1 files changed, 654 insertions, 419 deletions

diff --git a/kernel/sched.c b/kernel/sched.c
index f12a0c8a7d98..5f2182d42241 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -166,7 +166,7 @@
 #define SCALE_PRIO(x, prio) \
         max(x * (MAX_PRIO - prio) / (MAX_USER_PRIO/2), MIN_TIMESLICE)
 
-static inline unsigned int task_timeslice(task_t *p)
+static unsigned int task_timeslice(task_t *p)
 {
         if (p->static_prio < NICE_TO_PRIO(0))
                 return SCALE_PRIO(DEF_TIMESLICE*4, p->static_prio);
@@ -206,7 +206,7 @@ struct runqueue {
          */
         unsigned long nr_running;
 #ifdef CONFIG_SMP
-        unsigned long cpu_load;
+        unsigned long cpu_load[3];
 #endif
         unsigned long long nr_switches;
 
@@ -260,23 +260,87 @@ struct runqueue {
 
 static DEFINE_PER_CPU(struct runqueue, runqueues);
 
+/*
+ * The domain tree (rq->sd) is protected by RCU's quiescent state transition.
+ * See detach_destroy_domains: synchronize_sched for details.
+ *
+ * The domain tree of any CPU may only be accessed from within
+ * preempt-disabled sections.
+ */
 #define for_each_domain(cpu, domain) \
-        for (domain = cpu_rq(cpu)->sd; domain; domain = domain->parent)
+for (domain = rcu_dereference(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)
 
-/*
- * Default context-switch locking:
- */
 #ifndef prepare_arch_switch
-# define prepare_arch_switch(rq, next)  do { } while (0)
-# define finish_arch_switch(rq, next)   spin_unlock_irq(&(rq)->lock)
-# define task_running(rq, p)            ((rq)->curr == (p))
+# define prepare_arch_switch(next)      do { } while (0)
+#endif
+#ifndef finish_arch_switch
+# define finish_arch_switch(prev)       do { } while (0)
 #endif
 
+#ifndef __ARCH_WANT_UNLOCKED_CTXSW
+static inline int task_running(runqueue_t *rq, task_t *p)
+{
+        return rq->curr == p;
+}
+
+static inline void prepare_lock_switch(runqueue_t *rq, task_t *next)
+{
+}
+
+static inline void finish_lock_switch(runqueue_t *rq, task_t *prev)
+{
+        spin_unlock_irq(&rq->lock);
+}
+
+#else /* __ARCH_WANT_UNLOCKED_CTXSW */
+static inline int task_running(runqueue_t *rq, task_t *p)
+{
+#ifdef CONFIG_SMP
+        return p->oncpu;
+#else
+        return rq->curr == p;
+#endif
+}
+
+static inline void prepare_lock_switch(runqueue_t *rq, task_t *next)
+{
+#ifdef CONFIG_SMP
+        /*
+         * We can optimise this out completely for !SMP, because the
+         * SMP rebalancing from interrupt is the only thing that cares
+         * here.
+         */
+        next->oncpu = 1;
+#endif
+#ifdef __ARCH_WANT_INTERRUPTS_ON_CTXSW
+        spin_unlock_irq(&rq->lock);
+#else
+        spin_unlock(&rq->lock);
+#endif
+}
+
+static inline void finish_lock_switch(runqueue_t *rq, task_t *prev)
+{
+#ifdef CONFIG_SMP
+        /*
+         * After ->oncpu is cleared, the task can be moved to a different CPU.
+         * We must ensure this doesn't happen until the switch is completely
+         * finished.
+         */
+        smp_wmb();
+        prev->oncpu = 0;
+#endif
+#ifndef __ARCH_WANT_INTERRUPTS_ON_CTXSW
+        local_irq_enable();
+#endif
+}
+#endif /* __ARCH_WANT_UNLOCKED_CTXSW */
+
 /*
  * 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
@@ -309,7 +373,7 @@ static inline void task_rq_unlock(runqueue_t *rq, unsigned long *flags)
  * bump this up when changing the output format or the meaning of an existing
  * format, so that tools can adapt (or abort)
  */
-#define SCHEDSTAT_VERSION 11
+#define SCHEDSTAT_VERSION 12
 
 static int show_schedstat(struct seq_file *seq, void *v)
 {
@@ -338,6 +402,7 @@ static int show_schedstat(struct seq_file *seq, void *v)
 
 #ifdef CONFIG_SMP
                 /* domain-specific stats */
+                preempt_disable();
                 for_each_domain(cpu, sd) {
                         enum idle_type itype;
                         char mask_str[NR_CPUS];
@@ -356,11 +421,13 @@ static int show_schedstat(struct seq_file *seq, void *v)
                                     sd->lb_nobusyq[itype],
                                     sd->lb_nobusyg[itype]);
                         }
-                        seq_printf(seq, " %lu %lu %lu %lu %lu %lu %lu %lu\n",
+                        seq_printf(seq, " %lu %lu %lu %lu %lu %lu %lu %lu %lu %lu %lu %lu\n",
                             sd->alb_cnt, sd->alb_failed, sd->alb_pushed,
-                            sd->sbe_pushed, sd->sbe_attempts,
+                            sd->sbe_cnt, sd->sbe_balanced, sd->sbe_pushed,
+                            sd->sbf_cnt, sd->sbf_balanced, sd->sbf_pushed,
                             sd->ttwu_wake_remote, sd->ttwu_move_affine, sd->ttwu_move_balance);
                 }
+                preempt_enable();
 #endif
         }
         return 0;
@@ -414,22 +481,6 @@ static inline runqueue_t *this_rq_lock(void)
         return rq;
 }
 
-#ifdef CONFIG_SCHED_SMT
-static int cpu_and_siblings_are_idle(int cpu)
-{
-        int sib;
-        for_each_cpu_mask(sib, cpu_sibling_map[cpu]) {
-                if (idle_cpu(sib))
-                        continue;
-                return 0;
-        }
-
-        return 1;
-}
-#else
-#define cpu_and_siblings_are_idle(A) idle_cpu(A)
-#endif
-
 #ifdef CONFIG_SCHEDSTATS
 /*
  * Called when a process is dequeued from the active array and given
@@ -622,7 +673,7 @@ static inline void __activate_idle_task(task_t *p, runqueue_t *rq)
         rq->nr_running++;
 }
 
-static void recalc_task_prio(task_t *p, unsigned long long now)
+static int recalc_task_prio(task_t *p, unsigned long long now)
 {
         /* Caller must always ensure 'now >= p->timestamp' */
         unsigned long long __sleep_time = now - p->timestamp;
@@ -681,7 +732,7 @@ static void recalc_task_prio(task_t *p, unsigned long long now)
                 }
         }
 
-        p->prio = effective_prio(p);
+        return effective_prio(p);
 }
 
 /*
@@ -704,7 +755,7 @@ static void activate_task(task_t *p, runqueue_t *rq, int local)
         }
 #endif
 
-        recalc_task_prio(p, now);
+        p->prio = recalc_task_prio(p, now);
 
         /*
          * This checks to make sure it's not an uninterruptible task
@@ -782,22 +833,12 @@ inline int task_curr(const task_t *p)
 }
 
 #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;
 
@@ -819,7 +860,6 @@ static int migrate_task(task_t *p, int dest_cpu, migration_req_t *req)
         }
 
         init_completion(&req->done);
-        req->type = REQ_MOVE_TASK;
         req->task = p;
         req->dest_cpu = dest_cpu;
         list_add(&req->list, &rq->migration_queue);
@@ -886,26 +926,154 @@ void kick_process(task_t *p)
  * We want to under-estimate the load of migration sources, to
  * balance conservatively.
  */
-static inline unsigned long source_load(int cpu)
+static inline unsigned long source_load(int cpu, int type)
 {
         runqueue_t *rq = cpu_rq(cpu);
         unsigned long load_now = rq->nr_running * SCHED_LOAD_SCALE;
+        if (type == 0)
+                return load_now;
 
-        return min(rq->cpu_load, load_now);
+        return min(rq->cpu_load[type-1], load_now);
 }
 
 /*
  * Return a high guess at the load of a migration-target cpu
  */
-static inline unsigned long target_load(int cpu)
+static inline unsigned long target_load(int cpu, int type)
 {
         runqueue_t *rq = cpu_rq(cpu);
         unsigned long load_now = rq->nr_running * SCHED_LOAD_SCALE;
+        if (type == 0)
+                return load_now;
 
-        return max(rq->cpu_load, load_now);
+        return max(rq->cpu_load[type-1], load_now);
 }
 
-#endif
+/*
+ * find_idlest_group finds and returns the least busy CPU group within the
+ * domain.
+ */
+static struct sched_group *
+find_idlest_group(struct sched_domain *sd, struct task_struct *p, int this_cpu)
+{
+        struct sched_group *idlest = NULL, *this = NULL, *group = sd->groups;
+        unsigned long min_load = ULONG_MAX, this_load = 0;
+        int load_idx = sd->forkexec_idx;
+        int imbalance = 100 + (sd->imbalance_pct-100)/2;
+
+        do {
+                unsigned long load, avg_load;
+                int local_group;
+                int i;
+
+                local_group = cpu_isset(this_cpu, group->cpumask);
+                /* XXX: put a cpus allowed check */
+
+                /* Tally up the load of all CPUs in the group */
+                avg_load = 0;
+
+                for_each_cpu_mask(i, group->cpumask) {
+                        /* Bias balancing toward cpus of our domain */
+                        if (local_group)
+                                load = source_load(i, load_idx);
+                        else
+                                load = target_load(i, load_idx);
+
+                        avg_load += load;
+                }
+
+                /* 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;
+                } else if (avg_load < min_load) {
+                        min_load = avg_load;
+                        idlest = group;
+                }
+                group = group->next;
+        } while (group != sd->groups);
+
+        if (!idlest || 100*this_load < imbalance*min_load)
+                return NULL;
+        return idlest;
+}
+
+/*
+ * find_idlest_queue - find the idlest runqueue among the cpus in group.
+ */
+static int find_idlest_cpu(struct sched_group *group, int this_cpu)
+{
+        unsigned long load, min_load = ULONG_MAX;
+        int idlest = -1;
+        int i;
+
+        for_each_cpu_mask(i, group->cpumask) {
+                load = source_load(i, 0);
+
+                if (load < min_load || (load == min_load && i == this_cpu)) {
+                        min_load = load;
+                        idlest = i;
+                }
+        }
+
+        return idlest;
+}
+
+/*
+ * sched_balance_self: balance the current task (running on cpu) in domains
+ * that have the 'flag' flag set. In practice, this is SD_BALANCE_FORK and
+ * SD_BALANCE_EXEC.
+ *
+ * Balance, ie. select the least loaded group.
+ *
+ * Returns the target CPU number, or the same CPU if no balancing is needed.
+ *
+ * preempt must be disabled.
+ */
+static int sched_balance_self(int cpu, int flag)
+{
+        struct task_struct *t = current;
+        struct sched_domain *tmp, *sd = NULL;
+
+        for_each_domain(cpu, tmp)
+                if (tmp->flags & flag)
+                        sd = tmp;
+
+        while (sd) {
+                cpumask_t span;
+                struct sched_group *group;
+                int new_cpu;
+                int weight;
+
+                span = sd->span;
+                group = find_idlest_group(sd, t, cpu);
+                if (!group)
+                        goto nextlevel;
+
+                new_cpu = find_idlest_cpu(group, cpu);
+                if (new_cpu == -1 || new_cpu == cpu)
+                        goto nextlevel;
+
+                /* Now try balancing at a lower domain level */
+                cpu = new_cpu;
+nextlevel:
+                sd = NULL;
+                weight = cpus_weight(span);
+                for_each_domain(cpu, tmp) {
+                        if (weight <= cpus_weight(tmp->span))
+                                break;
+                        if (tmp->flags & flag)
+                                sd = tmp;
+                }
+                /* while loop will break here if sd == NULL */
+        }
+
+        return cpu;
+}
+
+#endif /* CONFIG_SMP */
 
 /*
  * wake_idle() will wake a task on an idle cpu if task->cpu is
@@ -927,14 +1095,14 @@ static int wake_idle(int cpu, task_t *p)
 
         for_each_domain(cpu, sd) {
                 if (sd->flags & SD_WAKE_IDLE) {
-                        cpus_and(tmp, sd->span, cpu_online_map);
-                        cpus_and(tmp, tmp, p->cpus_allowed);
+                        cpus_and(tmp, sd->span, p->cpus_allowed);
                         for_each_cpu_mask(i, tmp) {
                                 if (idle_cpu(i))
                                         return i;
                         }
                 }
-                else break;
+                else
+                        break;
         }
         return cpu;
 }
@@ -967,7 +1135,7 @@ static int try_to_wake_up(task_t * p, unsigned int state, int sync)
         runqueue_t *rq;
 #ifdef CONFIG_SMP
         unsigned long load, this_load;
-        struct sched_domain *sd;
+        struct sched_domain *sd, *this_sd = NULL;
         int new_cpu;
 #endif
 
@@ -986,70 +1154,69 @@ static int try_to_wake_up(task_t * p, unsigned int state, int sync)
         if (unlikely(task_running(rq, p)))
                 goto out_activate;
 
-#ifdef CONFIG_SCHEDSTATS
+        new_cpu = cpu;
+
         schedstat_inc(rq, ttwu_cnt);
         if (cpu == this_cpu) {
                 schedstat_inc(rq, ttwu_local);
-        } else {
-                for_each_domain(this_cpu, sd) {
-                        if (cpu_isset(cpu, sd->span)) {
-                                schedstat_inc(sd, ttwu_wake_remote);
-                                break;
-                        }
+                goto out_set_cpu;
+        }
+
+        for_each_domain(this_cpu, sd) {
+                if (cpu_isset(cpu, sd->span)) {
+                        schedstat_inc(sd, ttwu_wake_remote);
+                        this_sd = sd;
+                        break;
                 }
         }
-#endif
 
-        new_cpu = cpu;
-        if (cpu == this_cpu || unlikely(!cpu_isset(this_cpu, p->cpus_allowed)))
+        if (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:
+         * Check for affine wakeup and passive balancing possibilities.
          */
-        if (sync)
-                this_load -= SCHED_LOAD_SCALE;
+        if (this_sd) {
+                int idx = this_sd->wake_idx;
+                unsigned int imbalance;
 
-        /* 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;
+                imbalance = 100 + (this_sd->imbalance_pct - 100) / 2;
 
-        new_cpu = this_cpu; /* Wake to this CPU if we can */
+                load = source_load(cpu, idx);
+                this_load = target_load(this_cpu, idx);
 
-        /*
-         * 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;
+                new_cpu = this_cpu; /* Wake to this CPU if we can */
 
-                if ((sd->flags & SD_WAKE_AFFINE) &&
-                                !task_hot(p, rq->timestamp_last_tick, sd)) {
+                if (this_sd->flags & SD_WAKE_AFFINE) {
+                        unsigned long tl = this_load;
                         /*
-                         * This domain has SD_WAKE_AFFINE and p is cache cold
-                         * in this domain.
+                         * If sync wakeup then subtract the (maximum possible)
+                         * effect of the currently running task from the load
+                         * of the current CPU:
                          */
-                        if (cpu_isset(cpu, sd->span)) {
-                                schedstat_inc(sd, ttwu_move_affine);
+                        if (sync)
+                                tl -= SCHED_LOAD_SCALE;
+
+                        if ((tl <= load &&
+                                tl + target_load(cpu, idx) <= SCHED_LOAD_SCALE) ||
+                                100*(tl + SCHED_LOAD_SCALE) <= imbalance*load) {
+                                /*
+                                 * This domain has SD_WAKE_AFFINE and
+                                 * p is cache cold in this domain, and
+                                 * there is no bad imbalance.
+                                 */
+                                schedstat_inc(this_sd, ttwu_move_affine);
                                 goto out_set_cpu;
                         }
-                } else if ((sd->flags & SD_WAKE_BALANCE) &&
-                                imbalance*this_load <= 100*load) {
-                        /*
-                         * This domain has SD_WAKE_BALANCE and there is
-                         * an imbalance.
-                         */
-                        if (cpu_isset(cpu, sd->span)) {
-                                schedstat_inc(sd, ttwu_move_balance);
+                }
+
+                /*
+                 * Start passive balancing when half the imbalance_pct
+                 * limit is reached.
+                 */
+                if (this_sd->flags & SD_WAKE_BALANCE) {
+                        if (imbalance*this_load <= 100*load) {
+                                schedstat_inc(this_sd, ttwu_move_balance);
                                 goto out_set_cpu;
                         }
                 }
@@ -1120,17 +1287,19 @@ int fastcall wake_up_state(task_t *p, unsigned int state)
         return try_to_wake_up(p, state, 0);
 }
 
-#ifdef CONFIG_SMP
-static int find_idlest_cpu(struct task_struct *p, int this_cpu,
-                           struct sched_domain *sd);
-#endif
-
 /*
  * Perform scheduler related setup for a newly forked process p.
  * p is forked by current.
  */
-void fastcall sched_fork(task_t *p)
+void fastcall sched_fork(task_t *p, int clone_flags)
 {
+        int cpu = get_cpu();
+
+#ifdef CONFIG_SMP
+        cpu = sched_balance_self(cpu, SD_BALANCE_FORK);
+#endif
+        set_task_cpu(p, cpu);
+
         /*
          * We mark the process as running here, but have not actually
          * inserted it onto the runqueue yet. This guarantees that
@@ -1140,17 +1309,14 @@ void fastcall sched_fork(task_t *p)
         p->state = TASK_RUNNING;
         INIT_LIST_HEAD(&p->run_list);
         p->array = NULL;
-        spin_lock_init(&p->switch_lock);
 #ifdef CONFIG_SCHEDSTATS
         memset(&p->sched_info, 0, sizeof(p->sched_info));
 #endif
+#if defined(CONFIG_SMP) && defined(__ARCH_WANT_UNLOCKED_CTXSW)
+        p->oncpu = 0;
+#endif
 #ifdef CONFIG_PREEMPT
-        /*
-         * During context-switch we hold precisely one spinlock, which
-         * schedule_tail drops. (in the common case it's this_rq()->lock,
-         * but it also can be p->switch_lock.) So we compensate with a count
-         * of 1. Also, we want to start with kernel preemption disabled.
-         */
+        /* Want to start with kernel preemption disabled. */
         p->thread_info->preempt_count = 1;
 #endif
         /*
@@ -1174,12 +1340,10 @@ void fastcall sched_fork(task_t *p)
                  * runqueue lock is not a problem.
                  */
                 current->time_slice = 1;
-                preempt_disable();
                 scheduler_tick();
-                local_irq_enable();
-                preempt_enable();
-        } else
-                local_irq_enable();
+        }
+        local_irq_enable();
+        put_cpu();
 }
 
 /*
@@ -1196,10 +1360,9 @@ void fastcall wake_up_new_task(task_t * p, unsigned long clone_flags)
         runqueue_t *rq, *this_rq;
 
         rq = task_rq_lock(p, &flags);
-        cpu = task_cpu(p);
-        this_cpu = smp_processor_id();
-
         BUG_ON(p->state != TASK_RUNNING);
+        this_cpu = smp_processor_id();
+        cpu = task_cpu(p);
 
         /*
          * We decrease the sleep average of forking parents
@@ -1296,22 +1459,40 @@ void fastcall sched_exit(task_t * p)
 }
 
 /**
+ * prepare_task_switch - prepare to switch tasks
+ * @rq: the runqueue preparing to switch
+ * @next: the task we are going to switch to.
+ *
+ * This is called with the rq lock held and interrupts off. It must
+ * be paired with a subsequent finish_task_switch after the context
+ * switch.
+ *
+ * prepare_task_switch sets up locking and calls architecture specific
+ * hooks.
+ */
+static inline void prepare_task_switch(runqueue_t *rq, task_t *next)
+{
+        prepare_lock_switch(rq, next);
+        prepare_arch_switch(next);
+}
+
+/**
  * finish_task_switch - clean up after a task-switch
  * @prev: the thread we just switched away from.
  *
- * We enter this with the runqueue still locked, and finish_arch_switch()
- * will unlock it along with doing any other architecture-specific cleanup
- * actions.
+ * finish_task_switch must be called after the context switch, paired
+ * with a prepare_task_switch call before the context switch.
+ * finish_task_switch will reconcile locking set up by prepare_task_switch,
+ * and do any other architecture-specific cleanup actions.
  *
  * Note that we may have delayed dropping an mm in context_switch(). If
  * so, we finish that here outside of the runqueue lock.  (Doing it
  * with the lock held can cause deadlocks; see schedule() for
  * details.)
  */
-static inline void finish_task_switch(task_t *prev)
+static inline void finish_task_switch(runqueue_t *rq, task_t *prev)
         __releases(rq->lock)
 {
-        runqueue_t *rq = this_rq();
         struct mm_struct *mm = rq->prev_mm;
         unsigned long prev_task_flags;
 
@@ -1329,7 +1510,8 @@ static inline void finish_task_switch(task_t *prev)
          *              Manfred Spraul <manfred@colorfullife.com>
          */
         prev_task_flags = prev->flags;
-        finish_arch_switch(rq, prev);
+        finish_arch_switch(prev);
+        finish_lock_switch(rq, prev);
         if (mm)
                 mmdrop(mm);
         if (unlikely(prev_task_flags & PF_DEAD))
@@ -1343,8 +1525,12 @@ static inline void finish_task_switch(task_t *prev)
 asmlinkage void schedule_tail(task_t *prev)
         __releases(rq->lock)
 {
-        finish_task_switch(prev);
-
+        runqueue_t *rq = this_rq();
+        finish_task_switch(rq, prev);
+#ifdef __ARCH_WANT_UNLOCKED_CTXSW
+        /* In this case, finish_task_switch does not reenable preemption */
+        preempt_enable();
+#endif
         if (current->set_child_tid)
                 put_user(current->pid, current->set_child_tid);
 }
@@ -1494,51 +1680,6 @@ static void double_lock_balance(runqueue_t *this_rq, runqueue_t *busiest)
 }
 
 /*
- * find_idlest_cpu - find the least busy runqueue.
- */
-static int find_idlest_cpu(struct task_struct *p, int this_cpu,
-                           struct sched_domain *sd)
-{
-        unsigned long load, min_load, this_load;
-        int i, min_cpu;
-        cpumask_t mask;
-
-        min_cpu = UINT_MAX;
-        min_load = ULONG_MAX;
-
-        cpus_and(mask, sd->span, p->cpus_allowed);
-
-        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;
-                }
-        }
-
-        /* 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;
-}
-
-/*
  * 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
@@ -1571,37 +1712,16 @@ out:
 }
 
 /*
- * sched_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.
+ * sched_exec - execve() is a valuable balancing opportunity, because at
+ * this point the task has the smallest effective memory and cache footprint.
  */
 void sched_exec(void)
 {
-        struct sched_domain *tmp, *sd = NULL;
         int new_cpu, this_cpu = get_cpu();
-
-        /* 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) {
-                schedstat_inc(sd, sbe_attempts);
-                new_cpu = find_idlest_cpu(current, this_cpu, sd);
-                if (new_cpu != this_cpu) {
-                        schedstat_inc(sd, sbe_pushed);
-                        put_cpu();
-                        sched_migrate_task(current, new_cpu);
-                        return;
-                }
-        }
-out:
+        new_cpu = sched_balance_self(this_cpu, SD_BALANCE_EXEC);
         put_cpu();
+        if (new_cpu != this_cpu)
+                sched_migrate_task(current, new_cpu);
 }
 
 /*
@@ -1632,7 +1752,7 @@ void pull_task(runqueue_t *src_rq, prio_array_t *src_array, task_t *p,
  */
 static inline
 int can_migrate_task(task_t *p, runqueue_t *rq, int this_cpu,
-                     struct sched_domain *sd, enum idle_type idle)
+             struct sched_domain *sd, enum idle_type idle, int *all_pinned)
 {
         /*
          * We do not migrate tasks that are:
@@ -1640,23 +1760,24 @@ int can_migrate_task(task_t *p, runqueue_t *rq, int this_cpu,
          * 2) cannot be migrated to this CPU due to cpus_allowed, or
          * 3) are cache-hot on their current CPU.
          */
-        if (task_running(rq, p))
-                return 0;
         if (!cpu_isset(this_cpu, p->cpus_allowed))
                 return 0;
+        *all_pinned = 0;
+
+        if (task_running(rq, p))
+                return 0;
 
         /*
          * Aggressive migration if:
-         * 1) the [whole] cpu is idle, or
+         * 1) task is cache cold, or
          * 2) too many balance attempts have failed.
          */
 
-        if (cpu_and_siblings_are_idle(this_cpu) || \
-                        sd->nr_balance_failed > sd->cache_nice_tries)
+        if (sd->nr_balance_failed > sd->cache_nice_tries)
                 return 1;
 
         if (task_hot(p, rq->timestamp_last_tick, sd))
-                        return 0;
+                return 0;
         return 1;
 }
 
@@ -1669,16 +1790,18 @@ int can_migrate_task(task_t *p, runqueue_t *rq, int this_cpu,
  */
 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)
+                      enum idle_type idle, int *all_pinned)
 {
         prio_array_t *array, *dst_array;
         struct list_head *head, *curr;
-        int idx, pulled = 0;
+        int idx, pulled = 0, pinned = 0;
         task_t *tmp;
 
-        if (max_nr_move <= 0 || busiest->nr_running <= 1)
+        if (max_nr_move == 0)
                 goto out;
 
+        pinned = 1;
+
         /*
          * We first consider expired tasks. Those will likely not be
          * executed in the near future, and they are most likely to
@@ -1717,7 +1840,7 @@ skip_queue:
 
         curr = curr->prev;
 
-        if (!can_migrate_task(tmp, busiest, this_cpu, sd, idle)) {
+        if (!can_migrate_task(tmp, busiest, this_cpu, sd, idle, &pinned)) {
                 if (curr != head)
                         goto skip_queue;
                 idx++;
@@ -1746,6 +1869,9 @@ out:
          * inside pull_task().
          */
         schedstat_add(sd, lb_gained[idle], pulled);
+
+        if (all_pinned)
+                *all_pinned = pinned;
         return pulled;
 }
 
@@ -1760,8 +1886,15 @@ find_busiest_group(struct sched_domain *sd, int this_cpu,
 {
         struct sched_group *busiest = NULL, *this = NULL, *group = sd->groups;
         unsigned long max_load, avg_load, total_load, this_load, total_pwr;
+        int load_idx;
 
         max_load = this_load = total_load = total_pwr = 0;
+        if (idle == NOT_IDLE)
+                load_idx = sd->busy_idx;
+        else if (idle == NEWLY_IDLE)
+                load_idx = sd->newidle_idx;
+        else
+                load_idx = sd->idle_idx;
 
         do {
                 unsigned long load;
@@ -1776,9 +1909,9 @@ find_busiest_group(struct sched_domain *sd, int this_cpu,
                 for_each_cpu_mask(i, group->cpumask) {
                         /* Bias balancing toward cpus of our domain */
                         if (local_group)
-                                load = target_load(i);
+                                load = target_load(i, load_idx);
                         else
-                                load = source_load(i);
+                                load = source_load(i, load_idx);
 
                         avg_load += load;
                 }
@@ -1792,12 +1925,10 @@ find_busiest_group(struct sched_domain *sd, int this_cpu,
                 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);
 
@@ -1870,15 +2001,9 @@ nextgroup:
 
         /* Get rid of the scaling factor, rounding down as we divide */
         *imbalance = *imbalance / SCHED_LOAD_SCALE;
-
         return busiest;
 
 out_balanced:
-        if (busiest && (idle == NEWLY_IDLE ||
-                        (idle == SCHED_IDLE && max_load > SCHED_LOAD_SCALE)) ) {
-                *imbalance = 1;
-                return busiest;
-        }
 
         *imbalance = 0;
         return NULL;
@@ -1894,7 +2019,7 @@ static runqueue_t *find_busiest_queue(struct sched_group *group)
         int i;
 
         for_each_cpu_mask(i, group->cpumask) {
-                load = source_load(i);
+                load = source_load(i, 0);
 
                 if (load > max_load) {
                         max_load = load;
@@ -1906,6 +2031,12 @@ static runqueue_t *find_busiest_queue(struct sched_group *group)
 }
 
 /*
+ * Max backoff if we encounter pinned tasks. Pretty arbitrary value, but
+ * so long as it is large enough.
+ */
+#define MAX_PINNED_INTERVAL     512
+
+/*
  * Check this_cpu to ensure it is balanced within domain. Attempt to move
  * tasks if there is an imbalance.
  *
@@ -1917,7 +2048,8 @@ static int load_balance(int this_cpu, runqueue_t *this_rq,
         struct sched_group *group;
         runqueue_t *busiest;
         unsigned long imbalance;
-        int nr_moved;
+        int nr_moved, all_pinned = 0;
+        int active_balance = 0;
 
         spin_lock(&this_rq->lock);
         schedstat_inc(sd, lb_cnt[idle]);
@@ -1934,15 +2066,7 @@ static int load_balance(int this_cpu, runqueue_t *this_rq,
                 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;
-        }
+        BUG_ON(busiest == this_rq);
 
         schedstat_add(sd, lb_imbalance[idle], imbalance);
 
@@ -1956,9 +2080,15 @@ static int load_balance(int this_cpu, runqueue_t *this_rq,
                  */
                 double_lock_balance(this_rq, busiest);
                 nr_moved = move_tasks(this_rq, this_cpu, busiest,
-                                                imbalance, sd, idle);
+                                                imbalance, sd, idle,
+                                                &all_pinned);
                 spin_unlock(&busiest->lock);
+
+                /* All tasks on this runqueue were pinned by CPU affinity */
+                if (unlikely(all_pinned))
+                        goto out_balanced;
         }
+
         spin_unlock(&this_rq->lock);
 
         if (!nr_moved) {
@@ -1966,36 +2096,38 @@ static int load_balance(int this_cpu, runqueue_t *this_rq,
                 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;
+                                active_balance = 1;
                         }
                         spin_unlock(&busiest->lock);
-                        if (wake)
+                        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;
+                        sd->nr_balance_failed = sd->cache_nice_tries+1;
                 }
-
-                /*
-                 * We were unbalanced, but unsuccessful in move_tasks(),
-                 * so bump the balance_interval to lessen the lock contention.
-                 */
-                if (sd->balance_interval < sd->max_interval)
-                        sd->balance_interval++;
-        } else {
+        } 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;
         }
 
         return nr_moved;
@@ -2005,8 +2137,10 @@ out_balanced:
 
         schedstat_inc(sd, lb_balanced[idle]);
 
+        sd->nr_balance_failed = 0;
         /* tune up the balancing interval */
-        if (sd->balance_interval < sd->max_interval)
+        if ((all_pinned && sd->balance_interval < MAX_PINNED_INTERVAL) ||
+                        (sd->balance_interval < sd->max_interval))
                 sd->balance_interval *= 2;
 
         return 0;
@@ -2030,31 +2164,36 @@ static int load_balance_newidle(int this_cpu, runqueue_t *this_rq,
         schedstat_inc(sd, lb_cnt[NEWLY_IDLE]);
         group = find_busiest_group(sd, this_cpu, &imbalance, NEWLY_IDLE);
         if (!group) {
-                schedstat_inc(sd, lb_balanced[NEWLY_IDLE]);
                 schedstat_inc(sd, lb_nobusyg[NEWLY_IDLE]);
-                goto out;
+                goto out_balanced;
         }
 
         busiest = find_busiest_queue(group);
-        if (!busiest || busiest == this_rq) {
-                schedstat_inc(sd, lb_balanced[NEWLY_IDLE]);
+        if (!busiest) {
                 schedstat_inc(sd, lb_nobusyq[NEWLY_IDLE]);
-                goto out;
+                goto out_balanced;
         }
 
+        BUG_ON(busiest == this_rq);
+
         /* Attempt to move tasks */
         double_lock_balance(this_rq, busiest);
 
         schedstat_add(sd, lb_imbalance[NEWLY_IDLE], imbalance);
         nr_moved = move_tasks(this_rq, this_cpu, busiest,
-                                        imbalance, sd, NEWLY_IDLE);
+                                        imbalance, sd, NEWLY_IDLE, NULL);
         if (!nr_moved)
                 schedstat_inc(sd, lb_failed[NEWLY_IDLE]);
+        else
+                sd->nr_balance_failed = 0;
 
         spin_unlock(&busiest->lock);
-
-out:
         return nr_moved;
+
+out_balanced:
+        schedstat_inc(sd, lb_balanced[NEWLY_IDLE]);
+        sd->nr_balance_failed = 0;
+        return 0;
 }
 
 /*
@@ -2086,56 +2225,42 @@ static inline void idle_balance(int this_cpu, runqueue_t *this_rq)
 static void active_load_balance(runqueue_t *busiest_rq, int busiest_cpu)
 {
         struct sched_domain *sd;
-        struct sched_group *cpu_group;
         runqueue_t *target_rq;
-        cpumask_t visited_cpus;
-        int cpu;
+        int target_cpu = busiest_rq->push_cpu;
+
+        if (busiest_rq->nr_running <= 1)
+                /* no task to move */
+                return;
+
+        target_rq = cpu_rq(target_cpu);
 
         /*
-         * Search for suitable CPUs to push tasks to in successively higher
-         * domains with SD_LOAD_BALANCE set.
+         * This condition is "impossible", if it occurs
+         * we need to fix it.  Originally reported by
+         * Bjorn Helgaas on a 128-cpu setup.
          */
-        visited_cpus = CPU_MASK_NONE;
-        for_each_domain(busiest_cpu, sd) {
-                if (!(sd->flags & SD_LOAD_BALANCE))
-                        /* no more domains to search */
-                        break;
+        BUG_ON(busiest_rq == target_rq);
 
-                schedstat_inc(sd, alb_cnt);
+        /* move a task from busiest_rq to target_rq */
+        double_lock_balance(busiest_rq, target_rq);
 
-                cpu_group = sd->groups;
-                do {
-                        for_each_cpu_mask(cpu, cpu_group->cpumask) {
-                                if (busiest_rq->nr_running <= 1)
-                                        /* no more tasks left to move */
-                                        return;
-                                if (cpu_isset(cpu, visited_cpus))
-                                        continue;
-                                cpu_set(cpu, visited_cpus);
-                                if (!cpu_and_siblings_are_idle(cpu) || cpu == busiest_cpu)
-                                        continue;
-
-                                target_rq = cpu_rq(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);
-                                if (move_tasks(target_rq, cpu, busiest_rq,
-                                                1, sd, SCHED_IDLE)) {
-                                        schedstat_inc(sd, alb_pushed);
-                                } else {
-                                        schedstat_inc(sd, alb_failed);
-                                }
-                                spin_unlock(&target_rq->lock);
-                        }
-                        cpu_group = cpu_group->next;
-                } while (cpu_group != sd->groups);
-        }
+        /* Search for an sd spanning us and the target CPU. */
+        for_each_domain(target_cpu, sd)
+                if ((sd->flags & SD_LOAD_BALANCE) &&
+                        cpu_isset(busiest_cpu, sd->span))
+                                break;
+
+        if (unlikely(sd == NULL))
+                goto out;
+
+        schedstat_inc(sd, alb_cnt);
+
+        if (move_tasks(target_rq, target_cpu, busiest_rq, 1, sd, SCHED_IDLE, NULL))
+                schedstat_inc(sd, alb_pushed);
+        else
+                schedstat_inc(sd, alb_failed);
+out:
+        spin_unlock(&target_rq->lock);
 }
 
 /*
@@ -2156,18 +2281,23 @@ static void rebalance_tick(int this_cpu, runqueue_t *this_rq,
         unsigned long old_load, this_load;
         unsigned long j = jiffies + CPU_OFFSET(this_cpu);
         struct sched_domain *sd;
+        int i;
 
-        /* Update our load */
-        old_load = this_rq->cpu_load;
         this_load = this_rq->nr_running * SCHED_LOAD_SCALE;
-        /*
-         * 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 (this_load > old_load)
-                old_load++;
-        this_rq->cpu_load = (old_load + this_load) / 2;
+        /* Update our load */
+        for (i = 0; i < 3; i++) {
+                unsigned long new_load = this_load;
+                int scale = 1 << i;
+                old_load = this_rq->cpu_load[i];
+                /*
+                 * 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 (new_load > old_load)
+                        new_load += scale-1;
+                this_rq->cpu_load[i] = (old_load*(scale-1) + new_load) / scale;
+        }
 
         for_each_domain(this_cpu, sd) {
                 unsigned long interval;
@@ -2447,11 +2577,15 @@ out:
 #ifdef CONFIG_SCHED_SMT
 static inline void wake_sleeping_dependent(int this_cpu, runqueue_t *this_rq)
 {
-        struct sched_domain *sd = this_rq->sd;
+        struct sched_domain *tmp, *sd = NULL;
         cpumask_t sibling_map;
         int i;
 
-        if (!(sd->flags & SD_SHARE_CPUPOWER))
+        for_each_domain(this_cpu, tmp)
+                if (tmp->flags & SD_SHARE_CPUPOWER)
+                        sd = tmp;
+
+        if (!sd)
                 return;
 
         /*
@@ -2492,13 +2626,17 @@ static inline void wake_sleeping_dependent(int this_cpu, runqueue_t *this_rq)
 
 static inline int dependent_sleeper(int this_cpu, runqueue_t *this_rq)
 {
-        struct sched_domain *sd = this_rq->sd;
+        struct sched_domain *tmp, *sd = NULL;
         cpumask_t sibling_map;
         prio_array_t *array;
         int ret = 0, i;
         task_t *p;
 
-        if (!(sd->flags & SD_SHARE_CPUPOWER))
+        for_each_domain(this_cpu, tmp)
+                if (tmp->flags & SD_SHARE_CPUPOWER)
+                        sd = tmp;
+
+        if (!sd)
                 return 0;
 
         /*
@@ -2576,7 +2714,7 @@ void fastcall add_preempt_count(int val)
         /*
          * Underflow?
          */
-        BUG_ON(((int)preempt_count() < 0));
+        BUG_ON((preempt_count() < 0));
         preempt_count() += val;
         /*
          * Spinlock count overflowing soon?
@@ -2613,7 +2751,7 @@ asmlinkage void __sched schedule(void)
         struct list_head *queue;
         unsigned long long now;
         unsigned long run_time;
-        int cpu, idx;
+        int cpu, idx, new_prio;
 
         /*
          * Test if we are atomic.  Since do_exit() needs to call into
@@ -2735,9 +2873,14 @@ go_idle:
                         delta = delta * (ON_RUNQUEUE_WEIGHT * 128 / 100) / 128;
 
                 array = next->array;
-                dequeue_task(next, array);
-                recalc_task_prio(next, next->timestamp + delta);
-                enqueue_task(next, array);
+                new_prio = recalc_task_prio(next, next->timestamp + delta);
+
+                if (unlikely(next->prio != new_prio)) {
+                        dequeue_task(next, array);
+                        next->prio = new_prio;
+                        enqueue_task(next, array);
+                } else
+                        requeue_task(next, array);
         }
         next->activated = 0;
 switch_tasks:
@@ -2761,11 +2904,15 @@ switch_tasks:
                 rq->curr = next;
                 ++*switch_count;
 
-                prepare_arch_switch(rq, next);
+                prepare_task_switch(rq, next);
                 prev = context_switch(rq, prev, next);
                 barrier();
-
-                finish_task_switch(prev);
+                /*
+                 * this_rq must be evaluated again because prev may have moved
+                 * CPUs since it called schedule(), thus the 'rq' on its stack
+                 * frame will be invalid.
+                 */
+                finish_task_switch(this_rq(), prev);
         } else
                 spin_unlock_irq(&rq->lock);
 
@@ -2869,7 +3016,7 @@ need_resched:
 
 int default_wake_function(wait_queue_t *curr, unsigned mode, int sync, void *key)
 {
-        task_t *p = curr->task;
+        task_t *p = curr->private;
         return try_to_wake_up(p, mode, sync);
 }
 
@@ -3301,15 +3448,7 @@ int task_nice(const task_t *p)
 {
         return TASK_NICE(p);
 }
-
-/*
- * The only users of task_nice are binfmt_elf and binfmt_elf32.
- * binfmt_elf is no longer modular, but binfmt_elf32 still is.
- * Therefore, task_nice is needed if there is a compat_mode.
- */
-#ifdef CONFIG_COMPAT
 EXPORT_SYMBOL_GPL(task_nice);
-#endif
 
 /**
  * idle_cpu - is a given cpu idle currently?
@@ -3384,13 +3523,24 @@ recheck:
         if ((policy == SCHED_NORMAL) != (param->sched_priority == 0))
                 return -EINVAL;
 
-        if ((policy == SCHED_FIFO || policy == SCHED_RR) &&
-            param->sched_priority > p->signal->rlim[RLIMIT_RTPRIO].rlim_cur &&
-            !capable(CAP_SYS_NICE))
-                return -EPERM;
-        if ((current->euid != p->euid) && (current->euid != p->uid) &&
-            !capable(CAP_SYS_NICE))
-                return -EPERM;
+        /*
+         * Allow unprivileged RT tasks to decrease priority:
+         */
+        if (!capable(CAP_SYS_NICE)) {
+                /* can't change policy */
+                if (policy != p->policy)
+                        return -EPERM;
+                /* can't increase priority */
+                if (policy != SCHED_NORMAL &&
+                    param->sched_priority > p->rt_priority &&
+                    param->sched_priority >
+                                p->signal->rlim[RLIMIT_RTPRIO].rlim_cur)
+                        return -EPERM;
+                /* can't change other user's priorities */
+                if ((current->euid != p->euid) &&
+                    (current->euid != p->uid))
+                        return -EPERM;
+        }
 
         retval = security_task_setscheduler(p, policy, param);
         if (retval)
@@ -3814,7 +3964,7 @@ EXPORT_SYMBOL(yield);
  */
 void __sched io_schedule(void)
 {
-        struct runqueue *rq = &per_cpu(runqueues, _smp_processor_id());
+        struct runqueue *rq = &per_cpu(runqueues, raw_smp_processor_id());
 
         atomic_inc(&rq->nr_iowait);
         schedule();
@@ -3825,7 +3975,7 @@ EXPORT_SYMBOL(io_schedule);
 
 long __sched io_schedule_timeout(long timeout)
 {
-        struct runqueue *rq = &per_cpu(runqueues, _smp_processor_id());
+        struct runqueue *rq = &per_cpu(runqueues, raw_smp_processor_id());
         long ret;
 
         atomic_inc(&rq->nr_iowait);
@@ -4016,6 +4166,14 @@ void show_state(void)
         read_unlock(&tasklist_lock);
 }
 
+/**
+ * init_idle - set up an idle thread for a given CPU
+ * @idle: task in question
+ * @cpu: cpu the idle task belongs to
+ *
+ * NOTE: this function does not set the idle thread's NEED_RESCHED
+ * flag, to make booting more robust.
+ */
 void __devinit init_idle(task_t *idle, int cpu)
 {
         runqueue_t *rq = cpu_rq(cpu);
@@ -4030,7 +4188,9 @@ void __devinit init_idle(task_t *idle, int cpu)
 
         spin_lock_irqsave(&rq->lock, flags);
         rq->curr = rq->idle = idle;
-        set_tsk_need_resched(idle);
+#if defined(CONFIG_SMP) && defined(__ARCH_WANT_UNLOCKED_CTXSW)
+        idle->oncpu = 1;
+#endif
         spin_unlock_irqrestore(&rq->lock, flags);
 
         /* Set the preempt count _outside_ the spinlocks! */
@@ -4174,8 +4334,7 @@ static int migration_thread(void * data)
                 struct list_head *head;
                 migration_req_t *req;
 
-                if (current->flags & PF_FREEZE)
-                        refrigerator(PF_FREEZE);
+                try_to_freeze();
 
                 spin_lock_irq(&rq->lock);
 
@@ -4200,17 +4359,9 @@ static int migration_thread(void * data)
                 req = list_entry(head->next, migration_req_t, list);
                 list_del_init(head->next);
 
-                if (req->type == REQ_MOVE_TASK) {
-                        spin_unlock(&rq->lock);
-                        __migrate_task(req->task, cpu, 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);
-                }
+                spin_unlock(&rq->lock);
+                __migrate_task(req->task, cpu, req->dest_cpu);
+                local_irq_enable();
 
                 complete(&req->done);
         }
@@ -4441,7 +4592,6 @@ static int migration_call(struct notifier_block *nfb, unsigned long action,
                         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);
                 }
@@ -4472,12 +4622,17 @@ int __init migration_init(void)
 #endif
 
 #ifdef CONFIG_SMP
-#define SCHED_DOMAIN_DEBUG
+#undef SCHED_DOMAIN_DEBUG
 #ifdef SCHED_DOMAIN_DEBUG
 static void sched_domain_debug(struct sched_domain *sd, int cpu)
 {
         int level = 0;
 
+        if (!sd) {
+                printk(KERN_DEBUG "CPU%d attaching NULL sched-domain.\n", cpu);
+                return;
+        }
+
         printk(KERN_DEBUG "CPU%d attaching sched-domain:\n", cpu);
 
         do {
@@ -4560,37 +4715,81 @@ static void sched_domain_debug(struct sched_domain *sd, int cpu)
 #define sched_domain_debug(sd, cpu) {}
 #endif
 
+static int sd_degenerate(struct sched_domain *sd)
+{
+        if (cpus_weight(sd->span) == 1)
+                return 1;
+
+        /* Following flags need at least 2 groups */
+        if (sd->flags & (SD_LOAD_BALANCE |
+                         SD_BALANCE_NEWIDLE |
+                         SD_BALANCE_FORK |
+                         SD_BALANCE_EXEC)) {
+                if (sd->groups != sd->groups->next)
+                        return 0;
+        }
+
+        /* Following flags don't use groups */
+        if (sd->flags & (SD_WAKE_IDLE |
+                         SD_WAKE_AFFINE |
+                         SD_WAKE_BALANCE))
+                return 0;
+
+        return 1;
+}
+
+static int sd_parent_degenerate(struct sched_domain *sd,
+                                                struct sched_domain *parent)
+{
+        unsigned long cflags = sd->flags, pflags = parent->flags;
+
+        if (sd_degenerate(parent))
+                return 1;
+
+        if (!cpus_equal(sd->span, parent->span))
+                return 0;
+
+        /* Does parent contain flags not in child? */
+        /* WAKE_BALANCE is a subset of WAKE_AFFINE */
+        if (cflags & SD_WAKE_AFFINE)
+                pflags &= ~SD_WAKE_BALANCE;
+        /* Flags needing groups don't count if only 1 group in parent */
+        if (parent->groups == parent->groups->next) {
+                pflags &= ~(SD_LOAD_BALANCE |
+                                SD_BALANCE_NEWIDLE |
+                                SD_BALANCE_FORK |
+                                SD_BALANCE_EXEC);
+        }
+        if (~cflags & pflags)
+                return 0;
+
+        return 1;
+}
+
 /*
  * Attach the domain 'sd' to 'cpu' as its base domain.  Callers must
  * hold the hotplug lock.
  */
-void __devinit cpu_attach_domain(struct sched_domain *sd, int cpu)
+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;
-
-        sched_domain_debug(sd, cpu);
+        struct sched_domain *tmp;
 
-        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;
+        /* Remove the sched domains which do not contribute to scheduling. */
+        for (tmp = sd; tmp; tmp = tmp->parent) {
+                struct sched_domain *parent = tmp->parent;
+                if (!parent)
+                        break;
+                if (sd_parent_degenerate(tmp, parent))
+                        tmp->parent = parent->parent;
         }
 
-        spin_unlock_irqrestore(&rq->lock, flags);
+        if (sd && sd_degenerate(sd))
+                sd = sd->parent;
 
-        if (!local) {
-                wake_up_process(rq->migration_thread);
-                wait_for_completion(&req.done);
-        }
+        sched_domain_debug(sd, cpu);
+
+        rcu_assign_pointer(rq->sd, sd);
 }
 
 /* cpus with isolated domains */
@@ -4622,7 +4821,7 @@ __setup ("isolcpus=", isolated_cpu_setup);
  * covered by the given span, and will set each group's ->cpumask correctly,
  * and ->cpu_power to 0.
  */
-void __devinit init_sched_build_groups(struct sched_group groups[],
+void init_sched_build_groups(struct sched_group groups[],
                         cpumask_t span, int (*group_fn)(int cpu))
 {
         struct sched_group *first = NULL, *last = NULL;
@@ -4658,13 +4857,14 @@ void __devinit init_sched_build_groups(struct sched_group groups[],
 
 
 #ifdef ARCH_HAS_SCHED_DOMAIN
-extern void __devinit arch_init_sched_domains(void);
-extern void __devinit arch_destroy_sched_domains(void);
+extern void build_sched_domains(const cpumask_t *cpu_map);
+extern void arch_init_sched_domains(const cpumask_t *cpu_map);
+extern void arch_destroy_sched_domains(const cpumask_t *cpu_map);
 #else
 #ifdef CONFIG_SCHED_SMT
 static DEFINE_PER_CPU(struct sched_domain, cpu_domains);
 static struct sched_group sched_group_cpus[NR_CPUS];
-static int __devinit cpu_to_cpu_group(int cpu)
+static int cpu_to_cpu_group(int cpu)
 {
         return cpu;
 }
@@ -4672,7 +4872,7 @@ static int __devinit cpu_to_cpu_group(int cpu)
 
 static DEFINE_PER_CPU(struct sched_domain, phys_domains);
 static struct sched_group sched_group_phys[NR_CPUS];
-static int __devinit cpu_to_phys_group(int cpu)
+static int cpu_to_phys_group(int cpu)
 {
 #ifdef CONFIG_SCHED_SMT
         return first_cpu(cpu_sibling_map[cpu]);
@@ -4685,7 +4885,7 @@ static int __devinit cpu_to_phys_group(int cpu)
 
 static DEFINE_PER_CPU(struct sched_domain, node_domains);
 static struct sched_group sched_group_nodes[MAX_NUMNODES];
-static int __devinit cpu_to_node_group(int cpu)
+static int cpu_to_node_group(int cpu)
 {
         return cpu_to_node(cpu);
 }
@@ -4716,39 +4916,28 @@ static void check_sibling_maps(void)
 #endif
 
 /*
- * Set up scheduler domains and groups.  Callers must hold the hotplug lock.
+ * Build sched domains for a given set of cpus and attach the sched domains
+ * to the individual cpus
  */
-static void __devinit arch_init_sched_domains(void)
+static void build_sched_domains(const cpumask_t *cpu_map)
 {
         int i;
-        cpumask_t cpu_default_map;
-
-#if defined(CONFIG_SCHED_SMT) && defined(CONFIG_NUMA)
-        check_sibling_maps();
-#endif
-        /*
-         * Setup mask for cpus without special case scheduling requirements.
-         * For now this just excludes isolated cpus, but could be used to
-         * exclude other special cases in the future.
-         */
-        cpus_complement(cpu_default_map, cpu_isolated_map);
-        cpus_and(cpu_default_map, cpu_default_map, cpu_online_map);
 
         /*
-         * Set up domains. Isolated domains just stay on the dummy domain.
+         * Set up domains for cpus specified by the cpu_map.
          */
-        for_each_cpu_mask(i, cpu_default_map) {
+        for_each_cpu_mask(i, *cpu_map) {
                 int group;
                 struct sched_domain *sd = NULL, *p;
                 cpumask_t nodemask = node_to_cpumask(cpu_to_node(i));
 
-                cpus_and(nodemask, nodemask, cpu_default_map);
+                cpus_and(nodemask, nodemask, *cpu_map);
 
 #ifdef CONFIG_NUMA
                 sd = &per_cpu(node_domains, i);
                 group = cpu_to_node_group(i);
                 *sd = SD_NODE_INIT;
-                sd->span = cpu_default_map;
+                sd->span = *cpu_map;
                 sd->groups = &sched_group_nodes[group];
 #endif
 
@@ -4766,7 +4955,7 @@ static void __devinit arch_init_sched_domains(void)
                 group = cpu_to_cpu_group(i);
                 *sd = SD_SIBLING_INIT;
                 sd->span = cpu_sibling_map[i];
-                cpus_and(sd->span, sd->span, cpu_default_map);
+                cpus_and(sd->span, sd->span, *cpu_map);
                 sd->parent = p;
                 sd->groups = &sched_group_cpus[group];
 #endif
@@ -4776,7 +4965,7 @@ static void __devinit arch_init_sched_domains(void)
         /* Set up CPU (sibling) groups */
         for_each_online_cpu(i) {
                 cpumask_t this_sibling_map = cpu_sibling_map[i];
-                cpus_and(this_sibling_map, this_sibling_map, cpu_default_map);
+                cpus_and(this_sibling_map, this_sibling_map, *cpu_map);
                 if (i != first_cpu(this_sibling_map))
                         continue;
 
@@ -4789,7 +4978,7 @@ static void __devinit arch_init_sched_domains(void)
         for (i = 0; i < MAX_NUMNODES; i++) {
                 cpumask_t nodemask = node_to_cpumask(i);
 
-                cpus_and(nodemask, nodemask, cpu_default_map);
+                cpus_and(nodemask, nodemask, *cpu_map);
                 if (cpus_empty(nodemask))
                         continue;
 
@@ -4799,12 +4988,12 @@ static void __devinit arch_init_sched_domains(void)
 
 #ifdef CONFIG_NUMA
         /* Set up node groups */
-        init_sched_build_groups(sched_group_nodes, cpu_default_map,
+        init_sched_build_groups(sched_group_nodes, *cpu_map,
                                         &cpu_to_node_group);
 #endif
 
         /* Calculate CPU power for physical packages and nodes */
-        for_each_cpu_mask(i, cpu_default_map) {
+        for_each_cpu_mask(i, *cpu_map) {
                 int power;
                 struct sched_domain *sd;
 #ifdef CONFIG_SCHED_SMT
@@ -4828,7 +5017,7 @@ static void __devinit arch_init_sched_domains(void)
         }
 
         /* Attach the domains */
-        for_each_online_cpu(i) {
+        for_each_cpu_mask(i, *cpu_map) {
                 struct sched_domain *sd;
 #ifdef CONFIG_SCHED_SMT
                 sd = &per_cpu(cpu_domains, i);
@@ -4838,41 +5027,85 @@ static void __devinit arch_init_sched_domains(void)
                 cpu_attach_domain(sd, i);
         }
 }
+/*
+ * Set up scheduler domains and groups.  Callers must hold the hotplug lock.
+ */
+static void arch_init_sched_domains(cpumask_t *cpu_map)
+{
+        cpumask_t cpu_default_map;
+
+#if defined(CONFIG_SCHED_SMT) && defined(CONFIG_NUMA)
+        check_sibling_maps();
+#endif
+        /*
+         * Setup mask for cpus without special case scheduling requirements.
+         * For now this just excludes isolated cpus, but could be used to
+         * exclude other special cases in the future.
+         */
+        cpus_andnot(cpu_default_map, *cpu_map, cpu_isolated_map);
+
+        build_sched_domains(&cpu_default_map);
+}
 
-#ifdef CONFIG_HOTPLUG_CPU
-static void __devinit arch_destroy_sched_domains(void)
+static void arch_destroy_sched_domains(const cpumask_t *cpu_map)
 {
         /* Do nothing: everything is statically allocated. */
 }
-#endif
 
 #endif /* ARCH_HAS_SCHED_DOMAIN */
 
 /*
- * Initial dummy domain for early boot and for hotplug cpu. Being static,
- * it is initialized to zero, so all balancing flags are cleared which is
- * what we want.
+ * Detach sched domains from a group of cpus specified in cpu_map
+ * These cpus will now be attached to the NULL domain
  */
-static struct sched_domain sched_domain_dummy;
+static inline void detach_destroy_domains(const cpumask_t *cpu_map)
+{
+        int i;
+
+        for_each_cpu_mask(i, *cpu_map)
+                cpu_attach_domain(NULL, i);
+        synchronize_sched();
+        arch_destroy_sched_domains(cpu_map);
+}
+
+/*
+ * Partition sched domains as specified by the cpumasks below.
+ * This attaches all cpus from the cpumasks to the NULL domain,
+ * waits for a RCU quiescent period, recalculates sched
+ * domain information and then attaches them back to the
+ * correct sched domains
+ * Call with hotplug lock held
+ */
+void partition_sched_domains(cpumask_t *partition1, cpumask_t *partition2)
+{
+        cpumask_t change_map;
+
+        cpus_and(*partition1, *partition1, cpu_online_map);
+        cpus_and(*partition2, *partition2, cpu_online_map);
+        cpus_or(change_map, *partition1, *partition2);
+
+        /* Detach sched domains from all of the affected cpus */
+        detach_destroy_domains(&change_map);
+        if (!cpus_empty(*partition1))
+                build_sched_domains(partition1);
+        if (!cpus_empty(*partition2))
+                build_sched_domains(partition2);
+}
 
 #ifdef CONFIG_HOTPLUG_CPU
 /*
  * Force a reinitialization of the sched domains hierarchy.  The domains
  * and groups cannot be updated in place without racing with the balancing
- * code, so we temporarily attach all running cpus to a "dummy" domain
+ * code, so we temporarily attach all running cpus to the NULL domain
  * which will prevent rebalancing while the sched domains are recalculated.
  */
 static int update_sched_domains(struct notifier_block *nfb,
                                 unsigned long action, void *hcpu)
 {
-        int i;
-
         switch (action) {
         case CPU_UP_PREPARE:
         case CPU_DOWN_PREPARE:
-                for_each_online_cpu(i)
-                        cpu_attach_domain(&sched_domain_dummy, i);
-                arch_destroy_sched_domains();
+                detach_destroy_domains(&cpu_online_map);
                 return NOTIFY_OK;
 
         case CPU_UP_CANCELED:
@@ -4888,7 +5121,7 @@ static int update_sched_domains(struct notifier_block *nfb,
         }
 
         /* The hotplug lock is already held by cpu_up/cpu_down */
-        arch_init_sched_domains();
+        arch_init_sched_domains(&cpu_online_map);
 
         return NOTIFY_OK;
 }
@@ -4897,7 +5130,7 @@ static int update_sched_domains(struct notifier_block *nfb,
 void __init sched_init_smp(void)
 {
         lock_cpu_hotplug();
-        arch_init_sched_domains();
+        arch_init_sched_domains(&cpu_online_map);
         unlock_cpu_hotplug();
         /* XXX: Theoretical race here - CPU may be hotplugged now */
         hotcpu_notifier(update_sched_domains, 0);
@@ -4927,13 +5160,15 @@ void __init sched_init(void)
 
                 rq = cpu_rq(i);
                 spin_lock_init(&rq->lock);
+                rq->nr_running = 0;
                 rq->active = rq->arrays;
                 rq->expired = rq->arrays + 1;
                 rq->best_expired_prio = MAX_PRIO;
 
 #ifdef CONFIG_SMP
-                rq->sd = &sched_domain_dummy;
-                rq->cpu_load = 0;
+                rq->sd = NULL;
+                for (j = 1; j < 3; j++)
+                        rq->cpu_load[j] = 0;
                 rq->active_balance = 0;
                 rq->push_cpu = 0;
                 rq->migration_thread = NULL;