __might_sleep(char *file, int line, int preempt_offset)
+void __might_sleep(const char *file, int line, int preempt_offset)
{
#ifdef in_atomic
static unsigned long prev_jiffy; /* ratelimiting */
@@ -10053,7 +8147,7 @@
}
#endif /* CONFIG_RT_GROUP_SCHED */
-#ifdef CONFIG_GROUP_SCHED
+#ifdef CONFIG_CGROUP_SCHED
static void free_sched_group(struct task_group *tg)
{
free_fair_sched_group(tg);
@@ -10158,11 +8252,11 @@
if (unlikely(running))
tsk->sched_class->set_curr_task(rq);
if (on_rq)
- enqueue_task(rq, tsk, 0);
+ enqueue_task(rq, tsk, 0, false);
task_rq_unlock(rq, &flags);
}
-#endif /* CONFIG_GROUP_SCHED */
+#endif /* CONFIG_CGROUP_SCHED */
#ifdef CONFIG_FAIR_GROUP_SCHED
static void __set_se_shares(struct sched_entity *se, unsigned long shares)
@@ -10304,13 +8398,6 @@
runtime = d->rt_runtime;
}
-#ifdef CONFIG_USER_SCHED
- if (tg == &root_task_group) {
- period = global_rt_period();
- runtime = global_rt_runtime();
- }
-#endif
-
/*
* Cannot have more runtime than the period.
*/
@@ -10930,12 +9017,30 @@
}
/*
+ * When CONFIG_VIRT_CPU_ACCOUNTING is enabled one jiffy can be very large
+ * in cputime_t units. As a result, cpuacct_update_stats calls
+ * percpu_counter_add with values large enough to always overflow the
+ * per cpu batch limit causing bad SMP scalability.
+ *
+ * To fix this we scale percpu_counter_batch by cputime_one_jiffy so we
+ * batch the same amount of time with CONFIG_VIRT_CPU_ACCOUNTING disabled
+ * and enabled. We cap it at INT_MAX which is the largest allowed batch value.
+ */
+#ifdef CONFIG_SMP
+#define CPUACCT_BATCH \
+ min_t(long, percpu_counter_batch * cputime_one_jiffy, INT_MAX)
+#else
+#define CPUACCT_BATCH 0
+#endif
+
+/*
* Charge the system/user time to the task's accounting group.
*/
static void cpuacct_update_stats(struct task_struct *tsk,
enum cpuacct_stat_index idx, cputime_t val)
{
struct cpuacct *ca;
+ int batch = CPUACCT_BATCH;
if (unlikely(!cpuacct_subsys.active))
return;
@@ -10944,7 +9049,7 @@
ca = task_ca(tsk);
do {
- percpu_counter_add(&ca->cpustat[idx], val);
+ __percpu_counter_add(&ca->cpustat[idx], val, batch);
ca = ca->parent;
} while (ca);
rcu_read_unlock();
diff --git a/kernel/sched_cpupri.c b/kernel/sched_cpupri.c
index 597b330..eeb3506c 100644
--- a/kernel/sched_cpupri.c
+++ b/kernel/sched_cpupri.c
@@ -47,9 +47,7 @@
}
#define for_each_cpupri_active(array, idx) \
- for (idx = find_first_bit(array, CPUPRI_NR_PRIORITIES); \
- idx < CPUPRI_NR_PRIORITIES; \
- idx = find_next_bit(array, CPUPRI_NR_PRIORITIES, idx+1))
+ for_each_bit(idx, array, CPUPRI_NR_PRIORITIES)
/**
* cpupri_find - find the best (lowest-pri) CPU in the system
diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c
index 8fe7ee8..ff7692c 100644
--- a/kernel/sched_fair.c
+++ b/kernel/sched_fair.c
@@ -1053,7 +1053,8 @@
* 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 wakeup, bool head)
{
struct cfs_rq *cfs_rq;
struct sched_entity *se = &p->se;
@@ -1815,57 +1816,164 @@
*/
/*
- * Load-balancing iterator. Note: while the runqueue stays locked
- * during the whole iteration, the current task might be
- * dequeued so the iterator has to be dequeue-safe. Here we
- * achieve that by always pre-iterating before returning
- * the current task:
+ * pull_task - move a task from a remote runqueue to the local runqueue.
+ * Both runqueues must be locked.
*/
-static struct task_struct *
-__load_balance_iterator(struct cfs_rq *cfs_rq, struct list_head *next)
+static void pull_task(struct rq *src_rq, struct task_struct *p,
+ struct rq *this_rq, int this_cpu)
{
- struct task_struct *p = NULL;
- struct sched_entity *se;
-
- if (next == &cfs_rq->tasks)
- return NULL;
-
- se = list_entry(next, struct sched_entity, group_node);
- p = task_of(se);
- cfs_rq->balance_iterator = next->next;
-
- return p;
+ deactivate_task(src_rq, p, 0);
+ set_task_cpu(p, this_cpu);
+ activate_task(this_rq, p, 0);
+ check_preempt_curr(this_rq, p, 0);
}
-static struct task_struct *load_balance_start_fair(void *arg)
+/*
+ * can_migrate_task - may task p from runqueue rq be migrated to this_cpu?
+ */
+static
+int can_migrate_task(struct task_struct *p, struct rq *rq, int this_cpu,
+ struct sched_domain *sd, enum cpu_idle_type idle,
+ int *all_pinned)
{
- struct cfs_rq *cfs_rq = arg;
+ int tsk_cache_hot = 0;
+ /*
+ * We do not migrate tasks that are:
+ * 1) running (obviously), or
+ * 2) cannot be migrated to this CPU due to cpus_allowed, or
+ * 3) are cache-hot on their current CPU.
+ */
+ if (!cpumask_test_cpu(this_cpu, &p->cpus_allowed)) {
+ schedstat_inc(p, se.nr_failed_migrations_affine);
+ return 0;
+ }
+ *all_pinned = 0;
- return __load_balance_iterator(cfs_rq, cfs_rq->tasks.next);
+ if (task_running(rq, p)) {
+ schedstat_inc(p, se.nr_failed_migrations_running);
+ return 0;
+ }
+
+ /*
+ * Aggressive migration if:
+ * 1) task is cache cold, or
+ * 2) too many balance attempts have failed.
+ */
+
+ tsk_cache_hot = task_hot(p, rq->clock, sd);
+ if (!tsk_cache_hot ||
+ sd->nr_balance_failed > sd->cache_nice_tries) {
+#ifdef CONFIG_SCHEDSTATS
+ if (tsk_cache_hot) {
+ schedstat_inc(sd, lb_hot_gained[idle]);
+ schedstat_inc(p, se.nr_forced_migrations);
+ }
+#endif
+ return 1;
+ }
+
+ if (tsk_cache_hot) {
+ schedstat_inc(p, se.nr_failed_migrations_hot);
+ return 0;
+ }
+ return 1;
}
-static struct task_struct *load_balance_next_fair(void *arg)
+/*
+ * move_one_task tries to move exactly one task from busiest to this_rq, as
+ * part of active balancing operations within "domain".
+ * Returns 1 if successful and 0 otherwise.
+ *
+ * Called with both runqueues locked.
+ */
+static int
+move_one_task(struct rq *this_rq, int this_cpu, struct rq *busiest,
+ struct sched_domain *sd, enum cpu_idle_type idle)
{
- struct cfs_rq *cfs_rq = arg;
+ struct task_struct *p, *n;
+ struct cfs_rq *cfs_rq;
+ int pinned = 0;
- return __load_balance_iterator(cfs_rq, cfs_rq->balance_iterator);
+ for_each_leaf_cfs_rq(busiest, cfs_rq) {
+ list_for_each_entry_safe(p, n, &cfs_rq->tasks, se.group_node) {
+
+ if (!can_migrate_task(p, busiest, this_cpu,
+ sd, idle, &pinned))
+ continue;
+
+ pull_task(busiest, p, this_rq, this_cpu);
+ /*
+ * Right now, this is only the second place pull_task()
+ * is called, so we can safely collect pull_task()
+ * stats here rather than inside pull_task().
+ */
+ schedstat_inc(sd, lb_gained[idle]);
+ return 1;
+ }
+ }
+
+ return 0;
}
static unsigned long
-__load_balance_fair(struct rq *this_rq, int this_cpu, struct rq *busiest,
- unsigned long max_load_move, struct sched_domain *sd,
- enum cpu_idle_type idle, int *all_pinned, int *this_best_prio,
- struct cfs_rq *cfs_rq)
+balance_tasks(struct rq *this_rq, int this_cpu, struct rq *busiest,
+ unsigned long max_load_move, struct sched_domain *sd,
+ enum cpu_idle_type idle, int *all_pinned,
+ int *this_best_prio, struct cfs_rq *busiest_cfs_rq)
{
- struct rq_iterator cfs_rq_iterator;
+ int loops = 0, pulled = 0, pinned = 0;
+ long rem_load_move = max_load_move;
+ struct task_struct *p, *n;
- cfs_rq_iterator.start = load_balance_start_fair;
- cfs_rq_iterator.next = load_balance_next_fair;
- cfs_rq_iterator.arg = cfs_rq;
+ if (max_load_move == 0)
+ goto out;
- return balance_tasks(this_rq, this_cpu, busiest,
- max_load_move, sd, idle, all_pinned,
- this_best_prio, &cfs_rq_iterator);
+ pinned = 1;
+
+ list_for_each_entry_safe(p, n, &busiest_cfs_rq->tasks, se.group_node) {
+ if (loops++ > sysctl_sched_nr_migrate)
+ break;
+
+ if ((p->se.load.weight >> 1) > rem_load_move ||
+ !can_migrate_task(p, busiest, this_cpu, sd, idle, &pinned))
+ continue;
+
+ pull_task(busiest, p, this_rq, this_cpu);
+ pulled++;
+ rem_load_move -= p->se.load.weight;
+
+#ifdef CONFIG_PREEMPT
+ /*
+ * NEWIDLE balancing is a source of latency, so preemptible
+ * kernels will stop after the first task is pulled to minimize
+ * the critical section.
+ */
+ if (idle == CPU_NEWLY_IDLE)
+ break;
+#endif
+
+ /*
+ * We only want to steal up to the prescribed amount of
+ * weighted load.
+ */
+ if (rem_load_move <= 0)
+ break;
+
+ if (p->prio < *this_best_prio)
+ *this_best_prio = p->prio;
+ }
+out:
+ /*
+ * Right now, this is one of only two places pull_task() is called,
+ * so we can safely collect pull_task() stats here rather than
+ * inside pull_task().
+ */
+ schedstat_add(sd, lb_gained[idle], pulled);
+
+ if (all_pinned)
+ *all_pinned = pinned;
+
+ return max_load_move - rem_load_move;
}
#ifdef CONFIG_FAIR_GROUP_SCHED
@@ -1897,9 +2005,9 @@
rem_load = (u64)rem_load_move * busiest_weight;
rem_load = div_u64(rem_load, busiest_h_load + 1);
- moved_load = __load_balance_fair(this_rq, this_cpu, busiest,
+ moved_load = balance_tasks(this_rq, this_cpu, busiest,
rem_load, sd, idle, all_pinned, this_best_prio,
- tg->cfs_rq[busiest_cpu]);
+ busiest_cfs_rq);
if (!moved_load)
continue;
@@ -1922,35 +2030,1499 @@
struct sched_domain *sd, enum cpu_idle_type idle,
int *all_pinned, int *this_best_prio)
{
- return __load_balance_fair(this_rq, this_cpu, busiest,
+ return balance_tasks(this_rq, this_cpu, busiest,
max_load_move, sd, idle, all_pinned,
this_best_prio, &busiest->cfs);
}
#endif
-static int
-move_one_task_fair(struct rq *this_rq, int this_cpu, struct rq *busiest,
- struct sched_domain *sd, enum cpu_idle_type idle)
+/*
+ * move_tasks tries to move up to max_load_move weighted load from busiest to
+ * this_rq, as part of a balancing operation within domain "sd".
+ * Returns 1 if successful and 0 otherwise.
+ *
+ * Called with both runqueues locked.
+ */
+static int move_tasks(struct rq *this_rq, int this_cpu, struct rq *busiest,
+ unsigned long max_load_move,
+ struct sched_domain *sd, enum cpu_idle_type idle,
+ int *all_pinned)
{
- struct cfs_rq *busy_cfs_rq;
- struct rq_iterator cfs_rq_iterator;
+ unsigned long total_load_moved = 0, load_moved;
+ int this_best_prio = this_rq->curr->prio;
- cfs_rq_iterator.start = load_balance_start_fair;
- cfs_rq_iterator.next = load_balance_next_fair;
+ do {
+ load_moved = load_balance_fair(this_rq, this_cpu, busiest,
+ max_load_move - total_load_moved,
+ sd, idle, all_pinned, &this_best_prio);
- for_each_leaf_cfs_rq(busiest, busy_cfs_rq) {
+ total_load_moved += load_moved;
+
+#ifdef CONFIG_PREEMPT
/*
- * pass busy_cfs_rq argument into
- * load_balance_[start|next]_fair iterators
+ * NEWIDLE balancing is a source of latency, so preemptible
+ * kernels will stop after the first task is pulled to minimize
+ * the critical section.
*/
- cfs_rq_iterator.arg = busy_cfs_rq;
- if (iter_move_one_task(this_rq, this_cpu, busiest, sd, idle,
- &cfs_rq_iterator))
- return 1;
+ if (idle == CPU_NEWLY_IDLE && this_rq->nr_running)
+ break;
+
+ if (raw_spin_is_contended(&this_rq->lock) ||
+ raw_spin_is_contended(&busiest->lock))
+ break;
+#endif
+ } while (load_moved && max_load_move > total_load_moved);
+
+ return total_load_moved > 0;
+}
+
+/********** Helpers for find_busiest_group ************************/
+/*
+ * sd_lb_stats - Structure to store the statistics of a sched_domain
+ * during load balancing.
+ */
+struct sd_lb_stats {
+ struct sched_group *busiest; /* Busiest group in this sd */
+ struct sched_group *this; /* Local group in this sd */
+ unsigned long total_load; /* Total load of all groups in sd */
+ unsigned long total_pwr; /* Total power of all groups in sd */
+ unsigned long avg_load; /* Average load across all groups in sd */
+
+ /** Statistics of this group */
+ unsigned long this_load;
+ unsigned long this_load_per_task;
+ unsigned long this_nr_running;
+
+ /* Statistics of the busiest group */
+ unsigned long max_load;
+ unsigned long busiest_load_per_task;
+ unsigned long busiest_nr_running;
+
+ int group_imb; /* Is there imbalance in this sd */
+#if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
+ int power_savings_balance; /* Is powersave balance needed for this sd */
+ struct sched_group *group_min; /* Least loaded group in sd */
+ struct sched_group *group_leader; /* Group which relieves group_min */
+ unsigned long min_load_per_task; /* load_per_task in group_min */
+ unsigned long leader_nr_running; /* Nr running of group_leader */
+ unsigned long min_nr_running; /* Nr running of group_min */
+#endif
+};
+
+/*
+ * sg_lb_stats - stats of a sched_group required for load_balancing
+ */
+struct sg_lb_stats {
+ unsigned long avg_load; /*Avg load across the CPUs of the group */
+ unsigned long group_load; /* Total load over the CPUs of the group */
+ unsigned long sum_nr_running; /* Nr tasks running in the group */
+ unsigned long sum_weighted_load; /* Weighted load of group's tasks */
+ unsigned long group_capacity;
+ int group_imb; /* Is there an imbalance in the group ? */
+};
+
+/**
+ * group_first_cpu - Returns the first cpu in the cpumask of a sched_group.
+ * @group: The group whose first cpu is to be returned.
+ */
+static inline unsigned int group_first_cpu(struct sched_group *group)
+{
+ return cpumask_first(sched_group_cpus(group));
+}
+
+/**
+ * get_sd_load_idx - Obtain the load index for a given sched domain.
+ * @sd: The sched_domain whose load_idx is to be obtained.
+ * @idle: The Idle status of the CPU for whose sd load_icx is obtained.
+ */
+static inline int get_sd_load_idx(struct sched_domain *sd,
+ enum cpu_idle_type idle)
+{
+ int load_idx;
+
+ switch (idle) {
+ case CPU_NOT_IDLE:
+ load_idx = sd->busy_idx;
+ break;
+
+ case CPU_NEWLY_IDLE:
+ load_idx = sd->newidle_idx;
+ break;
+ default:
+ load_idx = sd->idle_idx;
+ break;
}
+ return load_idx;
+}
+
+
+#if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
+/**
+ * init_sd_power_savings_stats - Initialize power savings statistics for
+ * the given sched_domain, during load balancing.
+ *
+ * @sd: Sched domain whose power-savings statistics are to be initialized.
+ * @sds: Variable containing the statistics for sd.
+ * @idle: Idle status of the CPU at which we're performing load-balancing.
+ */
+static inline void init_sd_power_savings_stats(struct sched_domain *sd,
+ struct sd_lb_stats *sds, enum cpu_idle_type idle)
+{
+ /*
+ * Busy processors will not participate in power savings
+ * balance.
+ */
+ if (idle == CPU_NOT_IDLE || !(sd->flags & SD_POWERSAVINGS_BALANCE))
+ sds->power_savings_balance = 0;
+ else {
+ sds->power_savings_balance = 1;
+ sds->min_nr_running = ULONG_MAX;
+ sds->leader_nr_running = 0;
+ }
+}
+
+/**
+ * update_sd_power_savings_stats - Update the power saving stats for a
+ * sched_domain while performing load balancing.
+ *
+ * @group: sched_group belonging to the sched_domain under consideration.
+ * @sds: Variable containing the statistics of the sched_domain
+ * @local_group: Does group contain the CPU for which we're performing
+ * load balancing ?
+ * @sgs: Variable containing the statistics of the group.
+ */
+static inline void update_sd_power_savings_stats(struct sched_group *group,
+ struct sd_lb_stats *sds, int local_group, struct sg_lb_stats *sgs)
+{
+
+ if (!sds->power_savings_balance)
+ return;
+
+ /*
+ * If the local group is idle or completely loaded
+ * no need to do power savings balance at this domain
+ */
+ if (local_group && (sds->this_nr_running >= sgs->group_capacity ||
+ !sds->this_nr_running))
+ sds->power_savings_balance = 0;
+
+ /*
+ * If a group is already running at full capacity or idle,
+ * don't include that group in power savings calculations
+ */
+ if (!sds->power_savings_balance ||
+ sgs->sum_nr_running >= sgs->group_capacity ||
+ !sgs->sum_nr_running)
+ return;
+
+ /*
+ * Calculate the group which has the least non-idle load.
+ * This is the group from where we need to pick up the load
+ * for saving power
+ */
+ if ((sgs->sum_nr_running < sds->min_nr_running) ||
+ (sgs->sum_nr_running == sds->min_nr_running &&
+ group_first_cpu(group) > group_first_cpu(sds->group_min))) {
+ sds->group_min = group;
+ sds->min_nr_running = sgs->sum_nr_running;
+ sds->min_load_per_task = sgs->sum_weighted_load /
+ sgs->sum_nr_running;
+ }
+
+ /*
+ * Calculate the group which is almost near its
+ * capacity but still has some space to pick up some load
+ * from other group and save more power
+ */
+ if (sgs->sum_nr_running + 1 > sgs->group_capacity)
+ return;
+
+ if (sgs->sum_nr_running > sds->leader_nr_running ||
+ (sgs->sum_nr_running == sds->leader_nr_running &&
+ group_first_cpu(group) < group_first_cpu(sds->group_leader))) {
+ sds->group_leader = group;
+ sds->leader_nr_running = sgs->sum_nr_running;
+ }
+}
+
+/**
+ * check_power_save_busiest_group - see if there is potential for some power-savings balance
+ * @sds: Variable containing the statistics of the sched_domain
+ * under consideration.
+ * @this_cpu: Cpu at which we're currently performing load-balancing.
+ * @imbalance: Variable to store the imbalance.
+ *
+ * Description:
+ * Check if we have potential to perform some power-savings balance.
+ * If yes, set the busiest group to be the least loaded group in the
+ * sched_domain, so that it's CPUs can be put to idle.
+ *
+ * Returns 1 if there is potential to perform power-savings balance.
+ * Else returns 0.
+ */
+static inline int check_power_save_busiest_group(struct sd_lb_stats *sds,
+ int this_cpu, unsigned long *imbalance)
+{
+ if (!sds->power_savings_balance)
+ return 0;
+
+ if (sds->this != sds->group_leader ||
+ sds->group_leader == sds->group_min)
+ return 0;
+
+ *imbalance = sds->min_load_per_task;
+ sds->busiest = sds->group_min;
+
+ return 1;
+
+}
+#else /* CONFIG_SCHED_MC || CONFIG_SCHED_SMT */
+static inline void init_sd_power_savings_stats(struct sched_domain *sd,
+ struct sd_lb_stats *sds, enum cpu_idle_type idle)
+{
+ return;
+}
+
+static inline void update_sd_power_savings_stats(struct sched_group *group,
+ struct sd_lb_stats *sds, int local_group, struct sg_lb_stats *sgs)
+{
+ return;
+}
+
+static inline int check_power_save_busiest_group(struct sd_lb_stats *sds,
+ int this_cpu, unsigned long *imbalance)
+{
return 0;
}
+#endif /* CONFIG_SCHED_MC || CONFIG_SCHED_SMT */
+
+
+unsigned long default_scale_freq_power(struct sched_domain *sd, int cpu)
+{
+ return SCHED_LOAD_SCALE;
+}
+
+unsigned long __weak arch_scale_freq_power(struct sched_domain *sd, int cpu)
+{
+ return default_scale_freq_power(sd, cpu);
+}
+
+unsigned long default_scale_smt_power(struct sched_domain *sd, int cpu)
+{
+ unsigned long weight = cpumask_weight(sched_domain_span(sd));
+ unsigned long smt_gain = sd->smt_gain;
+
+ smt_gain /= weight;
+
+ return smt_gain;
+}
+
+unsigned long __weak arch_scale_smt_power(struct sched_domain *sd, int cpu)
+{
+ return default_scale_smt_power(sd, cpu);
+}
+
+unsigned long scale_rt_power(int cpu)
+{
+ struct rq *rq = cpu_rq(cpu);
+ u64 total, available;
+
+ sched_avg_update(rq);
+
+ total = sched_avg_period() + (rq->clock - rq->age_stamp);
+ available = total - rq->rt_avg;
+
+ if (unlikely((s64)total < SCHED_LOAD_SCALE))
+ total = SCHED_LOAD_SCALE;
+
+ total >>= SCHED_LOAD_SHIFT;
+
+ return div_u64(available, total);
+}
+
+static void update_cpu_power(struct sched_domain *sd, int cpu)
+{
+ unsigned long weight = cpumask_weight(sched_domain_span(sd));
+ unsigned long power = SCHED_LOAD_SCALE;
+ struct sched_group *sdg = sd->groups;
+
+ if (sched_feat(ARCH_POWER))
+ power *= arch_scale_freq_power(sd, cpu);
+ else
+ power *= default_scale_freq_power(sd, cpu);
+
+ power >>= SCHED_LOAD_SHIFT;
+
+ if ((sd->flags & SD_SHARE_CPUPOWER) && weight > 1) {
+ if (sched_feat(ARCH_POWER))
+ power *= arch_scale_smt_power(sd, cpu);
+ else
+ power *= default_scale_smt_power(sd, cpu);
+
+ power >>= SCHED_LOAD_SHIFT;
+ }
+
+ power *= scale_rt_power(cpu);
+ power >>= SCHED_LOAD_SHIFT;
+
+ if (!power)
+ power = 1;
+
+ sdg->cpu_power = power;
+}
+
+static void update_group_power(struct sched_domain *sd, int cpu)
+{
+ struct sched_domain *child = sd->child;
+ struct sched_group *group, *sdg = sd->groups;
+ unsigned long power;
+
+ if (!child) {
+ update_cpu_power(sd, cpu);
+ return;
+ }
+
+ power = 0;
+
+ group = child->groups;
+ do {
+ power += group->cpu_power;
+ group = group->next;
+ } while (group != child->groups);
+
+ sdg->cpu_power = power;
+}
+
+/**
+ * update_sg_lb_stats - Update sched_group's statistics for load balancing.
+ * @sd: The sched_domain whose statistics are to be updated.
+ * @group: sched_group whose statistics are to be updated.
+ * @this_cpu: Cpu for which load balance is currently performed.
+ * @idle: Idle status of this_cpu
+ * @load_idx: Load index of sched_domain of this_cpu for load calc.
+ * @sd_idle: Idle status of the sched_domain containing group.
+ * @local_group: Does group contain this_cpu.
+ * @cpus: Set of cpus considered for load balancing.
+ * @balance: Should we balance.
+ * @sgs: variable to hold the statistics for this group.
+ */
+static inline void update_sg_lb_stats(struct sched_domain *sd,
+ struct sched_group *group, int this_cpu,
+ enum cpu_idle_type idle, int load_idx, int *sd_idle,
+ int local_group, const struct cpumask *cpus,
+ int *balance, struct sg_lb_stats *sgs)
+{
+ unsigned long load, max_cpu_load, min_cpu_load;
+ int i;
+ unsigned int balance_cpu = -1, first_idle_cpu = 0;
+ unsigned long sum_avg_load_per_task;
+ unsigned long avg_load_per_task;
+
+ if (local_group)
+ balance_cpu = group_first_cpu(group);
+
+ /* Tally up the load of all CPUs in the group */
+ sum_avg_load_per_task = avg_load_per_task = 0;
+ max_cpu_load = 0;
+ min_cpu_load = ~0UL;
+
+ for_each_cpu_and(i, sched_group_cpus(group), cpus) {
+ struct rq *rq = cpu_rq(i);
+
+ if (*sd_idle && rq->nr_running)
+ *sd_idle = 0;
+
+ /* Bias balancing toward cpus of our domain */
+ if (local_group) {
+ if (idle_cpu(i) && !first_idle_cpu) {
+ first_idle_cpu = 1;
+ balance_cpu = i;
+ }
+
+ load = target_load(i, load_idx);
+ } else {
+ load = source_load(i, load_idx);
+ if (load > max_cpu_load)
+ max_cpu_load = load;
+ if (min_cpu_load > load)
+ min_cpu_load = load;
+ }
+
+ sgs->group_load += load;
+ sgs->sum_nr_running += rq->nr_running;
+ sgs->sum_weighted_load += weighted_cpuload(i);
+
+ sum_avg_load_per_task += cpu_avg_load_per_task(i);
+ }
+
+ /*
+ * First idle cpu or the first cpu(busiest) in this sched group
+ * is eligible for doing load balancing at this and above
+ * domains. In the newly idle case, we will allow all the cpu's
+ * to do the newly idle load balance.
+ */
+ if (idle != CPU_NEWLY_IDLE && local_group &&
+ balance_cpu != this_cpu) {
+ *balance = 0;
+ return;
+ }
+
+ update_group_power(sd, this_cpu);
+
+ /* Adjust by relative CPU power of the group */
+ sgs->avg_load = (sgs->group_load * SCHED_LOAD_SCALE) / group->cpu_power;
+
+
+ /*
+ * Consider the group unbalanced when the imbalance is larger
+ * than the average weight of two tasks.
+ *
+ * APZ: with cgroup the avg task weight can vary wildly and
+ * might not be a suitable number - should we keep a
+ * normalized nr_running number somewhere that negates
+ * the hierarchy?
+ */
+ avg_load_per_task = (sum_avg_load_per_task * SCHED_LOAD_SCALE) /
+ group->cpu_power;
+
+ if ((max_cpu_load - min_cpu_load) > 2*avg_load_per_task)
+ sgs->group_imb = 1;
+
+ sgs->group_capacity =
+ DIV_ROUND_CLOSEST(group->cpu_power, SCHED_LOAD_SCALE);
+}
+
+/**
+ * update_sd_lb_stats - Update sched_group's statistics for load balancing.
+ * @sd: sched_domain whose statistics are to be updated.
+ * @this_cpu: Cpu for which load balance is currently performed.
+ * @idle: Idle status of this_cpu
+ * @sd_idle: Idle status of the sched_domain containing group.
+ * @cpus: Set of cpus considered for load balancing.
+ * @balance: Should we balance.
+ * @sds: variable to hold the statistics for this sched_domain.
+ */
+static inline void update_sd_lb_stats(struct sched_domain *sd, int this_cpu,
+ enum cpu_idle_type idle, int *sd_idle,
+ const struct cpumask *cpus, int *balance,
+ struct sd_lb_stats *sds)
+{
+ struct sched_domain *child = sd->child;
+ struct sched_group *group = sd->groups;
+ struct sg_lb_stats sgs;
+ int load_idx, prefer_sibling = 0;
+
+ if (child && child->flags & SD_PREFER_SIBLING)
+ prefer_sibling = 1;
+
+ init_sd_power_savings_stats(sd, sds, idle);
+ load_idx = get_sd_load_idx(sd, idle);
+
+ do {
+ int local_group;
+
+ local_group = cpumask_test_cpu(this_cpu,
+ sched_group_cpus(group));
+ memset(&sgs, 0, sizeof(sgs));
+ update_sg_lb_stats(sd, group, this_cpu, idle, load_idx, sd_idle,
+ local_group, cpus, balance, &sgs);
+
+ if (local_group && !(*balance))
+ return;
+
+ sds->total_load += sgs.group_load;
+ sds->total_pwr += group->cpu_power;
+
+ /*
+ * In case the child domain prefers tasks go to siblings
+ * first, lower the group capacity to one so that we'll try
+ * and move all the excess tasks away.
+ */
+ if (prefer_sibling)
+ sgs.group_capacity = min(sgs.group_capacity, 1UL);
+
+ if (local_group) {
+ sds->this_load = sgs.avg_load;
+ sds->this = group;
+ sds->this_nr_running = sgs.sum_nr_running;
+ sds->this_load_per_task = sgs.sum_weighted_load;
+ } else if (sgs.avg_load > sds->max_load &&
+ (sgs.sum_nr_running > sgs.group_capacity ||
+ sgs.group_imb)) {
+ sds->max_load = sgs.avg_load;
+ sds->busiest = group;
+ sds->busiest_nr_running = sgs.sum_nr_running;
+ sds->busiest_load_per_task = sgs.sum_weighted_load;
+ sds->group_imb = sgs.group_imb;
+ }
+
+ update_sd_power_savings_stats(group, sds, local_group, &sgs);
+ group = group->next;
+ } while (group != sd->groups);
+}
+
+/**
+ * fix_small_imbalance - Calculate the minor imbalance that exists
+ * amongst the groups of a sched_domain, during
+ * load balancing.
+ * @sds: Statistics of the sched_domain whose imbalance is to be calculated.
+ * @this_cpu: The cpu at whose sched_domain we're performing load-balance.
+ * @imbalance: Variable to store the imbalance.
+ */
+static inline void fix_small_imbalance(struct sd_lb_stats *sds,
+ int this_cpu, unsigned long *imbalance)
+{
+ unsigned long tmp, pwr_now = 0, pwr_move = 0;
+ unsigned int imbn = 2;
+
+ if (sds->this_nr_running) {
+ sds->this_load_per_task /= sds->this_nr_running;
+ if (sds->busiest_load_per_task >
+ sds->this_load_per_task)
+ imbn = 1;
+ } else
+ sds->this_load_per_task =
+ cpu_avg_load_per_task(this_cpu);
+
+ if (sds->max_load - sds->this_load + sds->busiest_load_per_task >=
+ sds->busiest_load_per_task * imbn) {
+ *imbalance = sds->busiest_load_per_task;
+ return;
+ }
+
+ /*
+ * OK, we don't have enough imbalance to justify moving tasks,
+ * however we may be able to increase total CPU power used by
+ * moving them.
+ */
+
+ pwr_now += sds->busiest->cpu_power *
+ min(sds->busiest_load_per_task, sds->max_load);
+ pwr_now += sds->this->cpu_power *
+ min(sds->this_load_per_task, sds->this_load);
+ pwr_now /= SCHED_LOAD_SCALE;
+
+ /* Amount of load we'd subtract */
+ tmp = (sds->busiest_load_per_task * SCHED_LOAD_SCALE) /
+ sds->busiest->cpu_power;
+ if (sds->max_load > tmp)
+ pwr_move += sds->busiest->cpu_power *
+ min(sds->busiest_load_per_task, sds->max_load - tmp);
+
+ /* Amount of load we'd add */
+ if (sds->max_load * sds->busiest->cpu_power <
+ sds->busiest_load_per_task * SCHED_LOAD_SCALE)
+ tmp = (sds->max_load * sds->busiest->cpu_power) /
+ sds->this->cpu_power;
+ else
+ tmp = (sds->busiest_load_per_task * SCHED_LOAD_SCALE) /
+ sds->this->cpu_power;
+ pwr_move += sds->this->cpu_power *
+ min(sds->this_load_per_task, sds->this_load + tmp);
+ pwr_move /= SCHED_LOAD_SCALE;
+
+ /* Move if we gain throughput */
+ if (pwr_move > pwr_now)
+ *imbalance = sds->busiest_load_per_task;
+}
+
+/**
+ * calculate_imbalance - Calculate the amount of imbalance present within the
+ * groups of a given sched_domain during load balance.
+ * @sds: statistics of the sched_domain whose imbalance is to be calculated.
+ * @this_cpu: Cpu for which currently load balance is being performed.
+ * @imbalance: The variable to store the imbalance.
+ */
+static inline void calculate_imbalance(struct sd_lb_stats *sds, int this_cpu,
+ unsigned long *imbalance)
+{
+ unsigned long max_pull;
+ /*
+ * In the presence of smp nice balancing, certain scenarios can have
+ * max load less than avg load(as we skip the groups at or below
+ * its cpu_power, while calculating max_load..)
+ */
+ if (sds->max_load < sds->avg_load) {
+ *imbalance = 0;
+ return fix_small_imbalance(sds, this_cpu, imbalance);
+ }
+
+ /* Don't want to pull so many tasks that a group would go idle */
+ max_pull = min(sds->max_load - sds->avg_load,
+ sds->max_load - sds->busiest_load_per_task);
+
+ /* How much load to actually move to equalise the imbalance */
+ *imbalance = min(max_pull * sds->busiest->cpu_power,
+ (sds->avg_load - sds->this_load) * sds->this->cpu_power)
+ / SCHED_LOAD_SCALE;
+
+ /*
+ * if *imbalance is less than the average load per runnable task
+ * there is no gaurantee that any tasks will be moved so we'll have
+ * a think about bumping its value to force at least one task to be
+ * moved
+ */
+ if (*imbalance < sds->busiest_load_per_task)
+ return fix_small_imbalance(sds, this_cpu, imbalance);
+
+}
+/******* find_busiest_group() helpers end here *********************/
+
+/**
+ * find_busiest_group - Returns the busiest group within the sched_domain
+ * if there is an imbalance. If there isn't an imbalance, and
+ * the user has opted for power-savings, it returns a group whose
+ * CPUs can be put to idle by rebalancing those tasks elsewhere, if
+ * such a group exists.
+ *
+ * Also calculates the amount of weighted load which should be moved
+ * to restore balance.
+ *
+ * @sd: The sched_domain whose busiest group is to be returned.
+ * @this_cpu: The cpu for which load balancing is currently being performed.
+ * @imbalance: Variable which stores amount of weighted load which should
+ * be moved to restore balance/put a group to idle.
+ * @idle: The idle status of this_cpu.
+ * @sd_idle: The idleness of sd
+ * @cpus: The set of CPUs under consideration for load-balancing.
+ * @balance: Pointer to a variable indicating if this_cpu
+ * is the appropriate cpu to perform load balancing at this_level.
+ *
+ * Returns: - the busiest group if imbalance exists.
+ * - If no imbalance and user has opted for power-savings balance,
+ * return the least loaded group whose CPUs can be
+ * put to idle by rebalancing its tasks onto our group.
+ */
+static struct sched_group *
+find_busiest_group(struct sched_domain *sd, int this_cpu,
+ unsigned long *imbalance, enum cpu_idle_type idle,
+ int *sd_idle, const struct cpumask *cpus, int *balance)
+{
+ struct sd_lb_stats sds;
+
+ memset(&sds, 0, sizeof(sds));
+
+ /*
+ * Compute the various statistics relavent for load balancing at
+ * this level.
+ */
+ update_sd_lb_stats(sd, this_cpu, idle, sd_idle, cpus,
+ balance, &sds);
+
+ /* Cases where imbalance does not exist from POV of this_cpu */
+ /* 1) this_cpu is not the appropriate cpu to perform load balancing
+ * at this level.
+ * 2) There is no busy sibling group to pull from.
+ * 3) This group is the busiest group.
+ * 4) This group is more busy than the avg busieness at this
+ * sched_domain.
+ * 5) The imbalance is within the specified limit.
+ * 6) Any rebalance would lead to ping-pong
+ */
+ if (!(*balance))
+ goto ret;
+
+ if (!sds.busiest || sds.busiest_nr_running == 0)
+ goto out_balanced;
+
+ if (sds.this_load >= sds.max_load)
+ goto out_balanced;
+
+ sds.avg_load = (SCHED_LOAD_SCALE * sds.total_load) / sds.total_pwr;
+
+ if (sds.this_load >= sds.avg_load)
+ goto out_balanced;
+
+ if (100 * sds.max_load <= sd->imbalance_pct * sds.this_load)
+ goto out_balanced;
+
+ sds.busiest_load_per_task /= sds.busiest_nr_running;
+ if (sds.group_imb)
+ sds.busiest_load_per_task =
+ min(sds.busiest_load_per_task, sds.avg_load);
+
+ /*
+ * We're trying to get all the cpus to the average_load, so we don't
+ * want to push ourselves above the average load, nor do we wish to
+ * reduce the max loaded cpu below the average load, as either of these
+ * actions would just result in more rebalancing later, and ping-pong
+ * tasks around. Thus we look for the minimum possible imbalance.
+ * Negative imbalances (*we* are more loaded than anyone else) will
+ * be counted as no imbalance for these purposes -- we can't fix that
+ * by pulling tasks to us. Be careful of negative numbers as they'll
+ * appear as very large values with unsigned longs.
+ */
+ if (sds.max_load <= sds.busiest_load_per_task)
+ goto out_balanced;
+
+ /* Looks like there is an imbalance. Compute it */
+ calculate_imbalance(&sds, this_cpu, imbalance);
+ return sds.busiest;
+
+out_balanced:
+ /*
+ * There is no obvious imbalance. But check if we can do some balancing
+ * to save power.
+ */
+ if (check_power_save_busiest_group(&sds, this_cpu, imbalance))
+ return sds.busiest;
+ret:
+ *imbalance = 0;
+ return NULL;
+}
+
+/*
+ * find_busiest_queue - find the busiest runqueue among the cpus in group.
+ */
+static struct rq *
+find_busiest_queue(struct sched_group *group, enum cpu_idle_type idle,
+ unsigned long imbalance, const struct cpumask *cpus)
+{
+ struct rq *busiest = NULL, *rq;
+ unsigned long max_load = 0;
+ int i;
+
+ for_each_cpu(i, sched_group_cpus(group)) {
+ unsigned long power = power_of(i);
+ unsigned long capacity = DIV_ROUND_CLOSEST(power, SCHED_LOAD_SCALE);
+ unsigned long wl;
+
+ if (!cpumask_test_cpu(i, cpus))
+ continue;
+
+ rq = cpu_rq(i);
+ wl = weighted_cpuload(i);
+
+ /*
+ * When comparing with imbalance, use weighted_cpuload()
+ * which is not scaled with the cpu power.
+ */
+ if (capacity && rq->nr_running == 1 && wl > imbalance)
+ continue;
+
+ /*
+ * For the load comparisons with the other cpu's, consider
+ * the weighted_cpuload() scaled with the cpu power, so that
+ * the load can be moved away from the cpu that is potentially
+ * running at a lower capacity.
+ */
+ wl = (wl * SCHED_LOAD_SCALE) / power;
+
+ if (wl > max_load) {
+ max_load = wl;
+ busiest = rq;
+ }
+ }
+
+ return busiest;
+}
+
+/*
+ * Max backoff if we encounter pinned tasks. Pretty arbitrary value, but
+ * so long as it is large enough.
+ */
+#define MAX_PINNED_INTERVAL 512
+
+/* Working cpumask for load_balance and load_balance_newidle. */
+static DEFINE_PER_CPU(cpumask_var_t, load_balance_tmpmask);
+
+static int need_active_balance(struct sched_domain *sd, int sd_idle, int idle)
+{
+ if (idle == CPU_NEWLY_IDLE) {
+ /*
+ * The only task running in a non-idle cpu can be moved to this
+ * cpu in an attempt to completely freeup the other CPU
+ * package.
+ *
+ * The package power saving logic comes from
+ * find_busiest_group(). If there are no imbalance, then
+ * f_b_g() will return NULL. However when sched_mc={1,2} then
+ * f_b_g() will select a group from which a running task may be
+ * pulled to this cpu in order to make the other package idle.
+ * If there is no opportunity to make a package idle and if
+ * there are no imbalance, then f_b_g() will return NULL and no
+ * action will be taken in load_balance_newidle().
+ *
+ * Under normal task pull operation due to imbalance, there
+ * will be more than one task in the source run queue and
+ * move_tasks() will succeed. ld_moved will be true and this
+ * active balance code will not be triggered.
+ */
+ if (!sd_idle && sd->flags & SD_SHARE_CPUPOWER &&
+ !test_sd_parent(sd, SD_POWERSAVINGS_BALANCE))
+ return 0;
+
+ if (sched_mc_power_savings < POWERSAVINGS_BALANCE_WAKEUP)
+ return 0;
+ }
+
+ return unlikely(sd->nr_balance_failed > sd->cache_nice_tries+2);
+}
+
+/*
+ * Check this_cpu to ensure it is balanced within domain. Attempt to move
+ * tasks if there is an imbalance.
+ */
+static int load_balance(int this_cpu, struct rq *this_rq,
+ struct sched_domain *sd, enum cpu_idle_type idle,
+ int *balance)
+{
+ int ld_moved, all_pinned = 0, active_balance = 0, sd_idle = 0;
+ struct sched_group *group;
+ unsigned long imbalance;
+ struct rq *busiest;
+ unsigned long flags;
+ struct cpumask *cpus = __get_cpu_var(load_balance_tmpmask);
+
+ cpumask_copy(cpus, cpu_active_mask);
+
+ /*
+ * When power savings policy is enabled for the parent domain, idle
+ * sibling can pick up load irrespective of busy siblings. In this case,
+ * let the state of idle sibling percolate up as CPU_IDLE, instead of
+ * portraying it as CPU_NOT_IDLE.
+ */
+ if (idle != CPU_NOT_IDLE && sd->flags & SD_SHARE_CPUPOWER &&
+ !test_sd_parent(sd, SD_POWERSAVINGS_BALANCE))
+ sd_idle = 1;
+
+ schedstat_inc(sd, lb_count[idle]);
+
+redo:
+ update_shares(sd);
+ group = find_busiest_group(sd, this_cpu, &imbalance, idle, &sd_idle,
+ cpus, balance);
+
+ if (*balance == 0)
+ goto out_balanced;
+
+ if (!group) {
+ schedstat_inc(sd, lb_nobusyg[idle]);
+ goto out_balanced;
+ }
+
+ busiest = find_busiest_queue(group, idle, imbalance, cpus);
+ if (!busiest) {
+ schedstat_inc(sd, lb_nobusyq[idle]);
+ goto out_balanced;
+ }
+
+ BUG_ON(busiest == this_rq);
+
+ schedstat_add(sd, lb_imbalance[idle], imbalance);
+
+ ld_moved = 0;
+ if (busiest->nr_running > 1) {
+ /*
+ * Attempt to move tasks. If find_busiest_group has found
+ * an imbalance but busiest->nr_running <= 1, the group is
+ * still unbalanced. ld_moved simply stays zero, so it is
+ * correctly treated as an imbalance.
+ */
+ local_irq_save(flags);
+ double_rq_lock(this_rq, busiest);
+ ld_moved = move_tasks(this_rq, this_cpu, busiest,
+ imbalance, sd, idle, &all_pinned);
+ double_rq_unlock(this_rq, busiest);
+ local_irq_restore(flags);
+
+ /*
+ * some other cpu did the load balance for us.
+ */
+ if (ld_moved && this_cpu != smp_processor_id())
+ resched_cpu(this_cpu);
+
+ /* All tasks on this runqueue were pinned by CPU affinity */
+ if (unlikely(all_pinned)) {
+ cpumask_clear_cpu(cpu_of(busiest), cpus);
+ if (!cpumask_empty(cpus))
+ goto redo;
+ goto out_balanced;
+ }
+ }
+
+ if (!ld_moved) {
+ schedstat_inc(sd, lb_failed[idle]);
+ sd->nr_balance_failed++;
+
+ if (need_active_balance(sd, sd_idle, idle)) {
+ raw_spin_lock_irqsave(&busiest->lock, flags);
+
+ /* don't kick the migration_thread, if the curr
+ * task on busiest cpu can't be moved to this_cpu
+ */
+ if (!cpumask_test_cpu(this_cpu,
+ &busiest->curr->cpus_allowed)) {
+ raw_spin_unlock_irqrestore(&busiest->lock,
+ flags);
+ all_pinned = 1;
+ goto out_one_pinned;
+ }
+
+ if (!busiest->active_balance) {
+ busiest->active_balance = 1;
+ busiest->push_cpu = this_cpu;
+ active_balance = 1;
+ }
+ raw_spin_unlock_irqrestore(&busiest->lock, flags);
+ if (active_balance)
+ wake_up_process(busiest->migration_thread);
+
+ /*
+ * We've kicked active balancing, reset the failure
+ * counter.
+ */
+ sd->nr_balance_failed = sd->cache_nice_tries+1;
+ }
+ } else
+ sd->nr_balance_failed = 0;
+
+ if (likely(!active_balance)) {
+ /* We were unbalanced, so reset the balancing interval */
+ sd->balance_interval = sd->min_interval;
+ } else {
+ /*
+ * If we've begun active balancing, start to back off. This
+ * case may not be covered by the all_pinned logic if there
+ * is only 1 task on the busy runqueue (because we don't call
+ * move_tasks).
+ */
+ if (sd->balance_interval < sd->max_interval)
+ sd->balance_interval *= 2;
+ }
+
+ if (!ld_moved && !sd_idle && sd->flags & SD_SHARE_CPUPOWER &&
+ !test_sd_parent(sd, SD_POWERSAVINGS_BALANCE))
+ ld_moved = -1;
+
+ goto out;
+
+out_balanced:
+ schedstat_inc(sd, lb_balanced[idle]);
+
+ sd->nr_balance_failed = 0;
+
+out_one_pinned:
+ /* tune up the balancing interval */
+ if ((all_pinned && sd->balance_interval < MAX_PINNED_INTERVAL) ||
+ (sd->balance_interval < sd->max_interval))
+ sd->balance_interval *= 2;
+
+ if (!sd_idle && sd->flags & SD_SHARE_CPUPOWER &&
+ !test_sd_parent(sd, SD_POWERSAVINGS_BALANCE))
+ ld_moved = -1;
+ else
+ ld_moved = 0;
+out:
+ if (ld_moved)
+ update_shares(sd);
+ return ld_moved;
+}
+
+/*
+ * idle_balance is called by schedule() if this_cpu is about to become
+ * idle. Attempts to pull tasks from other CPUs.
+ */
+static void idle_balance(int this_cpu, struct rq *this_rq)
+{
+ struct sched_domain *sd;
+ int pulled_task = 0;
+ unsigned long next_balance = jiffies + HZ;
+
+ this_rq->idle_stamp = this_rq->clock;
+
+ if (this_rq->avg_idle < sysctl_sched_migration_cost)
+ return;
+
+ /*
+ * Drop the rq->lock, but keep IRQ/preempt disabled.
+ */
+ raw_spin_unlock(&this_rq->lock);
+
+ for_each_domain(this_cpu, sd) {
+ unsigned long interval;
+ int balance = 1;
+
+ if (!(sd->flags & SD_LOAD_BALANCE))
+ continue;
+
+ if (sd->flags & SD_BALANCE_NEWIDLE) {
+ /* If we've pulled tasks over stop searching: */
+ pulled_task = load_balance(this_cpu, this_rq,
+ sd, CPU_NEWLY_IDLE, &balance);
+ }
+
+ interval = msecs_to_jiffies(sd->balance_interval);
+ if (time_after(next_balance, sd->last_balance + interval))
+ next_balance = sd->last_balance + interval;
+ if (pulled_task) {
+ this_rq->idle_stamp = 0;
+ break;
+ }
+ }
+
+ raw_spin_lock(&this_rq->lock);
+
+ if (pulled_task || time_after(jiffies, this_rq->next_balance)) {
+ /*
+ * We are going idle. next_balance may be set based on
+ * a busy processor. So reset next_balance.
+ */
+ this_rq->next_balance = next_balance;
+ }
+}
+
+/*
+ * active_load_balance is run by migration threads. It pushes running tasks
+ * off the busiest CPU onto idle CPUs. It requires at least 1 task to be
+ * running on each physical CPU where possible, and avoids physical /
+ * logical imbalances.
+ *
+ * Called with busiest_rq locked.
+ */
+static void active_load_balance(struct rq *busiest_rq, int busiest_cpu)
+{
+ int target_cpu = busiest_rq->push_cpu;
+ struct sched_domain *sd;
+ struct rq *target_rq;
+
+ /* Is there any task to move? */
+ if (busiest_rq->nr_running <= 1)
+ return;
+
+ target_rq = cpu_rq(target_cpu);
+
+ /*
+ * This condition is "impossible", if it occurs
+ * we need to fix it. Originally reported by
+ * Bjorn Helgaas on a 128-cpu setup.
+ */
+ BUG_ON(busiest_rq == target_rq);
+
+ /* move a task from busiest_rq to target_rq */
+ double_lock_balance(busiest_rq, target_rq);
+ update_rq_clock(busiest_rq);
+ update_rq_clock(target_rq);
+
+ /* Search for an sd spanning us and the target CPU. */
+ for_each_domain(target_cpu, sd) {
+ if ((sd->flags & SD_LOAD_BALANCE) &&
+ cpumask_test_cpu(busiest_cpu, sched_domain_span(sd)))
+ break;
+ }
+
+ if (likely(sd)) {
+ schedstat_inc(sd, alb_count);
+
+ if (move_one_task(target_rq, target_cpu, busiest_rq,
+ sd, CPU_IDLE))
+ schedstat_inc(sd, alb_pushed);
+ else
+ schedstat_inc(sd, alb_failed);
+ }
+ double_unlock_balance(busiest_rq, target_rq);
+}
+
+#ifdef CONFIG_NO_HZ
+static struct {
+ atomic_t load_balancer;
+ cpumask_var_t cpu_mask;
+ cpumask_var_t ilb_grp_nohz_mask;
+} nohz ____cacheline_aligned = {
+ .load_balancer = ATOMIC_INIT(-1),
+};
+
+int get_nohz_load_balancer(void)
+{
+ return atomic_read(&nohz.load_balancer);
+}
+
+#if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
+/**
+ * lowest_flag_domain - Return lowest sched_domain containing flag.
+ * @cpu: The cpu whose lowest level of sched domain is to
+ * be returned.
+ * @flag: The flag to check for the lowest sched_domain
+ * for the given cpu.
+ *
+ * Returns the lowest sched_domain of a cpu which contains the given flag.
+ */
+static inline struct sched_domain *lowest_flag_domain(int cpu, int flag)
+{
+ struct sched_domain *sd;
+
+ for_each_domain(cpu, sd)
+ if (sd && (sd->flags & flag))
+ break;
+
+ return sd;
+}
+
+/**
+ * for_each_flag_domain - Iterates over sched_domains containing the flag.
+ * @cpu: The cpu whose domains we're iterating over.
+ * @sd: variable holding the value of the power_savings_sd
+ * for cpu.
+ * @flag: The flag to filter the sched_domains to be iterated.
+ *
+ * Iterates over all the scheduler domains for a given cpu that has the 'flag'
+ * set, starting from the lowest sched_domain to the highest.
+ */
+#define for_each_flag_domain(cpu, sd, flag) \
+ for (sd = lowest_flag_domain(cpu, flag); \
+ (sd && (sd->flags & flag)); sd = sd->parent)
+
+/**
+ * is_semi_idle_group - Checks if the given sched_group is semi-idle.
+ * @ilb_group: group to be checked for semi-idleness
+ *
+ * Returns: 1 if the group is semi-idle. 0 otherwise.
+ *
+ * We define a sched_group to be semi idle if it has atleast one idle-CPU
+ * and atleast one non-idle CPU. This helper function checks if the given
+ * sched_group is semi-idle or not.
+ */
+static inline int is_semi_idle_group(struct sched_group *ilb_group)
+{
+ cpumask_and(nohz.ilb_grp_nohz_mask, nohz.cpu_mask,
+ sched_group_cpus(ilb_group));
+
+ /*
+ * A sched_group is semi-idle when it has atleast one busy cpu
+ * and atleast one idle cpu.
+ */
+ if (cpumask_empty(nohz.ilb_grp_nohz_mask))
+ return 0;
+
+ if (cpumask_equal(nohz.ilb_grp_nohz_mask, sched_group_cpus(ilb_group)))
+ return 0;
+
+ return 1;
+}
+/**
+ * find_new_ilb - Finds the optimum idle load balancer for nomination.
+ * @cpu: The cpu which is nominating a new idle_load_balancer.
+ *
+ * Returns: Returns the id of the idle load balancer if it exists,
+ * Else, returns >= nr_cpu_ids.
+ *
+ * This algorithm picks the idle load balancer such that it belongs to a
+ * semi-idle powersavings sched_domain. The idea is to try and avoid
+ * completely idle packages/cores just for the purpose of idle load balancing
+ * when there are other idle cpu's which are better suited for that job.
+ */
+static int find_new_ilb(int cpu)
+{
+ struct sched_domain *sd;
+ struct sched_group *ilb_group;
+
+ /*
+ * Have idle load balancer selection from semi-idle packages only
+ * when power-aware load balancing is enabled
+ */
+ if (!(sched_smt_power_savings || sched_mc_power_savings))
+ goto out_done;
+
+ /*
+ * Optimize for the case when we have no idle CPUs or only one
+ * idle CPU. Don't walk the sched_domain hierarchy in such cases
+ */
+ if (cpumask_weight(nohz.cpu_mask) < 2)
+ goto out_done;
+
+ for_each_flag_domain(cpu, sd, SD_POWERSAVINGS_BALANCE) {
+ ilb_group = sd->groups;
+
+ do {
+ if (is_semi_idle_group(ilb_group))
+ return cpumask_first(nohz.ilb_grp_nohz_mask);
+
+ ilb_group = ilb_group->next;
+
+ } while (ilb_group != sd->groups);
+ }
+
+out_done:
+ return cpumask_first(nohz.cpu_mask);
+}
+#else /* (CONFIG_SCHED_MC || CONFIG_SCHED_SMT) */
+static inline int find_new_ilb(int call_cpu)
+{
+ return cpumask_first(nohz.cpu_mask);
+}
+#endif
+
+/*
+ * This routine will try to nominate the ilb (idle load balancing)
+ * owner among the cpus whose ticks are stopped. ilb owner will do the idle
+ * load balancing on behalf of all those cpus. If all the cpus in the system
+ * go into this tickless mode, then there will be no ilb owner (as there is
+ * no need for one) and all the cpus will sleep till the next wakeup event
+ * arrives...
+ *
+ * For the ilb owner, tick is not stopped. And this tick will be used
+ * for idle load balancing. ilb owner will still be part of
+ * nohz.cpu_mask..
+ *
+ * While stopping the tick, this cpu will become the ilb owner if there
+ * is no other owner. And will be the owner till that cpu becomes busy
+ * or if all cpus in the system stop their ticks at which point
+ * there is no need for ilb owner.
+ *
+ * When the ilb owner becomes busy, it nominates another owner, during the
+ * next busy scheduler_tick()
+ */
+int select_nohz_load_balancer(int stop_tick)
+{
+ int cpu = smp_processor_id();
+
+ if (stop_tick) {
+ cpu_rq(cpu)->in_nohz_recently = 1;
+
+ if (!cpu_active(cpu)) {
+ if (atomic_read(&nohz.load_balancer) != cpu)
+ return 0;
+
+ /*
+ * If we are going offline and still the leader,
+ * give up!
+ */
+ if (atomic_cmpxchg(&nohz.load_balancer, cpu, -1) != cpu)
+ BUG();
+
+ return 0;
+ }
+
+ cpumask_set_cpu(cpu, nohz.cpu_mask);
+
+ /* time for ilb owner also to sleep */
+ if (cpumask_weight(nohz.cpu_mask) == num_active_cpus()) {
+ if (atomic_read(&nohz.load_balancer) == cpu)
+ atomic_set(&nohz.load_balancer, -1);
+ return 0;
+ }
+
+ if (atomic_read(&nohz.load_balancer) == -1) {
+ /* make me the ilb owner */
+ if (atomic_cmpxchg(&nohz.load_balancer, -1, cpu) == -1)
+ return 1;
+ } else if (atomic_read(&nohz.load_balancer) == cpu) {
+ int new_ilb;
+
+ if (!(sched_smt_power_savings ||
+ sched_mc_power_savings))
+ return 1;
+ /*
+ * Check to see if there is a more power-efficient
+ * ilb.
+ */
+ new_ilb = find_new_ilb(cpu);
+ if (new_ilb < nr_cpu_ids && new_ilb != cpu) {
+ atomic_set(&nohz.load_balancer, -1);
+ resched_cpu(new_ilb);
+ return 0;
+ }
+ return 1;
+ }
+ } else {
+ if (!cpumask_test_cpu(cpu, nohz.cpu_mask))
+ return 0;
+
+ cpumask_clear_cpu(cpu, nohz.cpu_mask);
+
+ if (atomic_read(&nohz.load_balancer) == cpu)
+ if (atomic_cmpxchg(&nohz.load_balancer, cpu, -1) != cpu)
+ BUG();
+ }
+ return 0;
+}
+#endif
+
+static DEFINE_SPINLOCK(balancing);
+
+/*
+ * It checks each scheduling domain to see if it is due to be balanced,
+ * and initiates a balancing operation if so.
+ *
+ * Balancing parameters are set up in arch_init_sched_domains.
+ */
+static void rebalance_domains(int cpu, enum cpu_idle_type idle)
+{
+ int balance = 1;
+ struct rq *rq = cpu_rq(cpu);
+ unsigned long interval;
+ struct sched_domain *sd;
+ /* Earliest time when we have to do rebalance again */
+ unsigned long next_balance = jiffies + 60*HZ;
+ int update_next_balance = 0;
+ int need_serialize;
+
+ for_each_domain(cpu, sd) {
+ if (!(sd->flags & SD_LOAD_BALANCE))
+ continue;
+
+ interval = sd->balance_interval;
+ if (idle != CPU_IDLE)
+ interval *= sd->busy_factor;
+
+ /* scale ms to jiffies */
+ interval = msecs_to_jiffies(interval);
+ if (unlikely(!interval))
+ interval = 1;
+ if (interval > HZ*NR_CPUS/10)
+ interval = HZ*NR_CPUS/10;
+
+ need_serialize = sd->flags & SD_SERIALIZE;
+
+ if (need_serialize) {
+ if (!spin_trylock(&balancing))
+ goto out;
+ }
+
+ if (time_after_eq(jiffies, sd->last_balance + interval)) {
+ if (load_balance(cpu, rq, sd, idle, &balance)) {
+ /*
+ * We've pulled tasks over so either we're no
+ * longer idle, or one of our SMT siblings is
+ * not idle.
+ */
+ idle = CPU_NOT_IDLE;
+ }
+ sd->last_balance = jiffies;
+ }
+ if (need_serialize)
+ spin_unlock(&balancing);
+out:
+ if (time_after(next_balance, sd->last_balance + interval)) {
+ next_balance = sd->last_balance + interval;
+ update_next_balance = 1;
+ }
+
+ /*
+ * Stop the load balance at this level. There is another
+ * CPU in our sched group which is doing load balancing more
+ * actively.
+ */
+ if (!balance)
+ break;
+ }
+
+ /*
+ * next_balance will be updated only when there is a need.
+ * When the cpu is attached to null domain for ex, it will not be
+ * updated.
+ */
+ if (likely(update_next_balance))
+ rq->next_balance = next_balance;
+}
+
+/*
+ * run_rebalance_domains is triggered when needed from the scheduler tick.
+ * In CONFIG_NO_HZ case, the idle load balance owner will do the
+ * rebalancing for all the cpus for whom scheduler ticks are stopped.
+ */
+static void run_rebalance_domains(struct softirq_action *h)
+{
+ int this_cpu = smp_processor_id();
+ struct rq *this_rq = cpu_rq(this_cpu);
+ enum cpu_idle_type idle = this_rq->idle_at_tick ?
+ CPU_IDLE : CPU_NOT_IDLE;
+
+ rebalance_domains(this_cpu, idle);
+
+#ifdef CONFIG_NO_HZ
+ /*
+ * If this cpu is the owner for idle load balancing, then do the
+ * balancing on behalf of the other idle cpus whose ticks are
+ * stopped.
+ */
+ if (this_rq->idle_at_tick &&
+ atomic_read(&nohz.load_balancer) == this_cpu) {
+ struct rq *rq;
+ int balance_cpu;
+
+ for_each_cpu(balance_cpu, nohz.cpu_mask) {
+ if (balance_cpu == this_cpu)
+ continue;
+
+ /*
+ * If this cpu gets work to do, stop the load balancing
+ * work being done for other cpus. Next load
+ * balancing owner will pick it up.
+ */
+ if (need_resched())
+ break;
+
+ rebalance_domains(balance_cpu, CPU_IDLE);
+
+ rq = cpu_rq(balance_cpu);
+ if (time_after(this_rq->next_balance, rq->next_balance))
+ this_rq->next_balance = rq->next_balance;
+ }
+ }
+#endif
+}
+
+static inline int on_null_domain(int cpu)
+{
+ return !rcu_dereference(cpu_rq(cpu)->sd);
+}
+
+/*
+ * Trigger the SCHED_SOFTIRQ if it is time to do periodic load balancing.
+ *
+ * In case of CONFIG_NO_HZ, this is the place where we nominate a new
+ * idle load balancing owner or decide to stop the periodic load balancing,
+ * if the whole system is idle.
+ */
+static inline void trigger_load_balance(struct rq *rq, int cpu)
+{
+#ifdef CONFIG_NO_HZ
+ /*
+ * If we were in the nohz mode recently and busy at the current
+ * scheduler tick, then check if we need to nominate new idle
+ * load balancer.
+ */
+ if (rq->in_nohz_recently && !rq->idle_at_tick) {
+ rq->in_nohz_recently = 0;
+
+ if (atomic_read(&nohz.load_balancer) == cpu) {
+ cpumask_clear_cpu(cpu, nohz.cpu_mask);
+ atomic_set(&nohz.load_balancer, -1);
+ }
+
+ if (atomic_read(&nohz.load_balancer) == -1) {
+ int ilb = find_new_ilb(cpu);
+
+ if (ilb < nr_cpu_ids)
+ resched_cpu(ilb);
+ }
+ }
+
+ /*
+ * If this cpu is idle and doing idle load balancing for all the
+ * cpus with ticks stopped, is it time for that to stop?
+ */
+ if (rq->idle_at_tick && atomic_read(&nohz.load_balancer) == cpu &&
+ cpumask_weight(nohz.cpu_mask) == num_online_cpus()) {
+ resched_cpu(cpu);
+ return;
+ }
+
+ /*
+ * If this cpu is idle and the idle load balancing is done by
+ * someone else, then no need raise the SCHED_SOFTIRQ
+ */
+ if (rq->idle_at_tick && atomic_read(&nohz.load_balancer) != cpu &&
+ cpumask_test_cpu(cpu, nohz.cpu_mask))
+ return;
+#endif
+ /* Don't need to rebalance while attached to NULL domain */
+ if (time_after_eq(jiffies, rq->next_balance) &&
+ likely(!on_null_domain(cpu)))
+ raise_softirq(SCHED_SOFTIRQ);
+}
static void rq_online_fair(struct rq *rq)
{
@@ -1962,6 +3534,15 @@
update_sysctl();
}
+#else /* CONFIG_SMP */
+
+/*
+ * on UP we do not need to balance between CPUs:
+ */
+static inline void idle_balance(int cpu, struct rq *rq)
+{
+}
+
#endif /* CONFIG_SMP */
/*
@@ -2076,7 +3657,7 @@
}
#endif
-unsigned int get_rr_interval_fair(struct rq *rq, struct task_struct *task)
+static unsigned int get_rr_interval_fair(struct rq *rq, struct task_struct *task)
{
struct sched_entity *se = &task->se;
unsigned int rr_interval = 0;
@@ -2108,8 +3689,6 @@
#ifdef CONFIG_SMP
.select_task_rq = select_task_rq_fair,
- .load_balance = load_balance_fair,
- .move_one_task = move_one_task_fair,
.rq_online = rq_online_fair,
.rq_offline = rq_offline_fair,
diff --git a/kernel/sched_idletask.c b/kernel/sched_idletask.c
index 5f93b57..a8a6d8a 100644
--- a/kernel/sched_idletask.c
+++ b/kernel/sched_idletask.c
@@ -44,24 +44,6 @@
{
}
-#ifdef CONFIG_SMP
-static unsigned long
-load_balance_idle(struct rq *this_rq, int this_cpu, struct rq *busiest,
- unsigned long max_load_move,
- struct sched_domain *sd, enum cpu_idle_type idle,
- int *all_pinned, int *this_best_prio)
-{
- return 0;
-}
-
-static int
-move_one_task_idle(struct rq *this_rq, int this_cpu, struct rq *busiest,
- struct sched_domain *sd, enum cpu_idle_type idle)
-{
- return 0;
-}
-#endif
-
static void task_tick_idle(struct rq *rq, struct task_struct *curr, int queued)
{
}
@@ -97,7 +79,7 @@
check_preempt_curr(rq, p, 0);
}
-unsigned int get_rr_interval_idle(struct rq *rq, struct task_struct *task)
+static unsigned int get_rr_interval_idle(struct rq *rq, struct task_struct *task)
{
return 0;
}
@@ -119,9 +101,6 @@
#ifdef CONFIG_SMP
.select_task_rq = select_task_rq_idle,
-
- .load_balance = load_balance_idle,
- .move_one_task = move_one_task_idle,
#endif
.set_curr_task = set_curr_task_idle,
diff --git a/kernel/sched_rt.c b/kernel/sched_rt.c
index f48328a..bf3e38f 100644
--- a/kernel/sched_rt.c
+++ b/kernel/sched_rt.c
@@ -194,17 +194,20 @@
return rt_se->my_q;
}
-static void enqueue_rt_entity(struct sched_rt_entity *rt_se);
+static void enqueue_rt_entity(struct sched_rt_entity *rt_se, bool head);
static void dequeue_rt_entity(struct sched_rt_entity *rt_se);
static void sched_rt_rq_enqueue(struct rt_rq *rt_rq)
{
+ int this_cpu = smp_processor_id();
struct task_struct *curr = rq_of_rt_rq(rt_rq)->curr;
- struct sched_rt_entity *rt_se = rt_rq->rt_se;
+ struct sched_rt_entity *rt_se;
+
+ rt_se = rt_rq->tg->rt_se[this_cpu];
if (rt_rq->rt_nr_running) {
if (rt_se && !on_rt_rq(rt_se))
- enqueue_rt_entity(rt_se);
+ enqueue_rt_entity(rt_se, false);
if (rt_rq->highest_prio.curr < curr->prio)
resched_task(curr);
}
@@ -212,7 +215,10 @@
static void sched_rt_rq_dequeue(struct rt_rq *rt_rq)
{
- struct sched_rt_entity *rt_se = rt_rq->rt_se;
+ int this_cpu = smp_processor_id();
+ struct sched_rt_entity *rt_se;
+
+ rt_se = rt_rq->tg->rt_se[this_cpu];
if (rt_se && on_rt_rq(rt_se))
dequeue_rt_entity(rt_se);
@@ -803,7 +809,7 @@
dec_rt_group(rt_se, rt_rq);
}
-static void __enqueue_rt_entity(struct sched_rt_entity *rt_se)
+static void __enqueue_rt_entity(struct sched_rt_entity *rt_se, bool head)
{
struct rt_rq *rt_rq = rt_rq_of_se(rt_se);
struct rt_prio_array *array = &rt_rq->active;
@@ -819,7 +825,10 @@
if (group_rq && (rt_rq_throttled(group_rq) || !group_rq->rt_nr_running))
return;
- list_add_tail(&rt_se->run_list, queue);
+ if (head)
+ list_add(&rt_se->run_list, queue);
+ else
+ list_add_tail(&rt_se->run_list, queue);
__set_bit(rt_se_prio(rt_se), array->bitmap);
inc_rt_tasks(rt_se, rt_rq);
@@ -856,11 +865,11 @@
}
}
-static void enqueue_rt_entity(struct sched_rt_entity *rt_se)
+static void enqueue_rt_entity(struct sched_rt_entity *rt_se, bool head)
{
dequeue_rt_stack(rt_se);
for_each_sched_rt_entity(rt_se)
- __enqueue_rt_entity(rt_se);
+ __enqueue_rt_entity(rt_se, head);
}
static void dequeue_rt_entity(struct sched_rt_entity *rt_se)
@@ -871,21 +880,22 @@
struct rt_rq *rt_rq = group_rt_rq(rt_se);
if (rt_rq && rt_rq->rt_nr_running)
- __enqueue_rt_entity(rt_se);
+ __enqueue_rt_entity(rt_se, false);
}
}
/*
* Adding/removing a task to/from a priority array:
*/
-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 wakeup, bool head)
{
struct sched_rt_entity *rt_se = &p->rt;
if (wakeup)
rt_se->timeout = 0;
- enqueue_rt_entity(rt_se);
+ enqueue_rt_entity(rt_se, head);
if (!task_current(rq, p) && p->rt.nr_cpus_allowed > 1)
enqueue_pushable_task(rq, p);
@@ -1481,24 +1491,6 @@
push_rt_tasks(rq);
}
-static unsigned long
-load_balance_rt(struct rq *this_rq, int this_cpu, struct rq *busiest,
- unsigned long max_load_move,
- struct sched_domain *sd, enum cpu_idle_type idle,
- int *all_pinned, int *this_best_prio)
-{
- /* don't touch RT tasks */
- return 0;
-}
-
-static int
-move_one_task_rt(struct rq *this_rq, int this_cpu, struct rq *busiest,
- struct sched_domain *sd, enum cpu_idle_type idle)
-{
- /* don't touch RT tasks */
- return 0;
-}
-
static void set_cpus_allowed_rt(struct task_struct *p,
const struct cpumask *new_mask)
{
@@ -1721,7 +1713,7 @@
dequeue_pushable_task(rq, p);
}
-unsigned int get_rr_interval_rt(struct rq *rq, struct task_struct *task)
+static unsigned int get_rr_interval_rt(struct rq *rq, struct task_struct *task)
{
/*
* Time slice is 0 for SCHED_FIFO tasks
@@ -1746,8 +1738,6 @@
#ifdef CONFIG_SMP
.select_task_rq = select_task_rq_rt,
- .load_balance = load_balance_rt,
- .move_one_task = move_one_task_rt,
.set_cpus_allowed = set_cpus_allowed_rt,
.rq_online = rq_online_rt,
.rq_offline = rq_offline_rt,
diff --git a/kernel/sys.c b/kernel/sys.c
index 26a6b73..f75bf09 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -569,11 +569,6 @@
if (!new_user)
return -EAGAIN;
- if (!task_can_switch_user(new_user, current)) {
- free_uid(new_user);
- return -EINVAL;
- }
-
if (atomic_read(&new_user->processes) >=
current->signal->rlim[RLIMIT_NPROC].rlim_cur &&
new_user != INIT_USER) {
diff --git a/kernel/user.c b/kernel/user.c
index 46d0165..766467b 100644
--- a/kernel/user.c
+++ b/kernel/user.c
@@ -56,9 +56,6 @@
.sigpending = ATOMIC_INIT(0),
.locked_shm = 0,
.user_ns = &init_user_ns,
-#ifdef CONFIG_USER_SCHED
- .tg = &init_task_group,
-#endif
};
/*
@@ -75,268 +72,6 @@
put_user_ns(up->user_ns);
}
-#ifdef CONFIG_USER_SCHED
-
-static void sched_destroy_user(struct user_struct *up)
-{
- sched_destroy_group(up->tg);
-}
-
-static int sched_create_user(struct user_struct *up)
-{
- int rc = 0;
-
- up->tg = sched_create_group(&root_task_group);
- if (IS_ERR(up->tg))
- rc = -ENOMEM;
-
- set_tg_uid(up);
-
- return rc;
-}
-
-#else /* CONFIG_USER_SCHED */
-
-static void sched_destroy_user(struct user_struct *up) { }
-static int sched_create_user(struct user_struct *up) { return 0; }
-
-#endif /* CONFIG_USER_SCHED */
-
-#if defined(CONFIG_USER_SCHED) && defined(CONFIG_SYSFS)
-
-static struct user_struct *uid_hash_find(uid_t uid, struct hlist_head *hashent)
-{
- struct user_struct *user;
- struct hlist_node *h;
-
- hlist_for_each_entry(user, h, hashent, uidhash_node) {
- if (user->uid == uid) {
- /* possibly resurrect an "almost deleted" object */
- if (atomic_inc_return(&user->__count) == 1)
- cancel_delayed_work(&user->work);
- return user;
- }
- }
-
- return NULL;
-}
-
-static struct kset *uids_kset; /* represents the /sys/kernel/uids/ directory */
-static DEFINE_MUTEX(uids_mutex);
-
-static inline void uids_mutex_lock(void)
-{
- mutex_lock(&uids_mutex);
-}
-
-static inline void uids_mutex_unlock(void)
-{
- mutex_unlock(&uids_mutex);
-}
-
-/* uid directory attributes */
-#ifdef CONFIG_FAIR_GROUP_SCHED
-static ssize_t cpu_shares_show(struct kobject *kobj,
- struct kobj_attribute *attr,
- char *buf)
-{
- struct user_struct *up = container_of(kobj, struct user_struct, kobj);
-
- return sprintf(buf, "%lu\n", sched_group_shares(up->tg));
-}
-
-static ssize_t cpu_shares_store(struct kobject *kobj,
- struct kobj_attribute *attr,
- const char *buf, size_t size)
-{
- struct user_struct *up = container_of(kobj, struct user_struct, kobj);
- unsigned long shares;
- int rc;
-
- sscanf(buf, "%lu", &shares);
-
- rc = sched_group_set_shares(up->tg, shares);
-
- return (rc ? rc : size);
-}
-
-static struct kobj_attribute cpu_share_attr =
- __ATTR(cpu_share, 0644, cpu_shares_show, cpu_shares_store);
-#endif
-
-#ifdef CONFIG_RT_GROUP_SCHED
-static ssize_t cpu_rt_runtime_show(struct kobject *kobj,
- struct kobj_attribute *attr,
- char *buf)
-{
- struct user_struct *up = container_of(kobj, struct user_struct, kobj);
-
- return sprintf(buf, "%ld\n", sched_group_rt_runtime(up->tg));
-}
-
-static ssize_t cpu_rt_runtime_store(struct kobject *kobj,
- struct kobj_attribute *attr,
- const char *buf, size_t size)
-{
- struct user_struct *up = container_of(kobj, struct user_struct, kobj);
- unsigned long rt_runtime;
- int rc;
-
- sscanf(buf, "%ld", &rt_runtime);
-
- rc = sched_group_set_rt_runtime(up->tg, rt_runtime);
-
- return (rc ? rc : size);
-}
-
-static struct kobj_attribute cpu_rt_runtime_attr =
- __ATTR(cpu_rt_runtime, 0644, cpu_rt_runtime_show, cpu_rt_runtime_store);
-
-static ssize_t cpu_rt_period_show(struct kobject *kobj,
- struct kobj_attribute *attr,
- char *buf)
-{
- struct user_struct *up = container_of(kobj, struct user_struct, kobj);
-
- return sprintf(buf, "%lu\n", sched_group_rt_period(up->tg));
-}
-
-static ssize_t cpu_rt_period_store(struct kobject *kobj,
- struct kobj_attribute *attr,
- const char *buf, size_t size)
-{
- struct user_struct *up = container_of(kobj, struct user_struct, kobj);
- unsigned long rt_period;
- int rc;
-
- sscanf(buf, "%lu", &rt_period);
-
- rc = sched_group_set_rt_period(up->tg, rt_period);
-
- return (rc ? rc : size);
-}
-
-static struct kobj_attribute cpu_rt_period_attr =
- __ATTR(cpu_rt_period, 0644, cpu_rt_period_show, cpu_rt_period_store);
-#endif
-
-/* default attributes per uid directory */
-static struct attribute *uids_attributes[] = {
-#ifdef CONFIG_FAIR_GROUP_SCHED
- &cpu_share_attr.attr,
-#endif
-#ifdef CONFIG_RT_GROUP_SCHED
- &cpu_rt_runtime_attr.attr,
- &cpu_rt_period_attr.attr,
-#endif
- NULL
-};
-
-/* the lifetime of user_struct is not managed by the core (now) */
-static void uids_release(struct kobject *kobj)
-{
- return;
-}
-
-static struct kobj_type uids_ktype = {
- .sysfs_ops = &kobj_sysfs_ops,
- .default_attrs = uids_attributes,
- .release = uids_release,
-};
-
-/*
- * Create /sys/kernel/uids/<uid>/cpu_share file for this user
- * We do not create this file for users in a user namespace (until
- * sysfs tagging is implemented).
- *
- * See Documentation/scheduler/sched-design-CFS.txt for ramifications.
- */
-static int uids_user_create(struct user_struct *up)
-{
- struct kobject *kobj = &up->kobj;
- int error;
-
- memset(kobj, 0, sizeof(struct kobject));
- if (up->user_ns != &init_user_ns)
- return 0;
- kobj->kset = uids_kset;
- error = kobject_init_and_add(kobj, &uids_ktype, NULL, "%d", up->uid);
- if (error) {
- kobject_put(kobj);
- goto done;
- }
-
- kobject_uevent(kobj, KOBJ_ADD);
-done:
- return error;
-}
-
-/* create these entries in sysfs:
- * "/sys/kernel/uids" directory
- * "/sys/kernel/uids/0" directory (for root user)
- * "/sys/kernel/uids/0/cpu_share" file (for root user)
- */
-int __init uids_sysfs_init(void)
-{
- uids_kset = kset_create_and_add("uids", NULL, kernel_kobj);
- if (!uids_kset)
- return -ENOMEM;
-
- return uids_user_create(&root_user);
-}
-
-/* delayed work function to remove sysfs directory for a user and free up
- * corresponding structures.
- */
-static void cleanup_user_struct(struct work_struct *w)
-{
- struct user_struct *up = container_of(w, struct user_struct, work.work);
- unsigned long flags;
- int remove_user = 0;
-
- /* Make uid_hash_remove() + sysfs_remove_file() + kobject_del()
- * atomic.
- */
- uids_mutex_lock();
-
- spin_lock_irqsave(&uidhash_lock, flags);
- if (atomic_read(&up->__count) == 0) {
- uid_hash_remove(up);
- remove_user = 1;
- }
- spin_unlock_irqrestore(&uidhash_lock, flags);
-
- if (!remove_user)
- goto done;
-
- if (up->user_ns == &init_user_ns) {
- kobject_uevent(&up->kobj, KOBJ_REMOVE);
- kobject_del(&up->kobj);
- kobject_put(&up->kobj);
- }
-
- sched_destroy_user(up);
- key_put(up->uid_keyring);
- key_put(up->session_keyring);
- kmem_cache_free(uid_cachep, up);
-
-done:
- uids_mutex_unlock();
-}
-
-/* IRQs are disabled and uidhash_lock is held upon function entry.
- * IRQ state (as stored in flags) is restored and uidhash_lock released
- * upon function exit.
- */
-static void free_user(struct user_struct *up, unsigned long flags)
-{
- INIT_DELAYED_WORK(&up->work, cleanup_user_struct);
- schedule_delayed_work(&up->work, msecs_to_jiffies(1000));
- spin_unlock_irqrestore(&uidhash_lock, flags);
-}
-
-#else /* CONFIG_USER_SCHED && CONFIG_SYSFS */
-
static struct user_struct *uid_hash_find(uid_t uid, struct hlist_head *hashent)
{
struct user_struct *user;
@@ -352,11 +87,6 @@
return NULL;
}
-int uids_sysfs_init(void) { return 0; }
-static inline int uids_user_create(struct user_struct *up) { return 0; }
-static inline void uids_mutex_lock(void) { }
-static inline void uids_mutex_unlock(void) { }
-
/* IRQs are disabled and uidhash_lock is held upon function entry.
* IRQ state (as stored in flags) is restored and uidhash_lock released
* upon function exit.
@@ -365,32 +95,11 @@
{
uid_hash_remove(up);
spin_unlock_irqrestore(&uidhash_lock, flags);
- sched_destroy_user(up);
key_put(up->uid_keyring);
key_put(up->session_keyring);
kmem_cache_free(uid_cachep, up);
}
-#endif
-
-#if defined(CONFIG_RT_GROUP_SCHED) && defined(CONFIG_USER_SCHED)
-/*
- * We need to check if a setuid can take place. This function should be called
- * before successfully completing the setuid.
- */
-int task_can_switch_user(struct user_struct *up, struct task_struct *tsk)
-{
-
- return sched_rt_can_attach(up->tg, tsk);
-
-}
-#else
-int task_can_switch_user(struct user_struct *up, struct task_struct *tsk)
-{
- return 1;
-}
-#endif
-
/*
* Locate the user_struct for the passed UID. If found, take a ref on it. The
* caller must undo that ref with free_uid().
@@ -431,8 +140,6 @@
/* Make uid_hash_find() + uids_user_create() + uid_hash_insert()
* atomic.
*/
- uids_mutex_lock();
-
spin_lock_irq(&uidhash_lock);
up = uid_hash_find(uid, hashent);
spin_unlock_irq(&uidhash_lock);
@@ -445,14 +152,8 @@
new->uid = uid;
atomic_set(&new->__count, 1);
- if (sched_create_user(new) < 0)
- goto out_free_user;
-
new->user_ns = get_user_ns(ns);
- if (uids_user_create(new))
- goto out_destoy_sched;
-
/*
* Before adding this, check whether we raced
* on adding the same user already..
@@ -475,17 +176,11 @@
spin_unlock_irq(&uidhash_lock);
}
- uids_mutex_unlock();
-
return up;
-out_destoy_sched:
- sched_destroy_user(new);
put_user_ns(new->user_ns);
-out_free_user:
kmem_cache_free(uid_cachep, new);
out_unlock:
- uids_mutex_unlock();
return NULL;
}
