* and per-CPU runqueues. Cleanups and useful suggestions
* by Davide Libenzi, preemptible kernel bits by Robert Love.
* 2003-09-03 Interactivity tuning by Con Kolivas.
+ * 2004-04-02 Scheduler domains code by Nick Piggin
*/
#include <linux/mm.h>
#include <linux/percpu.h>
#include <linux/kthread.h>
#include <linux/vserver/sched.h>
-#include <linux/vinline.h>
+#include <linux/vs_base.h>
+
+#include <asm/unistd.h>
#ifdef CONFIG_NUMA
#define cpu_to_node_mask(cpu) node_to_cpumask(cpu_to_node(cpu))
#define MAX_SLEEP_AVG (AVG_TIMESLICE * MAX_BONUS)
#define STARVATION_LIMIT (MAX_SLEEP_AVG)
#define NS_MAX_SLEEP_AVG (JIFFIES_TO_NS(MAX_SLEEP_AVG))
-#define NODE_THRESHOLD 125
#define CREDIT_LIMIT 100
/*
(v1) * (v2_max) / (v1_max)
#define DELTA(p) \
- (SCALE(TASK_NICE(p), 40, MAX_USER_PRIO*PRIO_BONUS_RATIO/100) + \
- INTERACTIVE_DELTA)
+ (SCALE(TASK_NICE(p), 40, MAX_BONUS) + INTERACTIVE_DELTA)
#define TASK_INTERACTIVE(p) \
((p)->prio <= (p)->static_prio - DELTA(p))
((MAX_TIMESLICE - MIN_TIMESLICE) * \
(MAX_PRIO-1 - (p)->static_prio) / (MAX_USER_PRIO-1)))
-static inline unsigned int task_timeslice(task_t *p)
+static unsigned int task_timeslice(task_t *p)
{
return BASE_TIMESLICE(p);
}
+#define task_hot(p, now, sd) ((now) - (p)->timestamp < (sd)->cache_hot_time)
+
/*
* These are the runqueue data structures:
*/
typedef struct runqueue runqueue_t;
struct prio_array {
- int nr_active;
+ unsigned int nr_active;
unsigned long bitmap[BITMAP_SIZE];
struct list_head queue[MAX_PRIO];
};
*/
struct runqueue {
spinlock_t lock;
+
+ /*
+ * nr_running and cpu_load should be in the same cacheline because
+ * remote CPUs use both these fields when doing load calculation.
+ */
+ unsigned long nr_running;
+#ifdef CONFIG_SMP
+ unsigned long cpu_load;
+#endif
unsigned long long nr_switches;
- unsigned long nr_running, expired_timestamp, nr_uninterruptible,
- timestamp_last_tick;
+ unsigned long expired_timestamp, nr_uninterruptible;
+ unsigned long long timestamp_last_tick;
task_t *curr, *idle;
struct mm_struct *prev_mm;
prio_array_t *active, *expired, arrays[2];
- int best_expired_prio, prev_cpu_load[NR_CPUS];
-#ifdef CONFIG_NUMA
- atomic_t *node_nr_running;
- int prev_node_load[MAX_NUMNODES];
-#endif
+ int best_expired_prio;
+ atomic_t nr_iowait;
+
+#ifdef CONFIG_SMP
+ struct sched_domain *sd;
+
+ /* For active balancing */
+ int active_balance;
+ int push_cpu;
+
task_t *migration_thread;
struct list_head migration_queue;
+#endif
struct list_head hold_queue;
int idle_tokens;
-
- atomic_t nr_iowait;
};
static DEFINE_PER_CPU(struct runqueue, runqueues);
+#define for_each_domain(cpu, domain) \
+ for (domain = cpu_rq(cpu)->sd; domain; domain = domain->parent)
+
#define cpu_rq(cpu) (&per_cpu(runqueues, (cpu)))
#define this_rq() (&__get_cpu_var(runqueues))
#define task_rq(p) cpu_rq(task_cpu(p))
#define cpu_curr(cpu) (cpu_rq(cpu)->curr)
-extern unsigned long __scheduling_functions_start_here;
-extern unsigned long __scheduling_functions_end_here;
-const unsigned long scheduling_functions_start_here =
- (unsigned long)&__scheduling_functions_start_here;
-const unsigned long scheduling_functions_end_here =
- (unsigned long)&__scheduling_functions_end_here;
-
/*
* Default context-switch locking:
*/
# define task_running(rq, p) ((rq)->curr == (p))
#endif
-#ifdef CONFIG_NUMA
-
-/*
- * Keep track of running tasks.
- */
-
-static atomic_t node_nr_running[MAX_NUMNODES] ____cacheline_maxaligned_in_smp =
- {[0 ...MAX_NUMNODES-1] = ATOMIC_INIT(0)};
-
-static inline void nr_running_init(struct runqueue *rq)
-{
- rq->node_nr_running = &node_nr_running[0];
-}
-
-static inline void nr_running_inc(runqueue_t *rq)
-{
- atomic_inc(rq->node_nr_running);
- rq->nr_running++;
-}
-
-static inline void nr_running_dec(runqueue_t *rq)
-{
- atomic_dec(rq->node_nr_running);
- rq->nr_running--;
-}
-
-__init void node_nr_running_init(void)
-{
- int i;
-
- for (i = 0; i < NR_CPUS; i++) {
- if (cpu_possible(i))
- cpu_rq(i)->node_nr_running =
- &node_nr_running[cpu_to_node(i)];
- }
-}
-
-#else /* !CONFIG_NUMA */
-
-# define nr_running_init(rq) do { } while (0)
-# define nr_running_inc(rq) do { (rq)->nr_running++; } while (0)
-# define nr_running_dec(rq) do { (rq)->nr_running--; } while (0)
-
-#endif /* CONFIG_NUMA */
-
/*
* task_rq_lock - lock the runqueue a given task resides on and disable
* interrupts. Note the ordering: we can safely lookup the task_rq without
* explicitly disabling preemption.
*/
-static inline runqueue_t *task_rq_lock(task_t *p, unsigned long *flags)
+static runqueue_t *task_rq_lock(task_t *p, unsigned long *flags)
{
struct runqueue *rq;
/*
* rq_lock - lock a given runqueue and disable interrupts.
*/
-static inline runqueue_t *this_rq_lock(void)
+static runqueue_t *this_rq_lock(void)
{
runqueue_t *rq;
/*
* Adding/removing a task to/from a priority array:
*/
-static inline void dequeue_task(struct task_struct *p, prio_array_t *array)
+static void dequeue_task(struct task_struct *p, prio_array_t *array)
{
array->nr_active--;
list_del(&p->run_list);
__clear_bit(p->prio, array->bitmap);
}
-static inline void enqueue_task(struct task_struct *p, prio_array_t *array)
+static void enqueue_task(struct task_struct *p, prio_array_t *array)
{
list_add_tail(&p->run_list, array->queue + p->prio);
__set_bit(p->prio, array->bitmap);
p->array = array;
}
+/*
+ * Used by the migration code - we pull tasks from the head of the
+ * remote queue so we want these tasks to show up at the head of the
+ * local queue:
+ */
+static inline void enqueue_task_head(struct task_struct *p, prio_array_t *array)
+{
+ list_add(&p->run_list, array->queue + p->prio);
+ __set_bit(p->prio, array->bitmap);
+ array->nr_active++;
+ p->array = array;
+}
+
/*
* effective_prio - return the priority that is based on the static
* priority but is modified by bonuses/penalties.
static inline void __activate_task(task_t *p, runqueue_t *rq)
{
enqueue_task(p, rq->active);
- nr_running_inc(rq);
+ rq->nr_running++;
+}
+
+/*
+ * __activate_idle_task - move idle task to the _front_ of runqueue.
+ */
+static inline void __activate_idle_task(task_t *p, runqueue_t *rq)
+{
+ enqueue_task_head(p, rq->active);
+ rq->nr_running++;
}
static void recalc_task_prio(task_t *p, unsigned long long now)
* Update all the scheduling statistics stuff. (sleep average
* calculation, priority modifiers, etc.)
*/
-static inline void activate_task(task_t *p, runqueue_t *rq)
+static void activate_task(task_t *p, runqueue_t *rq, int local)
{
- unsigned long long now = sched_clock();
+ unsigned long long now;
+
+ now = sched_clock();
+#ifdef CONFIG_SMP
+ if (!local) {
+ /* Compensate for drifting sched_clock */
+ runqueue_t *this_rq = this_rq();
+ now = (now - this_rq->timestamp_last_tick)
+ + rq->timestamp_last_tick;
+ }
+#endif
recalc_task_prio(p, now);
/*
* deactivate_task - remove a task from the runqueue.
*/
-static inline void deactivate_task(struct task_struct *p, runqueue_t *rq)
+static void deactivate_task(struct task_struct *p, runqueue_t *rq)
{
- nr_running_dec(rq);
+ rq->nr_running--;
if (p->state == TASK_UNINTERRUPTIBLE)
rq->nr_uninterruptible++;
dequeue_task(p, p->array);
* might also involve a cross-CPU call to trigger the scheduler on
* the target CPU.
*/
-static inline void resched_task(task_t *p)
-{
#ifdef CONFIG_SMP
+static void resched_task(task_t *p)
+{
int need_resched, nrpolling;
preempt_disable();
if (!need_resched && !nrpolling && (task_cpu(p) != smp_processor_id()))
smp_send_reschedule(task_cpu(p));
preempt_enable();
+}
#else
+static inline void resched_task(task_t *p)
+{
set_tsk_need_resched(p);
-#endif
}
+#endif
/**
* task_curr - is this task currently executing on a CPU?
}
#ifdef CONFIG_SMP
+enum request_type {
+ REQ_MOVE_TASK,
+ REQ_SET_DOMAIN,
+};
+
typedef struct {
struct list_head list;
+ enum request_type type;
+
+ /* For REQ_MOVE_TASK */
task_t *task;
+ int dest_cpu;
+
+ /* For REQ_SET_DOMAIN */
+ struct sched_domain *sd;
+
struct completion done;
} migration_req_t;
/*
- * The task's runqueue lock must be held, and the new mask must be valid.
+ * The task's runqueue lock must be held.
* Returns true if you have to wait for migration thread.
*/
-static int __set_cpus_allowed(task_t *p, cpumask_t new_mask,
- migration_req_t *req)
+static int migrate_task(task_t *p, int dest_cpu, migration_req_t *req)
{
runqueue_t *rq = task_rq(p);
- p->cpus_allowed = new_mask;
- /*
- * Can the task run on the task's current CPU? If not then
- * migrate the thread off to a proper CPU.
- */
- if (cpu_isset(task_cpu(p), new_mask))
- return 0;
-
/*
* If the task is not on a runqueue (and not running), then
* it is sufficient to simply update the task's cpu field.
*/
if (!p->array && !task_running(rq, p)) {
- set_task_cpu(p, any_online_cpu(p->cpus_allowed));
+ set_task_cpu(p, dest_cpu);
return 0;
}
init_completion(&req->done);
+ req->type = REQ_MOVE_TASK;
req->task = p;
+ req->dest_cpu = dest_cpu;
list_add(&req->list, &rq->migration_queue);
return 1;
}
EXPORT_SYMBOL_GPL(kick_process);
+/*
+ * Return a low guess at the load of a migration-source cpu.
+ *
+ * We want to under-estimate the load of migration sources, to
+ * balance conservatively.
+ */
+static inline unsigned long source_load(int cpu)
+{
+ runqueue_t *rq = cpu_rq(cpu);
+ unsigned long load_now = rq->nr_running * SCHED_LOAD_SCALE;
+
+ return min(rq->cpu_load, load_now);
+}
+
+/*
+ * Return a high guess at the load of a migration-target cpu
+ */
+static inline unsigned long target_load(int cpu)
+{
+ runqueue_t *rq = cpu_rq(cpu);
+ unsigned long load_now = rq->nr_running * SCHED_LOAD_SCALE;
+
+ return max(rq->cpu_load, load_now);
+}
+
+#endif
+
+/*
+ * wake_idle() is useful especially on SMT architectures to wake a
+ * task onto an idle sibling if we would otherwise wake it onto a
+ * busy sibling.
+ *
+ * Returns the CPU we should wake onto.
+ */
+#if defined(ARCH_HAS_SCHED_WAKE_IDLE)
+static int wake_idle(int cpu, task_t *p)
+{
+ cpumask_t tmp;
+ runqueue_t *rq = cpu_rq(cpu);
+ struct sched_domain *sd;
+ int i;
+
+ if (idle_cpu(cpu))
+ return cpu;
+
+ sd = rq->sd;
+ if (!(sd->flags & SD_WAKE_IDLE))
+ return cpu;
+
+ cpus_and(tmp, sd->span, cpu_online_map);
+ for_each_cpu_mask(i, tmp) {
+ if (!cpu_isset(i, p->cpus_allowed))
+ continue;
+
+ if (idle_cpu(i))
+ return i;
+ }
+
+ return cpu;
+}
+#else
+static inline int wake_idle(int cpu, task_t *p)
+{
+ return cpu;
+}
#endif
/***
*/
static int try_to_wake_up(task_t * p, unsigned int state, int sync)
{
+ int cpu, this_cpu, success = 0;
unsigned long flags;
- int success = 0;
long old_state;
runqueue_t *rq;
+#ifdef CONFIG_SMP
+ unsigned long load, this_load;
+ struct sched_domain *sd;
+ int new_cpu;
+#endif
-repeat_lock_task:
rq = task_rq_lock(p, &flags);
old_state = p->state;
- if (old_state & state) {
- if (!p->array) {
+ if (!(old_state & state))
+ goto out;
+
+ if (p->array)
+ goto out_running;
+
+ cpu = task_cpu(p);
+ this_cpu = smp_processor_id();
+
+#ifdef CONFIG_SMP
+ if (unlikely(task_running(rq, p)))
+ goto out_activate;
+
+ new_cpu = cpu;
+
+ if (cpu == this_cpu || unlikely(!cpu_isset(this_cpu, p->cpus_allowed)))
+ goto out_set_cpu;
+
+ load = source_load(cpu);
+ this_load = target_load(this_cpu);
+
+ /*
+ * If sync wakeup then subtract the (maximum possible) effect of
+ * the currently running task from the load of the current CPU:
+ */
+ if (sync)
+ this_load -= SCHED_LOAD_SCALE;
+
+ /* Don't pull the task off an idle CPU to a busy one */
+ if (load < SCHED_LOAD_SCALE/2 && this_load > SCHED_LOAD_SCALE/2)
+ goto out_set_cpu;
+
+ new_cpu = this_cpu; /* Wake to this CPU if we can */
+
+ /*
+ * Scan domains for affine wakeup and passive balancing
+ * possibilities.
+ */
+ for_each_domain(this_cpu, sd) {
+ unsigned int imbalance;
+ /*
+ * Start passive balancing when half the imbalance_pct
+ * limit is reached.
+ */
+ imbalance = sd->imbalance_pct + (sd->imbalance_pct - 100) / 2;
+
+ if ( ((sd->flags & SD_WAKE_AFFINE) &&
+ !task_hot(p, rq->timestamp_last_tick, sd))
+ || ((sd->flags & SD_WAKE_BALANCE) &&
+ imbalance*this_load <= 100*load) ) {
/*
- * Fast-migrate the task if it's not running or runnable
- * currently. Do not violate hard affinity.
+ * Now sd has SD_WAKE_AFFINE and p is cache cold in sd
+ * or sd has SD_WAKE_BALANCE and there is an imbalance
*/
- if (unlikely(sync && !task_running(rq, p) &&
- (task_cpu(p) != smp_processor_id()) &&
- cpu_isset(smp_processor_id(),
- p->cpus_allowed) &&
- !cpu_is_offline(smp_processor_id()))) {
- set_task_cpu(p, smp_processor_id());
- task_rq_unlock(rq, &flags);
- goto repeat_lock_task;
- }
- if (old_state == TASK_UNINTERRUPTIBLE) {
- rq->nr_uninterruptible--;
- /*
- * Tasks on involuntary sleep don't earn
- * sleep_avg beyond just interactive state.
- */
- p->activated = -1;
- }
- if (sync && (task_cpu(p) == smp_processor_id()))
- __activate_task(p, rq);
- else {
- activate_task(p, rq);
- if (TASK_PREEMPTS_CURR(p, rq))
- resched_task(rq->curr);
- }
- success = 1;
+ if (cpu_isset(cpu, sd->span))
+ goto out_set_cpu;
}
- p->state = TASK_RUNNING;
}
+
+ new_cpu = cpu; /* Could not wake to this_cpu. Wake to cpu instead */
+out_set_cpu:
+ new_cpu = wake_idle(new_cpu, p);
+ if (new_cpu != cpu && cpu_isset(new_cpu, p->cpus_allowed)) {
+ set_task_cpu(p, new_cpu);
+ task_rq_unlock(rq, &flags);
+ /* might preempt at this point */
+ rq = task_rq_lock(p, &flags);
+ old_state = p->state;
+ if (!(old_state & state))
+ goto out;
+ if (p->array)
+ goto out_running;
+
+ this_cpu = smp_processor_id();
+ cpu = task_cpu(p);
+ }
+
+out_activate:
+#endif /* CONFIG_SMP */
+ if (old_state == TASK_UNINTERRUPTIBLE) {
+ rq->nr_uninterruptible--;
+ /*
+ * Tasks on involuntary sleep don't earn
+ * sleep_avg beyond just interactive state.
+ */
+ p->activated = -1;
+ }
+
+ /*
+ * Sync wakeups (i.e. those types of wakeups where the waker
+ * has indicated that it will leave the CPU in short order)
+ * don't trigger a preemption, if the woken up task will run on
+ * this cpu. (in this case the 'I will reschedule' promise of
+ * the waker guarantees that the freshly woken up task is going
+ * to be considered on this CPU.)
+ */
+ activate_task(p, rq, cpu == this_cpu);
+ if (!sync || cpu != this_cpu) {
+ if (TASK_PREEMPTS_CURR(p, rq))
+ resched_task(rq->curr);
+ }
+ success = 1;
+
+out_running:
+ p->state = TASK_RUNNING;
+out:
task_rq_unlock(rq, &flags);
return success;
}
+
int fastcall wake_up_process(task_t * p)
{
return try_to_wake_up(p, TASK_STOPPED |
p->timestamp = sched_clock();
if (!current->time_slice) {
/*
- * This case is rare, it happens when the parent has only
- * a single jiffy left from its timeslice. Taking the
+ * This case is rare, it happens when the parent has only
+ * a single jiffy left from its timeslice. Taking the
* runqueue lock is not a problem.
*/
current->time_slice = 1;
list_add_tail(&p->run_list, ¤t->run_list);
p->array = current->array;
p->array->nr_active++;
- nr_running_inc(rq);
+ rq->nr_running++;
}
task_rq_unlock(rq, &flags);
}
* with the lock held can cause deadlocks; see schedule() for
* details.)
*/
-static inline void finish_task_switch(task_t *prev)
+static void finish_task_switch(task_t *prev)
{
runqueue_t *rq = this_rq();
struct mm_struct *mm = rq->prev_mm;
* still held, otherwise prev could be scheduled on another cpu, die
* there before we look at prev->state, and then the reference would
* be dropped twice.
- * Manfred Spraul <manfred@colorfullife.com>
+ * Manfred Spraul <manfred@colorfullife.com>
*/
prev_task_flags = prev->flags;
finish_arch_switch(rq, prev);
{
unsigned long i, sum = 0;
- for (i = 0; i < NR_CPUS; i++)
+ for_each_cpu(i)
sum += cpu_rq(i)->nr_running;
return sum;
{
unsigned long i, sum = 0;
- for_each_cpu(i)
+ for_each_online_cpu(i)
sum += cpu_rq(i)->nr_uninterruptible;
return sum;
{
unsigned long long i, sum = 0;
- for_each_cpu(i)
+ for_each_online_cpu(i)
sum += cpu_rq(i)->nr_switches;
return sum;
{
unsigned long i, sum = 0;
- for_each_cpu(i)
+ for_each_online_cpu(i)
sum += atomic_read(&cpu_rq(i)->nr_iowait);
return sum;
* Note this does not disable interrupts like task_rq_lock,
* you need to do so manually before calling.
*/
-static inline void double_rq_lock(runqueue_t *rq1, runqueue_t *rq2)
+static void double_rq_lock(runqueue_t *rq1, runqueue_t *rq2)
{
if (rq1 == rq2)
spin_lock(&rq1->lock);
* Note this does not restore interrupts like task_rq_unlock,
* you need to do so manually after calling.
*/
-static inline void double_rq_unlock(runqueue_t *rq1, runqueue_t *rq2)
+static void double_rq_unlock(runqueue_t *rq1, runqueue_t *rq2)
{
spin_unlock(&rq1->lock);
if (rq1 != rq2)
spin_unlock(&rq2->lock);
}
-#ifdef CONFIG_NUMA
+enum idle_type
+{
+ IDLE,
+ NOT_IDLE,
+ NEWLY_IDLE,
+};
+
+#ifdef CONFIG_SMP
+
/*
- * If dest_cpu is allowed for this process, migrate the task to it.
- * This is accomplished by forcing the cpu_allowed mask to only
- * allow dest_cpu, which will force the cpu onto dest_cpu. Then
- * the cpu_allowed mask is restored.
+ * find_idlest_cpu - find the least busy runqueue.
*/
-static void sched_migrate_task(task_t *p, int dest_cpu)
+static int find_idlest_cpu(struct task_struct *p, int this_cpu,
+ struct sched_domain *sd)
{
- runqueue_t *rq;
- migration_req_t req;
- unsigned long flags;
- cpumask_t old_mask, new_mask = cpumask_of_cpu(dest_cpu);
+ unsigned long load, min_load, this_load;
+ int i, min_cpu;
+ cpumask_t mask;
- lock_cpu_hotplug();
- rq = task_rq_lock(p, &flags);
- old_mask = p->cpus_allowed;
- if (!cpu_isset(dest_cpu, old_mask) || !cpu_online(dest_cpu))
- goto out;
+ min_cpu = UINT_MAX;
+ min_load = ULONG_MAX;
- /* force the process onto the specified CPU */
- if (__set_cpus_allowed(p, new_mask, &req)) {
- /* Need to wait for migration thread. */
- task_rq_unlock(rq, &flags);
- wake_up_process(rq->migration_thread);
- wait_for_completion(&req.done);
+ cpus_and(mask, sd->span, cpu_online_map);
+ cpus_and(mask, mask, p->cpus_allowed);
- /* If we raced with sys_sched_setaffinity, don't
- * restore mask. */
- rq = task_rq_lock(p, &flags);
- if (likely(cpus_equal(p->cpus_allowed, new_mask))) {
- /* Restore old mask: won't need migration
- * thread, since current cpu is allowed. */
- BUG_ON(__set_cpus_allowed(p, old_mask, NULL));
+ for_each_cpu_mask(i, mask) {
+ load = target_load(i);
+
+ if (load < min_load) {
+ min_cpu = i;
+ min_load = load;
+
+ /* break out early on an idle CPU: */
+ if (!min_load)
+ break;
}
}
-out:
- task_rq_unlock(rq, &flags);
- unlock_cpu_hotplug();
+
+ /* add +1 to account for the new task */
+ this_load = source_load(this_cpu) + SCHED_LOAD_SCALE;
+
+ /*
+ * Would with the addition of the new task to the
+ * current CPU there be an imbalance between this
+ * CPU and the idlest CPU?
+ *
+ * Use half of the balancing threshold - new-context is
+ * a good opportunity to balance.
+ */
+ if (min_load*(100 + (sd->imbalance_pct-100)/2) < this_load*100)
+ return min_cpu;
+
+ return this_cpu;
}
/*
- * Find the least loaded CPU. Slightly favor the current CPU by
- * setting its runqueue length as the minimum to start.
+ * wake_up_forked_thread - wake up a freshly forked thread.
+ *
+ * This function will do some initial scheduler statistics housekeeping
+ * that must be done for every newly created context, and it also does
+ * runqueue balancing.
*/
-static int sched_best_cpu(struct task_struct *p)
+void fastcall wake_up_forked_thread(task_t * p)
{
- int i, minload, load, best_cpu, node = 0;
- cpumask_t cpumask;
+ unsigned long flags;
+ int this_cpu = get_cpu(), cpu;
+ struct sched_domain *tmp, *sd = NULL;
+ runqueue_t *this_rq = cpu_rq(this_cpu), *rq;
- best_cpu = task_cpu(p);
- if (cpu_rq(best_cpu)->nr_running <= 2)
- return best_cpu;
+ /*
+ * Find the largest domain that this CPU is part of that
+ * is willing to balance on clone:
+ */
+ for_each_domain(this_cpu, tmp)
+ if (tmp->flags & SD_BALANCE_CLONE)
+ sd = tmp;
+ if (sd)
+ cpu = find_idlest_cpu(p, this_cpu, sd);
+ else
+ cpu = this_cpu;
- minload = 10000000;
- for_each_node_with_cpus(i) {
- /*
- * Node load is always divided by nr_cpus_node to normalise
- * load values in case cpu count differs from node to node.
- * We first multiply node_nr_running by 10 to get a little
- * better resolution.
- */
- load = 10 * atomic_read(&node_nr_running[i]) / nr_cpus_node(i);
- if (load < minload) {
- minload = load;
- node = i;
- }
+ local_irq_save(flags);
+lock_again:
+ rq = cpu_rq(cpu);
+ double_rq_lock(this_rq, rq);
+
+ BUG_ON(p->state != TASK_RUNNING);
+
+ /*
+ * We did find_idlest_cpu() unlocked, so in theory
+ * the mask could have changed - just dont migrate
+ * in this case:
+ */
+ if (unlikely(!cpu_isset(cpu, p->cpus_allowed))) {
+ cpu = this_cpu;
+ double_rq_unlock(this_rq, rq);
+ goto lock_again;
}
+ /*
+ * We decrease the sleep average of forking parents
+ * and children as well, to keep max-interactive tasks
+ * from forking tasks that are max-interactive.
+ */
+ current->sleep_avg = JIFFIES_TO_NS(CURRENT_BONUS(current) *
+ PARENT_PENALTY / 100 * MAX_SLEEP_AVG / MAX_BONUS);
- minload = 10000000;
- cpumask = node_to_cpumask(node);
- for (i = 0; i < NR_CPUS; ++i) {
- if (!cpu_isset(i, cpumask))
- continue;
- if (cpu_rq(i)->nr_running < minload) {
- best_cpu = i;
- minload = cpu_rq(i)->nr_running;
+ p->sleep_avg = JIFFIES_TO_NS(CURRENT_BONUS(p) *
+ CHILD_PENALTY / 100 * MAX_SLEEP_AVG / MAX_BONUS);
+
+ p->interactive_credit = 0;
+
+ p->prio = effective_prio(p);
+ set_task_cpu(p, cpu);
+
+ if (cpu == this_cpu) {
+ if (unlikely(!current->array))
+ __activate_task(p, rq);
+ else {
+ p->prio = current->prio;
+ list_add_tail(&p->run_list, ¤t->run_list);
+ p->array = current->array;
+ p->array->nr_active++;
+ rq->nr_running++;
}
+ } else {
+ /* Not the local CPU - must adjust timestamp */
+ p->timestamp = (p->timestamp - this_rq->timestamp_last_tick)
+ + rq->timestamp_last_tick;
+ __activate_task(p, rq);
+ if (TASK_PREEMPTS_CURR(p, rq))
+ resched_task(rq->curr);
}
- return best_cpu;
+
+ double_rq_unlock(this_rq, rq);
+ local_irq_restore(flags);
+ put_cpu();
}
-void sched_balance_exec(void)
+/*
+ * If dest_cpu is allowed for this process, migrate the task to it.
+ * This is accomplished by forcing the cpu_allowed mask to only
+ * allow dest_cpu, which will force the cpu onto dest_cpu. Then
+ * the cpu_allowed mask is restored.
+ */
+static void sched_migrate_task(task_t *p, int dest_cpu)
{
- int new_cpu;
+ migration_req_t req;
+ runqueue_t *rq;
+ unsigned long flags;
- if (numnodes > 1) {
- new_cpu = sched_best_cpu(current);
- if (new_cpu != smp_processor_id())
- sched_migrate_task(current, new_cpu);
+ rq = task_rq_lock(p, &flags);
+ if (!cpu_isset(dest_cpu, p->cpus_allowed)
+ || unlikely(cpu_is_offline(dest_cpu)))
+ goto out;
+
+ /* force the process onto the specified CPU */
+ if (migrate_task(p, dest_cpu, &req)) {
+ /* Need to wait for migration thread (might exit: take ref). */
+ struct task_struct *mt = rq->migration_thread;
+ get_task_struct(mt);
+ task_rq_unlock(rq, &flags);
+ wake_up_process(mt);
+ put_task_struct(mt);
+ wait_for_completion(&req.done);
+ return;
}
+out:
+ task_rq_unlock(rq, &flags);
}
/*
- * Find the busiest node. All previous node loads contribute with a
- * geometrically deccaying weight to the load measure:
- * load_{t} = load_{t-1}/2 + nr_node_running_{t}
- * This way sudden load peaks are flattened out a bit.
- * Node load is divided by nr_cpus_node() in order to compare nodes
- * of different cpu count but also [first] multiplied by 10 to
- * provide better resolution.
+ * sched_balance_exec(): find the highest-level, exec-balance-capable
+ * domain and try to migrate the task to the least loaded CPU.
+ *
+ * execve() is a valuable balancing opportunity, because at this point
+ * the task has the smallest effective memory and cache footprint.
*/
-static int find_busiest_node(int this_node)
+void sched_balance_exec(void)
{
- int i, node = -1, load, this_load, maxload;
+ struct sched_domain *tmp, *sd = NULL;
+ int new_cpu, this_cpu = get_cpu();
- if (!nr_cpus_node(this_node))
- return node;
- this_load = maxload = (this_rq()->prev_node_load[this_node] >> 1)
- + (10 * atomic_read(&node_nr_running[this_node])
- / nr_cpus_node(this_node));
- this_rq()->prev_node_load[this_node] = this_load;
- for_each_node_with_cpus(i) {
- if (i == this_node)
- continue;
- load = (this_rq()->prev_node_load[i] >> 1)
- + (10 * atomic_read(&node_nr_running[i])
- / nr_cpus_node(i));
- this_rq()->prev_node_load[i] = load;
- if (load > maxload && (100*load > NODE_THRESHOLD*this_load)) {
- maxload = load;
- node = i;
+ /* Prefer the current CPU if there's only this task running */
+ if (this_rq()->nr_running <= 1)
+ goto out;
+
+ for_each_domain(this_cpu, tmp)
+ if (tmp->flags & SD_BALANCE_EXEC)
+ sd = tmp;
+
+ if (sd) {
+ new_cpu = find_idlest_cpu(current, this_cpu, sd);
+ if (new_cpu != this_cpu) {
+ put_cpu();
+ sched_migrate_task(current, new_cpu);
+ return;
}
}
- return node;
+out:
+ put_cpu();
}
-#endif /* CONFIG_NUMA */
-
-#ifdef CONFIG_SMP
-
/*
- * double_lock_balance - lock the busiest runqueue
- *
- * this_rq is locked already. Recalculate nr_running if we have to
- * drop the runqueue lock.
+ * double_lock_balance - lock the busiest runqueue, this_rq is locked already.
*/
-static inline
-unsigned int double_lock_balance(runqueue_t *this_rq, runqueue_t *busiest,
- int this_cpu, int idle,
- unsigned int nr_running)
+static void double_lock_balance(runqueue_t *this_rq, runqueue_t *busiest)
{
if (unlikely(!spin_trylock(&busiest->lock))) {
if (busiest < this_rq) {
spin_unlock(&this_rq->lock);
spin_lock(&busiest->lock);
spin_lock(&this_rq->lock);
- /* Need to recalculate nr_running */
- if (idle || (this_rq->nr_running >
- this_rq->prev_cpu_load[this_cpu]))
- nr_running = this_rq->nr_running;
- else
- nr_running = this_rq->prev_cpu_load[this_cpu];
} else
spin_lock(&busiest->lock);
}
- return nr_running;
-}
-
-/*
- * find_busiest_queue - find the busiest runqueue among the cpus in cpumask.
- */
-static inline
-runqueue_t *find_busiest_queue(runqueue_t *this_rq, int this_cpu, int idle,
- int *imbalance, cpumask_t cpumask)
-{
- int nr_running, load, max_load, i;
- runqueue_t *busiest, *rq_src;
-
- /*
- * We search all runqueues to find the most busy one.
- * We do this lockless to reduce cache-bouncing overhead,
- * we re-check the 'best' source CPU later on again, with
- * the lock held.
- *
- * We fend off statistical fluctuations in runqueue lengths by
- * saving the runqueue length (as seen by the balancing CPU) during
- * the previous load-balancing operation and using the smaller one
- * of the current and saved lengths. If a runqueue is long enough
- * for a longer amount of time then we recognize it and pull tasks
- * from it.
- *
- * The 'current runqueue length' is a statistical maximum variable,
- * for that one we take the longer one - to avoid fluctuations in
- * the other direction. So for a load-balance to happen it needs
- * stable long runqueue on the target CPU and stable short runqueue
- * on the local runqueue.
- *
- * We make an exception if this CPU is about to become idle - in
- * that case we are less picky about moving a task across CPUs and
- * take what can be taken.
- */
- if (idle || (this_rq->nr_running > this_rq->prev_cpu_load[this_cpu]))
- nr_running = this_rq->nr_running;
- else
- nr_running = this_rq->prev_cpu_load[this_cpu];
-
- busiest = NULL;
- max_load = 1;
- for (i = 0; i < NR_CPUS; i++) {
- if (!cpu_isset(i, cpumask))
- continue;
-
- rq_src = cpu_rq(i);
- if (idle || (rq_src->nr_running < this_rq->prev_cpu_load[i]))
- load = rq_src->nr_running;
- else
- load = this_rq->prev_cpu_load[i];
- this_rq->prev_cpu_load[i] = rq_src->nr_running;
-
- if ((load > max_load) && (rq_src != this_rq)) {
- busiest = rq_src;
- max_load = load;
- }
- }
-
- if (likely(!busiest))
- goto out;
-
- *imbalance = max_load - nr_running;
-
- /* It needs an at least ~25% imbalance to trigger balancing. */
- if (!idle && ((*imbalance)*4 < max_load)) {
- busiest = NULL;
- goto out;
- }
-
- nr_running = double_lock_balance(this_rq, busiest, this_cpu,
- idle, nr_running);
- /*
- * Make sure nothing changed since we checked the
- * runqueue length.
- */
- if (busiest->nr_running <= nr_running) {
- spin_unlock(&busiest->lock);
- busiest = NULL;
- }
-out:
- return busiest;
}
/*
*/
static inline
void pull_task(runqueue_t *src_rq, prio_array_t *src_array, task_t *p,
- runqueue_t *this_rq, int this_cpu)
+ runqueue_t *this_rq, prio_array_t *this_array, int this_cpu)
{
dequeue_task(p, src_array);
- nr_running_dec(src_rq);
+ src_rq->nr_running--;
set_task_cpu(p, this_cpu);
- nr_running_inc(this_rq);
- enqueue_task(p, this_rq->active);
- p->timestamp = sched_clock() -
- (src_rq->timestamp_last_tick - p->timestamp);
+ this_rq->nr_running++;
+ enqueue_task(p, this_array);
+ p->timestamp = (p->timestamp - src_rq->timestamp_last_tick)
+ + this_rq->timestamp_last_tick;
/*
* Note that idle threads have a prio of MAX_PRIO, for this test
* to be always true for them.
*/
if (TASK_PREEMPTS_CURR(p, this_rq))
- set_need_resched();
+ resched_task(this_rq->curr);
}
/*
* can_migrate_task - may task p from runqueue rq be migrated to this_cpu?
*/
static inline
-int can_migrate_task(task_t *tsk, runqueue_t *rq, int this_cpu, int idle)
+int can_migrate_task(task_t *p, runqueue_t *rq, int this_cpu,
+ struct sched_domain *sd, enum idle_type idle)
{
- unsigned long delta = rq->timestamp_last_tick - tsk->timestamp;
-
/*
* 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 (task_running(rq, tsk))
- return 0;
- if (!cpu_isset(this_cpu, tsk->cpus_allowed))
+ if (task_running(rq, p))
return 0;
- if (!idle && (delta <= JIFFIES_TO_NS(cache_decay_ticks)))
+ if (!cpu_isset(this_cpu, p->cpus_allowed))
return 0;
+
+ /* Aggressive migration if we've failed balancing */
+ if (idle == NEWLY_IDLE ||
+ sd->nr_balance_failed < sd->cache_nice_tries) {
+ if (task_hot(p, rq->timestamp_last_tick, sd))
+ return 0;
+ }
+
return 1;
}
/*
- * Current runqueue is empty, or rebalance tick: if there is an
- * inbalance (current runqueue is too short) then pull from
- * busiest runqueue(s).
+ * move_tasks tries to move up to max_nr_move tasks from busiest to this_rq,
+ * as part of a balancing operation within "domain". Returns the number of
+ * tasks moved.
*
- * We call this with the current runqueue locked,
- * irqs disabled.
+ * Called with both runqueues locked.
*/
-static void load_balance(runqueue_t *this_rq, int idle, cpumask_t cpumask)
+static int move_tasks(runqueue_t *this_rq, int this_cpu, runqueue_t *busiest,
+ unsigned long max_nr_move, struct sched_domain *sd,
+ enum idle_type idle)
{
- int imbalance, idx, this_cpu = smp_processor_id();
- runqueue_t *busiest;
- prio_array_t *array;
+ prio_array_t *array, *dst_array;
struct list_head *head, *curr;
+ int idx, pulled = 0;
task_t *tmp;
- if (cpu_is_offline(this_cpu))
- goto out;
-
- busiest = find_busiest_queue(this_rq, this_cpu, idle,
- &imbalance, cpumask);
- if (!busiest)
+ if (max_nr_move <= 0 || busiest->nr_running <= 1)
goto out;
- /*
- * We only want to steal a number of tasks equal to 1/2 the imbalance,
- * otherwise we'll just shift the imbalance to the new queue:
- */
- imbalance /= 2;
-
/*
* We first consider expired tasks. Those will likely not be
* executed in the near future, and they are most likely to
* be cache-cold, thus switching CPUs has the least effect
* on them.
*/
- if (busiest->expired->nr_active)
+ if (busiest->expired->nr_active) {
array = busiest->expired;
- else
+ dst_array = this_rq->expired;
+ } else {
array = busiest->active;
+ dst_array = this_rq->active;
+ }
new_array:
/* Start searching at priority 0: */
else
idx = find_next_bit(array->bitmap, MAX_PRIO, idx);
if (idx >= MAX_PRIO) {
- if (array == busiest->expired) {
+ if (array == busiest->expired && busiest->active->nr_active) {
array = busiest->active;
+ dst_array = this_rq->active;
goto new_array;
}
- goto out_unlock;
+ goto out;
+ }
+
+ head = array->queue + idx;
+ curr = head->prev;
+skip_queue:
+ tmp = list_entry(curr, task_t, run_list);
+
+ curr = curr->prev;
+
+ if (!can_migrate_task(tmp, busiest, this_cpu, sd, idle)) {
+ if (curr != head)
+ goto skip_queue;
+ idx++;
+ goto skip_bitmap;
+ }
+ pull_task(busiest, array, tmp, this_rq, dst_array, this_cpu);
+ pulled++;
+
+ /* We only want to steal up to the prescribed number of tasks. */
+ if (pulled < max_nr_move) {
+ if (curr != head)
+ goto skip_queue;
+ idx++;
+ goto skip_bitmap;
+ }
+out:
+ return pulled;
+}
+
+/*
+ * find_busiest_group finds and returns the busiest CPU group within the
+ * domain. It calculates and returns the number of tasks which should be
+ * moved to restore balance via the imbalance parameter.
+ */
+static struct sched_group *
+find_busiest_group(struct sched_domain *sd, int this_cpu,
+ unsigned long *imbalance, enum idle_type idle)
+{
+ struct sched_group *busiest = NULL, *this = NULL, *group = sd->groups;
+ unsigned long max_load, avg_load, total_load, this_load, total_pwr;
+
+ max_load = this_load = total_load = total_pwr = 0;
+
+ do {
+ cpumask_t tmp;
+ unsigned long load;
+ int local_group;
+ int i, nr_cpus = 0;
+
+ local_group = cpu_isset(this_cpu, group->cpumask);
+
+ /* Tally up the load of all CPUs in the group */
+ avg_load = 0;
+ cpus_and(tmp, group->cpumask, cpu_online_map);
+ if (unlikely(cpus_empty(tmp)))
+ goto nextgroup;
+
+ for_each_cpu_mask(i, tmp) {
+ /* Bias balancing toward cpus of our domain */
+ if (local_group)
+ load = target_load(i);
+ else
+ load = source_load(i);
+
+ nr_cpus++;
+ avg_load += load;
+ }
+
+ if (!nr_cpus)
+ goto nextgroup;
+
+ total_load += avg_load;
+ total_pwr += group->cpu_power;
+
+ /* Adjust by relative CPU power of the group */
+ avg_load = (avg_load * SCHED_LOAD_SCALE) / group->cpu_power;
+
+ if (local_group) {
+ this_load = avg_load;
+ this = group;
+ goto nextgroup;
+ } else if (avg_load > max_load) {
+ max_load = avg_load;
+ busiest = group;
+ }
+nextgroup:
+ group = group->next;
+ } while (group != sd->groups);
+
+ if (!busiest || this_load >= max_load)
+ goto out_balanced;
+
+ avg_load = (SCHED_LOAD_SCALE * total_load) / total_pwr;
+
+ if (this_load >= avg_load ||
+ 100*max_load <= sd->imbalance_pct*this_load)
+ goto out_balanced;
+
+ /*
+ * 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.
+ */
+ *imbalance = min(max_load - avg_load, avg_load - this_load);
+
+ /* How much load to actually move to equalise the imbalance */
+ *imbalance = (*imbalance * min(busiest->cpu_power, this->cpu_power))
+ / SCHED_LOAD_SCALE;
+
+ if (*imbalance < SCHED_LOAD_SCALE - 1) {
+ unsigned long pwr_now = 0, pwr_move = 0;
+ unsigned long tmp;
+
+ if (max_load - this_load >= SCHED_LOAD_SCALE*2) {
+ *imbalance = 1;
+ return busiest;
+ }
+
+ /*
+ * 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 += busiest->cpu_power*min(SCHED_LOAD_SCALE, max_load);
+ pwr_now += this->cpu_power*min(SCHED_LOAD_SCALE, this_load);
+ pwr_now /= SCHED_LOAD_SCALE;
+
+ /* Amount of load we'd subtract */
+ tmp = SCHED_LOAD_SCALE*SCHED_LOAD_SCALE/busiest->cpu_power;
+ if (max_load > tmp)
+ pwr_move += busiest->cpu_power*min(SCHED_LOAD_SCALE,
+ max_load - tmp);
+
+ /* Amount of load we'd add */
+ tmp = SCHED_LOAD_SCALE*SCHED_LOAD_SCALE/this->cpu_power;
+ if (max_load < tmp)
+ tmp = max_load;
+ pwr_move += this->cpu_power*min(SCHED_LOAD_SCALE, this_load + tmp);
+ pwr_move /= SCHED_LOAD_SCALE;
+
+ /* Move if we gain another 8th of a CPU worth of throughput */
+ if (pwr_move < pwr_now + SCHED_LOAD_SCALE / 8)
+ goto out_balanced;
+
+ *imbalance = 1;
+ return busiest;
+ }
+
+ /* Get rid of the scaling factor, rounding down as we divide */
+ *imbalance = (*imbalance + 1) / SCHED_LOAD_SCALE;
+
+ return busiest;
+
+out_balanced:
+ if (busiest && (idle == NEWLY_IDLE ||
+ (idle == IDLE && max_load > SCHED_LOAD_SCALE)) ) {
+ *imbalance = 1;
+ return busiest;
+ }
+
+ *imbalance = 0;
+ return NULL;
+}
+
+/*
+ * find_busiest_queue - find the busiest runqueue among the cpus in group.
+ */
+static runqueue_t *find_busiest_queue(struct sched_group *group)
+{
+ cpumask_t tmp;
+ unsigned long load, max_load = 0;
+ runqueue_t *busiest = NULL;
+ int i;
+
+ cpus_and(tmp, group->cpumask, cpu_online_map);
+ for_each_cpu_mask(i, tmp) {
+ load = source_load(i);
+
+ if (load > max_load) {
+ max_load = load;
+ busiest = cpu_rq(i);
+ }
+ }
+
+ return busiest;
+}
+
+/*
+ * Check this_cpu to ensure it is balanced within domain. Attempt to move
+ * tasks if there is an imbalance.
+ *
+ * Called with this_rq unlocked.
+ */
+static int load_balance(int this_cpu, runqueue_t *this_rq,
+ struct sched_domain *sd, enum idle_type idle)
+{
+ struct sched_group *group;
+ runqueue_t *busiest;
+ unsigned long imbalance;
+ int nr_moved;
+
+ spin_lock(&this_rq->lock);
+
+ group = find_busiest_group(sd, this_cpu, &imbalance, idle);
+ if (!group)
+ goto out_balanced;
+
+ busiest = find_busiest_queue(group);
+ if (!busiest)
+ goto out_balanced;
+ /*
+ * This should be "impossible", but since load
+ * balancing is inherently racy and statistical,
+ * it could happen in theory.
+ */
+ if (unlikely(busiest == this_rq)) {
+ WARN_ON(1);
+ goto out_balanced;
+ }
+
+ nr_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. nr_moved simply stays zero, so it is
+ * correctly treated as an imbalance.
+ */
+ double_lock_balance(this_rq, busiest);
+ nr_moved = move_tasks(this_rq, this_cpu, busiest,
+ imbalance, sd, idle);
+ spin_unlock(&busiest->lock);
+ }
+ spin_unlock(&this_rq->lock);
+
+ if (!nr_moved) {
+ sd->nr_balance_failed++;
+
+ if (unlikely(sd->nr_balance_failed > sd->cache_nice_tries+2)) {
+ int wake = 0;
+
+ spin_lock(&busiest->lock);
+ if (!busiest->active_balance) {
+ busiest->active_balance = 1;
+ busiest->push_cpu = this_cpu;
+ wake = 1;
+ }
+ spin_unlock(&busiest->lock);
+ if (wake)
+ wake_up_process(busiest->migration_thread);
+
+ /*
+ * We've kicked active balancing, reset the failure
+ * counter.
+ */
+ sd->nr_balance_failed = sd->cache_nice_tries;
+ }
+ } else
+ sd->nr_balance_failed = 0;
+
+ /* We were unbalanced, so reset the balancing interval */
+ sd->balance_interval = sd->min_interval;
+
+ return nr_moved;
+
+out_balanced:
+ spin_unlock(&this_rq->lock);
+
+ /* tune up the balancing interval */
+ if (sd->balance_interval < sd->max_interval)
+ sd->balance_interval *= 2;
+
+ return 0;
+}
+
+/*
+ * 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 (NEWLY_IDLE).
+ * this_rq is locked.
+ */
+static int load_balance_newidle(int this_cpu, runqueue_t *this_rq,
+ struct sched_domain *sd)
+{
+ struct sched_group *group;
+ runqueue_t *busiest = NULL;
+ unsigned long imbalance;
+ int nr_moved = 0;
+
+ group = find_busiest_group(sd, this_cpu, &imbalance, NEWLY_IDLE);
+ if (!group)
+ goto out;
+
+ busiest = find_busiest_queue(group);
+ if (!busiest || busiest == this_rq)
+ goto out;
+
+ /* Attempt to move tasks */
+ double_lock_balance(this_rq, busiest);
+
+ nr_moved = move_tasks(this_rq, this_cpu, busiest,
+ imbalance, sd, NEWLY_IDLE);
+
+ spin_unlock(&busiest->lock);
+
+out:
+ return nr_moved;
+}
+
+/*
+ * idle_balance is called by schedule() if this_cpu is about to become
+ * idle. Attempts to pull tasks from other CPUs.
+ */
+static inline void idle_balance(int this_cpu, runqueue_t *this_rq)
+{
+ struct sched_domain *sd;
+
+ for_each_domain(this_cpu, sd) {
+ if (sd->flags & SD_BALANCE_NEWIDLE) {
+ if (load_balance_newidle(this_cpu, this_rq, sd)) {
+ /* We've pulled tasks over so stop searching */
+ break;
+ }
+ }
+ }
+}
+
+/*
+ * active_load_balance is run by migration threads. It pushes a running
+ * task off the cpu. It can be required to correctly have at least 1 task
+ * running on each physical CPU where possible, and not have a physical /
+ * logical imbalance.
+ *
+ * Called with busiest locked.
+ */
+static void active_load_balance(runqueue_t *busiest, int busiest_cpu)
+{
+ struct sched_domain *sd;
+ struct sched_group *group, *busy_group;
+ int i;
+
+ if (busiest->nr_running <= 1)
+ return;
+
+ for_each_domain(busiest_cpu, sd)
+ if (cpu_isset(busiest->push_cpu, sd->span))
+ break;
+ if (!sd) {
+ WARN_ON(1);
+ return;
}
- head = array->queue + idx;
- curr = head->prev;
-skip_queue:
- tmp = list_entry(curr, task_t, run_list);
+ group = sd->groups;
+ while (!cpu_isset(busiest_cpu, group->cpumask))
+ group = group->next;
+ busy_group = group;
- curr = curr->prev;
+ group = sd->groups;
+ do {
+ cpumask_t tmp;
+ runqueue_t *rq;
+ int push_cpu = 0;
- if (!can_migrate_task(tmp, busiest, this_cpu, idle)) {
- if (curr != head)
- goto skip_queue;
- idx++;
- goto skip_bitmap;
- }
- pull_task(busiest, array, tmp, this_rq, this_cpu);
+ if (group == busy_group)
+ goto next_group;
- /* Only migrate one task if we are idle */
- if (!idle && --imbalance) {
- if (curr != head)
- goto skip_queue;
- idx++;
- goto skip_bitmap;
- }
-out_unlock:
- spin_unlock(&busiest->lock);
-out:
- ;
+ cpus_and(tmp, group->cpumask, cpu_online_map);
+ if (!cpus_weight(tmp))
+ goto next_group;
+
+ for_each_cpu_mask(i, tmp) {
+ if (!idle_cpu(i))
+ goto next_group;
+ push_cpu = i;
+ }
+
+ rq = cpu_rq(push_cpu);
+
+ /*
+ * This condition is "impossible", but since load
+ * balancing is inherently a bit racy and statistical,
+ * it can trigger.. Reported by Bjorn Helgaas on a
+ * 128-cpu setup.
+ */
+ if (unlikely(busiest == rq))
+ goto next_group;
+ double_lock_balance(busiest, rq);
+ move_tasks(rq, push_cpu, busiest, 1, sd, IDLE);
+ spin_unlock(&rq->lock);
+next_group:
+ group = group->next;
+ } while (group != sd->groups);
}
/*
- * One of the idle_cpu_tick() and busy_cpu_tick() functions will
- * get called every timer tick, on every CPU. Our balancing action
- * frequency and balancing agressivity depends on whether the CPU is
- * idle or not.
+ * rebalance_tick will get called every timer tick, on every CPU.
*
- * busy-rebalance every 200 msecs. idle-rebalance every 1 msec. (or on
- * systems with HZ=100, every 10 msecs.)
+ * It checks each scheduling domain to see if it is due to be balanced,
+ * and initiates a balancing operation if so.
*
- * On NUMA, do a node-rebalance every 400 msecs.
+ * Balancing parameters are set up in arch_init_sched_domains.
*/
-#define IDLE_REBALANCE_TICK (HZ/1000 ?: 1)
-#define BUSY_REBALANCE_TICK (HZ/5 ?: 1)
-#define IDLE_NODE_REBALANCE_TICK (IDLE_REBALANCE_TICK * 5)
-#define BUSY_NODE_REBALANCE_TICK (BUSY_REBALANCE_TICK * 2)
-
-#ifdef CONFIG_NUMA
-static void balance_node(runqueue_t *this_rq, int idle, int this_cpu)
-{
- int node = find_busiest_node(cpu_to_node(this_cpu));
- if (node >= 0) {
- cpumask_t cpumask = node_to_cpumask(node);
- cpu_set(this_cpu, cpumask);
- spin_lock(&this_rq->lock);
- load_balance(this_rq, idle, cpumask);
- spin_unlock(&this_rq->lock);
- }
-}
-#endif
+/* Don't have all balancing operations going off at once */
+#define CPU_OFFSET(cpu) (HZ * cpu / NR_CPUS)
-static void rebalance_tick(runqueue_t *this_rq, int idle)
+static void rebalance_tick(int this_cpu, runqueue_t *this_rq,
+ enum idle_type idle)
{
-#ifdef CONFIG_NUMA
- int this_cpu = smp_processor_id();
-#endif
- unsigned long j = jiffies;
+ unsigned long old_load, this_load;
+ unsigned long j = jiffies + CPU_OFFSET(this_cpu);
+ struct sched_domain *sd;
+ /* Update our load */
+ old_load = this_rq->cpu_load;
+ this_load = this_rq->nr_running * SCHED_LOAD_SCALE;
/*
- * First do inter-node rebalancing, then intra-node rebalancing,
- * if both events happen in the same tick. The inter-node
- * rebalancing does not necessarily have to create a perfect
- * balance within the node, since we load-balance the most loaded
- * node with the current CPU. (ie. other CPUs in the local node
- * are not balanced.)
+ * Round up the averaging division if load is increasing. This
+ * prevents us from getting stuck on 9 if the load is 10, for
+ * example.
*/
- if (idle) {
-#ifdef CONFIG_NUMA
- if (!(j % IDLE_NODE_REBALANCE_TICK))
- balance_node(this_rq, idle, this_cpu);
-#endif
- if (!(j % IDLE_REBALANCE_TICK)) {
- spin_lock(&this_rq->lock);
- load_balance(this_rq, idle, cpu_to_node_mask(this_cpu));
- spin_unlock(&this_rq->lock);
+ if (this_load > old_load)
+ old_load++;
+ this_rq->cpu_load = (old_load + this_load) / 2;
+
+ for_each_domain(this_cpu, sd) {
+ unsigned long interval = sd->balance_interval;
+
+ if (idle != IDLE)
+ interval *= sd->busy_factor;
+
+ /* scale ms to jiffies */
+ interval = msecs_to_jiffies(interval);
+ if (unlikely(!interval))
+ interval = 1;
+
+ if (j - sd->last_balance >= interval) {
+ if (load_balance(this_cpu, this_rq, sd, idle)) {
+ /* We've pulled tasks over so no longer idle */
+ idle = NOT_IDLE;
+ }
+ sd->last_balance += interval;
}
- return;
- }
-#ifdef CONFIG_NUMA
- if (!(j % BUSY_NODE_REBALANCE_TICK))
- balance_node(this_rq, idle, this_cpu);
-#endif
- if (!(j % BUSY_REBALANCE_TICK)) {
- spin_lock(&this_rq->lock);
- load_balance(this_rq, idle, cpu_to_node_mask(this_cpu));
- spin_unlock(&this_rq->lock);
}
}
#else
/*
* on UP we do not need to balance between CPUs:
*/
-static inline void rebalance_tick(runqueue_t *this_rq, int idle)
+static inline void rebalance_tick(int cpu, runqueue_t *rq, enum idle_type idle)
+{
+}
+static inline void idle_balance(int cpu, runqueue_t *rq)
{
}
#endif
+static inline int wake_priority_sleeper(runqueue_t *rq)
+{
+#ifdef CONFIG_SCHED_SMT
+ /*
+ * If an SMT sibling task has been put to sleep for priority
+ * reasons reschedule the idle task to see if it can now run.
+ */
+ if (rq->nr_running) {
+ resched_task(rq->idle);
+ return 1;
+ }
+#endif
+ return 0;
+}
+
DEFINE_PER_CPU(struct kernel_stat, kstat);
EXPORT_PER_CPU_SYMBOL(kstat);
cpustat->iowait += sys_ticks;
else
cpustat->idle += sys_ticks;
- rebalance_tick(rq, 1);
+ if (wake_priority_sleeper(rq))
+ goto out;
+ rebalance_tick(cpu, rq, IDLE);
return;
}
if (TASK_NICE(p) > 0)
out_unlock:
spin_unlock(&rq->lock);
out:
- rebalance_tick(rq, 0);
+ rebalance_tick(cpu, rq, NOT_IDLE);
+}
+
+#ifdef CONFIG_SCHED_SMT
+static inline void wake_sleeping_dependent(int cpu, runqueue_t *rq)
+{
+ int i;
+ struct sched_domain *sd = rq->sd;
+ cpumask_t sibling_map;
+
+ if (!(sd->flags & SD_SHARE_CPUPOWER))
+ return;
+
+ cpus_and(sibling_map, sd->span, cpu_online_map);
+ for_each_cpu_mask(i, sibling_map) {
+ runqueue_t *smt_rq;
+
+ if (i == cpu)
+ continue;
+
+ smt_rq = cpu_rq(i);
+
+ /*
+ * If an SMT sibling task is sleeping due to priority
+ * reasons wake it up now.
+ */
+ if (smt_rq->curr == smt_rq->idle && smt_rq->nr_running)
+ resched_task(smt_rq->idle);
+ }
+}
+
+static inline int dependent_sleeper(int cpu, runqueue_t *rq, task_t *p)
+{
+ struct sched_domain *sd = rq->sd;
+ cpumask_t sibling_map;
+ int ret = 0, i;
+
+ if (!(sd->flags & SD_SHARE_CPUPOWER))
+ return 0;
+
+ cpus_and(sibling_map, sd->span, cpu_online_map);
+ for_each_cpu_mask(i, sibling_map) {
+ runqueue_t *smt_rq;
+ task_t *smt_curr;
+
+ if (i == cpu)
+ continue;
+
+ smt_rq = cpu_rq(i);
+ smt_curr = smt_rq->curr;
+
+ /*
+ * If a user task with lower static priority than the
+ * running task on the SMT sibling is trying to schedule,
+ * delay it till there is proportionately less timeslice
+ * left of the sibling task to prevent a lower priority
+ * task from using an unfair proportion of the
+ * physical cpu's resources. -ck
+ */
+ if (((smt_curr->time_slice * (100 - sd->per_cpu_gain) / 100) >
+ task_timeslice(p) || rt_task(smt_curr)) &&
+ p->mm && smt_curr->mm && !rt_task(p))
+ ret = 1;
+
+ /*
+ * Reschedule a lower priority task on the SMT sibling,
+ * or wake it up if it has been put to sleep for priority
+ * reasons.
+ */
+ if ((((p->time_slice * (100 - sd->per_cpu_gain) / 100) >
+ task_timeslice(smt_curr) || rt_task(p)) &&
+ smt_curr->mm && p->mm && !rt_task(smt_curr)) ||
+ (smt_curr == smt_rq->idle && smt_rq->nr_running))
+ resched_task(smt_curr);
+ }
+ return ret;
}
+#else
+static inline void wake_sleeping_dependent(int cpu, runqueue_t *rq)
+{
+}
+
+static inline int dependent_sleeper(int cpu, runqueue_t *rq, task_t *p)
+{
+ return 0;
+}
+#endif
/*
* schedule() is the main scheduler function.
struct vx_info *vxi;
int maxidle = -HZ;
#endif
- int idx;
+ int cpu, idx;
/*
* Test if we are atomic. Since do_exit() needs to call into
pick_next:
#endif
+ cpu = smp_processor_id();
if (unlikely(!rq->nr_running)) {
-#ifdef CONFIG_SMP
- load_balance(rq, 1, cpu_to_node_mask(smp_processor_id()));
-#endif
+ idle_balance(cpu, rq);
if (!rq->nr_running) {
next = rq->idle;
rq->expired_timestamp = 0;
+ wake_sleeping_dependent(cpu, rq);
goto switch_tasks;
}
}
queue = array->queue + idx;
next = list_entry(queue->next, task_t, run_list);
+ if (dependent_sleeper(cpu, rq, next)) {
+ next = rq->idle;
+ goto switch_tasks;
+ }
+
#ifdef CONFIG_VSERVER_HARDCPU
vxi = next->vx_info;
if (vxi && __vx_flags(vxi->vx_flags,
EXPORT_SYMBOL(preempt_schedule);
#endif /* CONFIG_PREEMPT */
-int default_wake_function(wait_queue_t *curr, unsigned mode, int sync)
+int default_wake_function(wait_queue_t *curr, unsigned mode, int sync, void *key)
{
task_t *p = curr->task;
return try_to_wake_up(p, mode, sync);
* zero in this (rare) case, and we handle it by continuing to scan the queue.
*/
static void __wake_up_common(wait_queue_head_t *q, unsigned int mode,
- int nr_exclusive, int sync)
+ int nr_exclusive, int sync, void *key)
{
struct list_head *tmp, *next;
unsigned flags;
curr = list_entry(tmp, wait_queue_t, task_list);
flags = curr->flags;
- if (curr->func(curr, mode, sync) &&
+ if (curr->func(curr, mode, sync, key) &&
(flags & WQ_FLAG_EXCLUSIVE) &&
!--nr_exclusive)
break;
* @mode: which threads
* @nr_exclusive: how many wake-one or wake-many threads to wake up
*/
-void fastcall __wake_up(wait_queue_head_t *q, unsigned int mode, int nr_exclusive)
+void fastcall __wake_up(wait_queue_head_t *q, unsigned int mode,
+ int nr_exclusive, void *key)
{
unsigned long flags;
spin_lock_irqsave(&q->lock, flags);
- __wake_up_common(q, mode, nr_exclusive, 0);
+ __wake_up_common(q, mode, nr_exclusive, 0, key);
spin_unlock_irqrestore(&q->lock, flags);
}
*/
void fastcall __wake_up_locked(wait_queue_head_t *q, unsigned int mode)
{
- __wake_up_common(q, mode, 1, 0);
+ __wake_up_common(q, mode, 1, 0, NULL);
}
/**
void fastcall __wake_up_sync(wait_queue_head_t *q, unsigned int mode, int nr_exclusive)
{
unsigned long flags;
+ int sync = 1;
if (unlikely(!q))
return;
+ if (unlikely(!nr_exclusive))
+ sync = 0;
+
spin_lock_irqsave(&q->lock, flags);
- if (likely(nr_exclusive))
- __wake_up_common(q, mode, nr_exclusive, 1);
- else
- __wake_up_common(q, mode, nr_exclusive, 0);
+ __wake_up_common(q, mode, nr_exclusive, sync, NULL);
spin_unlock_irqrestore(&q->lock, flags);
}
EXPORT_SYMBOL_GPL(__wake_up_sync); /* For internal use only */
spin_lock_irqsave(&x->wait.lock, flags);
x->done++;
__wake_up_common(&x->wait, TASK_UNINTERRUPTIBLE | TASK_INTERRUPTIBLE,
- 1, 0);
+ 1, 0, NULL);
spin_unlock_irqrestore(&x->wait.lock, flags);
}
EXPORT_SYMBOL(complete);
spin_lock_irqsave(&x->wait.lock, flags);
x->done += UINT_MAX/2;
__wake_up_common(&x->wait, TASK_UNINTERRUPTIBLE | TASK_INTERRUPTIBLE,
- 0, 0);
+ 0, 0, NULL);
spin_unlock_irqrestore(&x->wait.lock, flags);
}
EXPORT_SYMBOL(complete_all);
EXPORT_SYMBOL(set_user_nice);
-#ifndef __alpha__
+#ifdef __ARCH_WANT_SYS_NICE
/*
* sys_nice - change the priority of the current process.
if (task_running(rq, p)) {
if (p->prio > oldprio)
resched_task(rq->curr);
- } else if (p->prio < rq->curr->prio)
+ } else if (TASK_PREEMPTS_CURR(p, rq))
resched_task(rq->curr);
}
if (len < real_len)
return -EINVAL;
+ lock_cpu_hotplug();
read_lock(&tasklist_lock);
retval = -ESRCH;
out_unlock:
read_unlock(&tasklist_lock);
+ unlock_cpu_hotplug();
if (retval)
return retval;
if (copy_to_user(user_mask_ptr, &mask, real_len))
{
runqueue_t *rq = this_rq_lock();
prio_array_t *array = current->array;
+ prio_array_t *target = rq->expired;
/*
* We implement yielding by moving the task into the expired
* (special rule: RT tasks will just roundrobin in the active
* array.)
*/
- if (likely(!rt_task(current))) {
- dequeue_task(current, array);
- enqueue_task(current, rq->expired);
- } else {
- list_del(¤t->run_list);
- list_add_tail(¤t->run_list, array->queue + current->prio);
- }
+ if (unlikely(rt_task(current)))
+ target = rq->active;
+
+ dequeue_task(current, array);
+ enqueue_task(current, target);
+
/*
* Since we are going to call schedule() anyway, there's
- * no need to preempt:
+ * no need to preempt or enable interrupts:
*/
_raw_spin_unlock(&rq->lock);
preempt_enable_no_resched();
read_unlock(&tasklist_lock);
}
-void __init init_idle(task_t *idle, int cpu)
+void __devinit init_idle(task_t *idle, int cpu)
{
runqueue_t *idle_rq = cpu_rq(cpu), *rq = cpu_rq(task_cpu(idle));
unsigned long flags;
}
/*
- * In a system that switches off the HZ timer idle_cpu_mask
+ * In a system that switches off the HZ timer nohz_cpu_mask
* indicates which cpus entered this state. This is used
* in the rcu update to wait only for active cpus. For system
- * which do not switch off the HZ timer idle_cpu_mask should
+ * which do not switch off the HZ timer nohz_cpu_mask should
* always be CPU_MASK_NONE.
*/
-cpumask_t idle_cpu_mask = CPU_MASK_NONE;
+cpumask_t nohz_cpu_mask = CPU_MASK_NONE;
#ifdef CONFIG_SMP
/*
goto out;
}
- if (__set_cpus_allowed(p, new_mask, &req)) {
+ p->cpus_allowed = new_mask;
+ /* Can the task run on the task's current CPU? If so, we're done */
+ if (cpu_isset(task_cpu(p), new_mask))
+ goto out;
+
+ if (migrate_task(p, any_online_cpu(new_mask), &req)) {
/* Need help from migration thread: drop lock and wait. */
task_rq_unlock(rq, &flags);
wake_up_process(rq->migration_thread);
EXPORT_SYMBOL_GPL(set_cpus_allowed);
-/* Move (not current) task off this cpu, onto dest cpu. */
-static void move_task_away(struct task_struct *p, int dest_cpu)
+/*
+ * Move (not current) task off this cpu, onto dest cpu. We're doing
+ * this because either it can't run here any more (set_cpus_allowed()
+ * away from this CPU, or CPU going down), or because we're
+ * attempting to rebalance this task on exec (sched_balance_exec).
+ *
+ * So we race with normal scheduler movements, but that's OK, as long
+ * as the task is no longer on this CPU.
+ */
+static void __migrate_task(struct task_struct *p, int src_cpu, int dest_cpu)
{
- runqueue_t *rq_dest;
+ runqueue_t *rq_dest, *rq_src;
+
+ if (unlikely(cpu_is_offline(dest_cpu)))
+ return;
+ rq_src = cpu_rq(src_cpu);
rq_dest = cpu_rq(dest_cpu);
- double_rq_lock(this_rq(), rq_dest);
- if (task_cpu(p) != smp_processor_id())
- goto out; /* Already moved */
+ double_rq_lock(rq_src, rq_dest);
+ /* Already moved. */
+ if (task_cpu(p) != src_cpu)
+ goto out;
+ /* Affinity changed (again). */
+ if (!cpu_isset(dest_cpu, p->cpus_allowed))
+ goto out;
set_task_cpu(p, dest_cpu);
if (p->array) {
- deactivate_task(p, this_rq());
- activate_task(p, rq_dest);
- if (p->prio < rq_dest->curr->prio)
+ /*
+ * Sync timestamp with rq_dest's before activating.
+ * The same thing could be achieved by doing this step
+ * afterwards, and pretending it was a local activate.
+ * This way is cleaner and logically correct.
+ */
+ p->timestamp = p->timestamp - rq_src->timestamp_last_tick
+ + rq_dest->timestamp_last_tick;
+ deactivate_task(p, rq_src);
+ activate_task(p, rq_dest, 0);
+ if (TASK_PREEMPTS_CURR(p, rq_dest))
resched_task(rq_dest->curr);
}
- p->timestamp = rq_dest->timestamp_last_tick;
out:
- double_rq_unlock(this_rq(), rq_dest);
+ double_rq_unlock(rq_src, rq_dest);
}
/*
rq = cpu_rq(cpu);
BUG_ON(rq->migration_thread != current);
+ set_current_state(TASK_INTERRUPTIBLE);
while (!kthread_should_stop()) {
struct list_head *head;
migration_req_t *req;
refrigerator(PF_FREEZE);
spin_lock_irq(&rq->lock);
+
+ if (cpu_is_offline(cpu)) {
+ spin_unlock_irq(&rq->lock);
+ goto wait_to_die;
+ }
+
+ if (rq->active_balance) {
+ active_load_balance(rq, cpu);
+ rq->active_balance = 0;
+ }
+
head = &rq->migration_queue;
- current->state = TASK_INTERRUPTIBLE;
+
if (list_empty(head)) {
spin_unlock_irq(&rq->lock);
schedule();
+ set_current_state(TASK_INTERRUPTIBLE);
continue;
}
req = list_entry(head->next, migration_req_t, list);
list_del_init(head->next);
- spin_unlock(&rq->lock);
- move_task_away(req->task,
- any_online_cpu(req->task->cpus_allowed));
- local_irq_enable();
+ if (req->type == REQ_MOVE_TASK) {
+ spin_unlock(&rq->lock);
+ __migrate_task(req->task, smp_processor_id(),
+ req->dest_cpu);
+ local_irq_enable();
+ } else if (req->type == REQ_SET_DOMAIN) {
+ rq->sd = req->sd;
+ spin_unlock_irq(&rq->lock);
+ } else {
+ spin_unlock_irq(&rq->lock);
+ WARN_ON(1);
+ }
+
complete(&req->done);
}
+ __set_current_state(TASK_RUNNING);
+ return 0;
+
+wait_to_die:
+ /* Wait for kthread_stop */
+ set_current_state(TASK_INTERRUPTIBLE);
+ while (!kthread_should_stop()) {
+ schedule();
+ set_current_state(TASK_INTERRUPTIBLE);
+ }
+ __set_current_state(TASK_RUNNING);
return 0;
}
#ifdef CONFIG_HOTPLUG_CPU
-/* migrate_all_tasks - function to migrate all the tasks from the
- * current cpu caller must have already scheduled this to the target
- * cpu via set_cpus_allowed. Machine is stopped. */
-void migrate_all_tasks(void)
+/* migrate_all_tasks - function to migrate all tasks from the dead cpu. */
+static void migrate_all_tasks(int src_cpu)
{
struct task_struct *tsk, *t;
- int dest_cpu, src_cpu;
+ int dest_cpu;
unsigned int node;
- /* We're nailed to this CPU. */
- src_cpu = smp_processor_id();
-
- /* Not required, but here for neatness. */
- write_lock(&tasklist_lock);
+ write_lock_irq(&tasklist_lock);
/* watch out for per node tasks, let's stay on this node */
node = cpu_to_node(src_cpu);
tsk->pid, tsk->comm, src_cpu);
}
- move_task_away(tsk, dest_cpu);
+ __migrate_task(tsk, src_cpu, dest_cpu);
} while_each_thread(t, tsk);
- write_unlock(&tasklist_lock);
+ write_unlock_irq(&tasklist_lock);
+}
+
+/* Schedules idle task to be the next runnable task on current CPU.
+ * It does so by boosting its priority to highest possible and adding it to
+ * the _front_ of runqueue. Used by CPU offline code.
+ */
+void sched_idle_next(void)
+{
+ int cpu = smp_processor_id();
+ runqueue_t *rq = this_rq();
+ struct task_struct *p = rq->idle;
+ unsigned long flags;
+
+ /* cpu has to be offline */
+ BUG_ON(cpu_online(cpu));
+
+ /* Strictly not necessary since rest of the CPUs are stopped by now
+ * and interrupts disabled on current cpu.
+ */
+ spin_lock_irqsave(&rq->lock, flags);
+
+ __setscheduler(p, SCHED_FIFO, MAX_RT_PRIO-1);
+ /* Add idle task to _front_ of it's priority queue */
+ __activate_idle_task(p, rq);
+
+ spin_unlock_irqrestore(&rq->lock, flags);
}
#endif /* CONFIG_HOTPLUG_CPU */
case CPU_UP_CANCELED:
/* Unbind it from offline cpu so it can run. Fall thru. */
kthread_bind(cpu_rq(cpu)->migration_thread,smp_processor_id());
- case CPU_DEAD:
kthread_stop(cpu_rq(cpu)->migration_thread);
cpu_rq(cpu)->migration_thread = NULL;
- BUG_ON(cpu_rq(cpu)->nr_running != 0);
+ break;
+ case CPU_DEAD:
+ migrate_all_tasks(cpu);
+ rq = cpu_rq(cpu);
+ kthread_stop(rq->migration_thread);
+ rq->migration_thread = NULL;
+ /* Idle task back to normal (off runqueue, low prio) */
+ rq = task_rq_lock(rq->idle, &flags);
+ deactivate_task(rq->idle, rq);
+ rq->idle->static_prio = MAX_PRIO;
+ __setscheduler(rq->idle, SCHED_NORMAL, 0);
+ task_rq_unlock(rq, &flags);
+ BUG_ON(rq->nr_running != 0);
+
+ /* No need to migrate the tasks: it was best-effort if
+ * they didn't do lock_cpu_hotplug(). Just wake up
+ * the requestors. */
+ spin_lock_irq(&rq->lock);
+ while (!list_empty(&rq->migration_queue)) {
+ migration_req_t *req;
+ req = list_entry(rq->migration_queue.next,
+ migration_req_t, list);
+ BUG_ON(req->type != REQ_MOVE_TASK);
+ list_del_init(&req->list);
+ complete(&req->done);
+ }
+ spin_unlock_irq(&rq->lock);
break;
#endif
}
return NOTIFY_OK;
}
+/* Register at highest priority so that task migration (migrate_all_tasks)
+ * happens before everything else.
+ */
static struct notifier_block __devinitdata migration_notifier = {
.notifier_call = migration_call,
+ .priority = 10
};
int __init migration_init(void)
spinlock_t kernel_flag __cacheline_aligned_in_smp = SPIN_LOCK_UNLOCKED;
EXPORT_SYMBOL(kernel_flag);
+#ifdef CONFIG_SMP
+/* Attach the domain 'sd' to 'cpu' as its base domain */
+void cpu_attach_domain(struct sched_domain *sd, int cpu)
+{
+ migration_req_t req;
+ unsigned long flags;
+ runqueue_t *rq = cpu_rq(cpu);
+ int local = 1;
+
+ lock_cpu_hotplug();
+
+ spin_lock_irqsave(&rq->lock, flags);
+
+ if (cpu == smp_processor_id() || !cpu_online(cpu)) {
+ rq->sd = sd;
+ } else {
+ init_completion(&req.done);
+ req.type = REQ_SET_DOMAIN;
+ req.sd = sd;
+ list_add(&req.list, &rq->migration_queue);
+ local = 0;
+ }
+
+ spin_unlock_irqrestore(&rq->lock, flags);
+
+ if (!local) {
+ wake_up_process(rq->migration_thread);
+ wait_for_completion(&req.done);
+ }
+
+ unlock_cpu_hotplug();
+}
+
+#ifdef ARCH_HAS_SCHED_DOMAIN
+extern void __init arch_init_sched_domains(void);
+#else
+static struct sched_group sched_group_cpus[NR_CPUS];
+static DEFINE_PER_CPU(struct sched_domain, cpu_domains);
+#ifdef CONFIG_NUMA
+static struct sched_group sched_group_nodes[MAX_NUMNODES];
+static DEFINE_PER_CPU(struct sched_domain, node_domains);
+static void __init arch_init_sched_domains(void)
+{
+ int i;
+ struct sched_group *first_node = NULL, *last_node = NULL;
+
+ /* Set up domains */
+ for_each_cpu(i) {
+ int node = cpu_to_node(i);
+ cpumask_t nodemask = node_to_cpumask(node);
+ struct sched_domain *node_sd = &per_cpu(node_domains, i);
+ struct sched_domain *cpu_sd = &per_cpu(cpu_domains, i);
+
+ *node_sd = SD_NODE_INIT;
+ node_sd->span = cpu_possible_map;
+ node_sd->groups = &sched_group_nodes[cpu_to_node(i)];
+
+ *cpu_sd = SD_CPU_INIT;
+ cpus_and(cpu_sd->span, nodemask, cpu_possible_map);
+ cpu_sd->groups = &sched_group_cpus[i];
+ cpu_sd->parent = node_sd;
+ }
+
+ /* Set up groups */
+ for (i = 0; i < MAX_NUMNODES; i++) {
+ cpumask_t tmp = node_to_cpumask(i);
+ cpumask_t nodemask;
+ struct sched_group *first_cpu = NULL, *last_cpu = NULL;
+ struct sched_group *node = &sched_group_nodes[i];
+ int j;
+
+ cpus_and(nodemask, tmp, cpu_possible_map);
+
+ if (cpus_empty(nodemask))
+ continue;
+
+ node->cpumask = nodemask;
+ node->cpu_power = SCHED_LOAD_SCALE * cpus_weight(node->cpumask);
+
+ for_each_cpu_mask(j, node->cpumask) {
+ struct sched_group *cpu = &sched_group_cpus[j];
+
+ cpus_clear(cpu->cpumask);
+ cpu_set(j, cpu->cpumask);
+ cpu->cpu_power = SCHED_LOAD_SCALE;
+
+ if (!first_cpu)
+ first_cpu = cpu;
+ if (last_cpu)
+ last_cpu->next = cpu;
+ last_cpu = cpu;
+ }
+ last_cpu->next = first_cpu;
+
+ if (!first_node)
+ first_node = node;
+ if (last_node)
+ last_node->next = node;
+ last_node = node;
+ }
+ last_node->next = first_node;
+
+ mb();
+ for_each_cpu(i) {
+ struct sched_domain *cpu_sd = &per_cpu(cpu_domains, i);
+ cpu_attach_domain(cpu_sd, i);
+ }
+}
+
+#else /* !CONFIG_NUMA */
+static void __init arch_init_sched_domains(void)
+{
+ int i;
+ struct sched_group *first_cpu = NULL, *last_cpu = NULL;
+
+ /* Set up domains */
+ for_each_cpu(i) {
+ struct sched_domain *cpu_sd = &per_cpu(cpu_domains, i);
+
+ *cpu_sd = SD_CPU_INIT;
+ cpu_sd->span = cpu_possible_map;
+ cpu_sd->groups = &sched_group_cpus[i];
+ }
+
+ /* Set up CPU groups */
+ for_each_cpu_mask(i, cpu_possible_map) {
+ struct sched_group *cpu = &sched_group_cpus[i];
+
+ cpus_clear(cpu->cpumask);
+ cpu_set(i, cpu->cpumask);
+ cpu->cpu_power = SCHED_LOAD_SCALE;
+
+ if (!first_cpu)
+ first_cpu = cpu;
+ if (last_cpu)
+ last_cpu->next = cpu;
+ last_cpu = cpu;
+ }
+ last_cpu->next = first_cpu;
+
+ mb(); /* domains were modified outside the lock */
+ for_each_cpu(i) {
+ struct sched_domain *cpu_sd = &per_cpu(cpu_domains, i);
+ cpu_attach_domain(cpu_sd, i);
+ }
+}
+
+#endif /* CONFIG_NUMA */
+#endif /* ARCH_HAS_SCHED_DOMAIN */
+
+#define SCHED_DOMAIN_DEBUG
+#ifdef SCHED_DOMAIN_DEBUG
+void sched_domain_debug(void)
+{
+ int i;
+
+ for_each_cpu(i) {
+ runqueue_t *rq = cpu_rq(i);
+ struct sched_domain *sd;
+ int level = 0;
+
+ sd = rq->sd;
+
+ printk(KERN_DEBUG "CPU%d: %s\n",
+ i, (cpu_online(i) ? " online" : "offline"));
+
+ do {
+ int j;
+ char str[NR_CPUS];
+ struct sched_group *group = sd->groups;
+ cpumask_t groupmask, tmp;
+
+ cpumask_scnprintf(str, NR_CPUS, sd->span);
+ cpus_clear(groupmask);
+
+ printk(KERN_DEBUG);
+ for (j = 0; j < level + 1; j++)
+ printk(" ");
+ printk("domain %d: span %s\n", level, str);
+
+ if (!cpu_isset(i, sd->span))
+ printk(KERN_DEBUG "ERROR domain->span does not contain CPU%d\n", i);
+ if (!cpu_isset(i, group->cpumask))
+ printk(KERN_DEBUG "ERROR domain->groups does not contain CPU%d\n", i);
+ if (!group->cpu_power)
+ printk(KERN_DEBUG "ERROR domain->cpu_power not set\n");
+
+ printk(KERN_DEBUG);
+ for (j = 0; j < level + 2; j++)
+ printk(" ");
+ printk("groups:");
+ do {
+ if (!group) {
+ printk(" ERROR: NULL");
+ break;
+ }
+
+ if (!cpus_weight(group->cpumask))
+ printk(" ERROR empty group:");
+
+ cpus_and(tmp, groupmask, group->cpumask);
+ if (cpus_weight(tmp) > 0)
+ printk(" ERROR repeated CPUs:");
+
+ cpus_or(groupmask, groupmask, group->cpumask);
+
+ cpumask_scnprintf(str, NR_CPUS, group->cpumask);
+ printk(" %s", str);
+
+ group = group->next;
+ } while (group != sd->groups);
+ printk("\n");
+
+ if (!cpus_equal(sd->span, groupmask))
+ printk(KERN_DEBUG "ERROR groups don't span domain->span\n");
+
+ level++;
+ sd = sd->parent;
+
+ if (sd) {
+ cpus_and(tmp, groupmask, sd->span);
+ if (!cpus_equal(tmp, groupmask))
+ printk(KERN_DEBUG "ERROR parent span is not a superset of domain->span\n");
+ }
+
+ } while (sd);
+ }
+}
+#else
+#define sched_domain_debug() {}
+#endif
+
+void __init sched_init_smp(void)
+{
+ arch_init_sched_domains();
+ sched_domain_debug();
+}
+#else
+void __init sched_init_smp(void)
+{
+}
+#endif /* CONFIG_SMP */
+
+int in_sched_functions(unsigned long addr)
+{
+ /* Linker adds these: start and end of __sched functions */
+ extern char __sched_text_start[], __sched_text_end[];
+ return addr >= (unsigned long)__sched_text_start
+ && addr < (unsigned long)__sched_text_end;
+}
+
void __init sched_init(void)
{
runqueue_t *rq;
int i, j, k;
+#ifdef CONFIG_SMP
+ /* Set up an initial dummy domain for early boot */
+ static struct sched_domain sched_domain_init;
+ static struct sched_group sched_group_init;
+ cpumask_t cpu_mask_all = CPU_MASK_ALL;
+
+ memset(&sched_domain_init, 0, sizeof(struct sched_domain));
+ sched_domain_init.span = cpu_mask_all;
+ sched_domain_init.groups = &sched_group_init;
+ sched_domain_init.last_balance = jiffies;
+ sched_domain_init.balance_interval = INT_MAX; /* Don't balance */
+
+ memset(&sched_group_init, 0, sizeof(struct sched_group));
+ sched_group_init.cpumask = cpu_mask_all;
+ sched_group_init.next = &sched_group_init;
+ sched_group_init.cpu_power = SCHED_LOAD_SCALE;
+#endif
+
for (i = 0; i < NR_CPUS; i++) {
prio_array_t *array;
rq = cpu_rq(i);
+ spin_lock_init(&rq->lock);
rq->active = rq->arrays;
rq->expired = rq->arrays + 1;
rq->best_expired_prio = MAX_PRIO;
- spin_lock_init(&rq->lock);
+#ifdef CONFIG_SMP
+ rq->sd = &sched_domain_init;
+ rq->cpu_load = 0;
+ rq->active_balance = 0;
+ rq->push_cpu = 0;
+ rq->migration_thread = NULL;
INIT_LIST_HEAD(&rq->migration_queue);
+#endif
INIT_LIST_HEAD(&rq->hold_queue);
atomic_set(&rq->nr_iowait, 0);
- nr_running_init(rq);
for (j = 0; j < 2; j++) {
array = rq->arrays + j;
set_task_cpu(current, smp_processor_id());
wake_up_forked_process(current);
- init_timers();
-
/*
* The boot idle thread does lazy MMU switching as well:
*/
git://git.onelab.eu / linux-2.6.git / blobdiff