1 files changed, 328 insertions, 483 deletions

diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c
index 67c67a87146e..a17b785d7000 100644
--- a/kernel/sched_fair.c
+++ b/kernel/sched_fair.c
@@ -25,22 +25,26 @@
  * (default: 20ms, units: nanoseconds)
  *
  * NOTE: this latency value is not the same as the concept of
- * 'timeslice length' - timeslices in CFS are of variable length.
- * (to see the precise effective timeslice length of your workload,
- *  run vmstat and monitor the context-switches field)
+ * 'timeslice length' - timeslices in CFS are of variable length
+ * and have no persistent notion like in traditional, time-slice
+ * based scheduling concepts.
  *
- * On SMP systems the value of this is multiplied by the log2 of the
- * number of CPUs. (i.e. factor 2x on 2-way systems, 3x on 4-way
- * systems, 4x on 8-way systems, 5x on 16-way systems, etc.)
- * Targeted preemption latency for CPU-bound tasks:
+ * (to see the precise effective timeslice length of your workload,
+ *  run vmstat and monitor the context-switches (cs) field)
  */
-unsigned int sysctl_sched_latency __read_mostly = 20000000ULL;
+const_debug unsigned int sysctl_sched_latency = 20000000ULL;
+
+/*
+ * After fork, child runs first. (default) If set to 0 then
+ * parent will (try to) run first.
+ */
+const_debug unsigned int sysctl_sched_child_runs_first = 1;
 
 /*
  * Minimal preemption granularity for CPU-bound tasks:
  * (default: 2 msec, units: nanoseconds)
  */
-unsigned int sysctl_sched_min_granularity __read_mostly = 2000000ULL;
+const_debug unsigned int sysctl_sched_nr_latency = 20;
 
 /*
  * sys_sched_yield() compat mode
@@ -52,52 +56,25 @@ unsigned int __read_mostly sysctl_sched_compat_yield;
 
 /*
  * SCHED_BATCH wake-up granularity.
- * (default: 25 msec, units: nanoseconds)
+ * (default: 10 msec, units: nanoseconds)
  *
  * This option delays the preemption effects of decoupled workloads
  * and reduces their over-scheduling. Synchronous workloads will still
  * have immediate wakeup/sleep latencies.
  */
-unsigned int sysctl_sched_batch_wakeup_granularity __read_mostly = 25000000UL;
+const_debug unsigned int sysctl_sched_batch_wakeup_granularity = 10000000UL;
 
 /*
  * SCHED_OTHER wake-up granularity.
- * (default: 1 msec, units: nanoseconds)
+ * (default: 10 msec, units: nanoseconds)
  *
  * This option delays the preemption effects of decoupled workloads
  * and reduces their over-scheduling. Synchronous workloads will still
  * have immediate wakeup/sleep latencies.
  */
-unsigned int sysctl_sched_wakeup_granularity __read_mostly = 1000000UL;
-
-unsigned int sysctl_sched_stat_granularity __read_mostly;
-
-/*
- * Initialized in sched_init_granularity() [to 5 times the base granularity]:
- */
-unsigned int sysctl_sched_runtime_limit __read_mostly;
-
-/*
- * Debugging: various feature bits
- */
-enum {
-        SCHED_FEAT_FAIR_SLEEPERS        = 1,
-        SCHED_FEAT_SLEEPER_AVG          = 2,
-        SCHED_FEAT_SLEEPER_LOAD_AVG     = 4,
-        SCHED_FEAT_PRECISE_CPU_LOAD     = 8,
-        SCHED_FEAT_START_DEBIT          = 16,
-        SCHED_FEAT_SKIP_INITIAL         = 32,
-};
+const_debug unsigned int sysctl_sched_wakeup_granularity = 10000000UL;
 
-unsigned int sysctl_sched_features __read_mostly =
-                SCHED_FEAT_FAIR_SLEEPERS        *1 |
-                SCHED_FEAT_SLEEPER_AVG          *0 |
-                SCHED_FEAT_SLEEPER_LOAD_AVG     *1 |
-                SCHED_FEAT_PRECISE_CPU_LOAD     *1 |
-                SCHED_FEAT_START_DEBIT          *1 |
-                SCHED_FEAT_SKIP_INITIAL         *0;
-
-extern struct sched_class fair_sched_class;
+const_debug unsigned int sysctl_sched_migration_cost = 500000UL;
 
 /**************************************************************
  * CFS operations on generic schedulable entities:
@@ -111,21 +88,9 @@ static inline struct rq *rq_of(struct cfs_rq *cfs_rq)
         return cfs_rq->rq;
 }
 
-/* currently running entity (if any) on this cfs_rq */
-static inline struct sched_entity *cfs_rq_curr(struct cfs_rq *cfs_rq)
-{
-        return cfs_rq->curr;
-}
-
 /* An entity is a task if it doesn't "own" a runqueue */
 #define entity_is_task(se)      (!se->my_q)
 
-static inline void
-set_cfs_rq_curr(struct cfs_rq *cfs_rq, struct sched_entity *se)
-{
-        cfs_rq->curr = se;
-}
-
 #else   /* CONFIG_FAIR_GROUP_SCHED */
 
 static inline struct rq *rq_of(struct cfs_rq *cfs_rq)
@@ -133,21 +98,8 @@ static inline struct rq *rq_of(struct cfs_rq *cfs_rq)
         return container_of(cfs_rq, struct rq, cfs);
 }
 
-static inline struct sched_entity *cfs_rq_curr(struct cfs_rq *cfs_rq)
-{
-        struct rq *rq = rq_of(cfs_rq);
-
-        if (unlikely(rq->curr->sched_class != &fair_sched_class))
-                return NULL;
-
-        return &rq->curr->se;
-}
-
 #define entity_is_task(se)      1
 
-static inline void
-set_cfs_rq_curr(struct cfs_rq *cfs_rq, struct sched_entity *se) { }
-
 #endif  /* CONFIG_FAIR_GROUP_SCHED */
 
 static inline struct task_struct *task_of(struct sched_entity *se)
@@ -160,16 +112,38 @@ static inline struct task_struct *task_of(struct sched_entity *se)
  * Scheduling class tree data structure manipulation methods:
  */
 
+static inline u64 max_vruntime(u64 min_vruntime, u64 vruntime)
+{
+        s64 delta = (s64)(vruntime - min_vruntime);
+        if (delta > 0)
+                min_vruntime = vruntime;
+
+        return min_vruntime;
+}
+
+static inline u64 min_vruntime(u64 min_vruntime, u64 vruntime)
+{
+        s64 delta = (s64)(vruntime - min_vruntime);
+        if (delta < 0)
+                min_vruntime = vruntime;
+
+        return min_vruntime;
+}
+
+static inline s64 entity_key(struct cfs_rq *cfs_rq, struct sched_entity *se)
+{
+        return se->vruntime - cfs_rq->min_vruntime;
+}
+
 /*
  * Enqueue an entity into the rb-tree:
  */
-static inline void
-__enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se)
+static void __enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se)
 {
         struct rb_node **link = &cfs_rq->tasks_timeline.rb_node;
         struct rb_node *parent = NULL;
         struct sched_entity *entry;
-        s64 key = se->fair_key;
+        s64 key = entity_key(cfs_rq, se);
         int leftmost = 1;
 
         /*
@@ -182,7 +156,7 @@ __enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se)
                  * We dont care about collisions. Nodes with
                  * the same key stay together.
                  */
-                if (key - entry->fair_key < 0) {
+                if (key < entity_key(cfs_rq, entry)) {
                         link = &parent->rb_left;
                 } else {
                         link = &parent->rb_right;
@@ -199,24 +173,14 @@ __enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se)
 
         rb_link_node(&se->run_node, parent, link);
         rb_insert_color(&se->run_node, &cfs_rq->tasks_timeline);
-        update_load_add(&cfs_rq->load, se->load.weight);
-        cfs_rq->nr_running++;
-        se->on_rq = 1;
-
-        schedstat_add(cfs_rq, wait_runtime, se->wait_runtime);
 }
 
-static inline void
-__dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se)
+static void __dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se)
 {
         if (cfs_rq->rb_leftmost == &se->run_node)
                 cfs_rq->rb_leftmost = rb_next(&se->run_node);
-        rb_erase(&se->run_node, &cfs_rq->tasks_timeline);
-        update_load_sub(&cfs_rq->load, se->load.weight);
-        cfs_rq->nr_running--;
-        se->on_rq = 0;
 
-        schedstat_add(cfs_rq, wait_runtime, -se->wait_runtime);
+        rb_erase(&se->run_node, &cfs_rq->tasks_timeline);
 }
 
 static inline struct rb_node *first_fair(struct cfs_rq *cfs_rq)
@@ -229,118 +193,86 @@ static struct sched_entity *__pick_next_entity(struct cfs_rq *cfs_rq)
         return rb_entry(first_fair(cfs_rq), struct sched_entity, run_node);
 }
 
+static inline struct sched_entity *__pick_last_entity(struct cfs_rq *cfs_rq)
+{
+        struct rb_node **link = &cfs_rq->tasks_timeline.rb_node;
+        struct sched_entity *se = NULL;
+        struct rb_node *parent;
+
+        while (*link) {
+                parent = *link;
+                se = rb_entry(parent, struct sched_entity, run_node);
+                link = &parent->rb_right;
+        }
+
+        return se;
+}
+
 /**************************************************************
  * Scheduling class statistics methods:
  */
 
+
 /*
- * Calculate the preemption granularity needed to schedule every
- * runnable task once per sysctl_sched_latency amount of time.
- * (down to a sensible low limit on granularity)
- *
- * For example, if there are 2 tasks running and latency is 10 msecs,
- * we switch tasks every 5 msecs. If we have 3 tasks running, we have
- * to switch tasks every 3.33 msecs to get a 10 msecs observed latency
- * for each task. We do finer and finer scheduling up to until we
- * reach the minimum granularity value.
- *
- * To achieve this we use the following dynamic-granularity rule:
+ * The idea is to set a period in which each task runs once.
  *
- *    gran = lat/nr - lat/nr/nr
+ * When there are too many tasks (sysctl_sched_nr_latency) we have to stretch
+ * this period because otherwise the slices get too small.
  *
- * This comes out of the following equations:
- *
- *    kA1 + gran = kB1
- *    kB2 + gran = kA2
- *    kA2 = kA1
- *    kB2 = kB1 - d + d/nr
- *    lat = d * nr
- *
- * Where 'k' is key, 'A' is task A (waiting), 'B' is task B (running),
- * '1' is start of time, '2' is end of time, 'd' is delay between
- * 1 and 2 (during which task B was running), 'nr' is number of tasks
- * running, 'lat' is the the period of each task. ('lat' is the
- * sched_latency that we aim for.)
+ * p = (nr <= nl) ? l : l*nr/nl
  */
-static long
-sched_granularity(struct cfs_rq *cfs_rq)
+static u64 __sched_period(unsigned long nr_running)
 {
-        unsigned int gran = sysctl_sched_latency;
-        unsigned int nr = cfs_rq->nr_running;
+        u64 period = sysctl_sched_latency;
+        unsigned long nr_latency = sysctl_sched_nr_latency;
 
-        if (nr > 1) {
-                gran = gran/nr - gran/nr/nr;
-                gran = max(gran, sysctl_sched_min_granularity);
+        if (unlikely(nr_running > nr_latency)) {
+                period *= nr_running;
+                do_div(period, nr_latency);
         }
 
-        return gran;
+        return period;
 }
 
 /*
- * We rescale the rescheduling granularity of tasks according to their
- * nice level, but only linearly, not exponentially:
+ * We calculate the wall-time slice from the period by taking a part
+ * proportional to the weight.
+ *
+ * s = p*w/rw
  */
-static long
-niced_granularity(struct sched_entity *curr, unsigned long granularity)
+static u64 sched_slice(struct cfs_rq *cfs_rq, struct sched_entity *se)
 {
-        u64 tmp;
+        u64 slice = __sched_period(cfs_rq->nr_running);
 
-        if (likely(curr->load.weight == NICE_0_LOAD))
-                return granularity;
-        /*
-         * Positive nice levels get the same granularity as nice-0:
-         */
-        if (likely(curr->load.weight < NICE_0_LOAD)) {
-                tmp = curr->load.weight * (u64)granularity;
-                return (long) (tmp >> NICE_0_SHIFT);
-        }
-        /*
-         * Negative nice level tasks get linearly finer
-         * granularity:
-         */
-        tmp = curr->load.inv_weight * (u64)granularity;
+        slice *= se->load.weight;
+        do_div(slice, cfs_rq->load.weight);
 
-        /*
-         * It will always fit into 'long':
-         */
-        return (long) (tmp >> (WMULT_SHIFT-NICE_0_SHIFT));
+        return slice;
 }
 
-static inline void
-limit_wait_runtime(struct cfs_rq *cfs_rq, struct sched_entity *se)
+/*
+ * We calculate the vruntime slice.
+ *
+ * vs = s/w = p/rw
+ */
+static u64 __sched_vslice(unsigned long rq_weight, unsigned long nr_running)
 {
-        long limit = sysctl_sched_runtime_limit;
+        u64 vslice = __sched_period(nr_running);
 
-        /*
-         * Niced tasks have the same history dynamic range as
-         * non-niced tasks:
-         */
-        if (unlikely(se->wait_runtime > limit)) {
-                se->wait_runtime = limit;
-                schedstat_inc(se, wait_runtime_overruns);
-                schedstat_inc(cfs_rq, wait_runtime_overruns);
-        }
-        if (unlikely(se->wait_runtime < -limit)) {
-                se->wait_runtime = -limit;
-                schedstat_inc(se, wait_runtime_underruns);
-                schedstat_inc(cfs_rq, wait_runtime_underruns);
-        }
+        do_div(vslice, rq_weight);
+
+        return vslice;
 }
 
-static inline void
-__add_wait_runtime(struct cfs_rq *cfs_rq, struct sched_entity *se, long delta)
+static u64 sched_vslice(struct cfs_rq *cfs_rq)
 {
-        se->wait_runtime += delta;
-        schedstat_add(se, sum_wait_runtime, delta);
-        limit_wait_runtime(cfs_rq, se);
+        return __sched_vslice(cfs_rq->load.weight, cfs_rq->nr_running);
 }
 
-static void
-add_wait_runtime(struct cfs_rq *cfs_rq, struct sched_entity *se, long delta)
+static u64 sched_vslice_add(struct cfs_rq *cfs_rq, struct sched_entity *se)
 {
-        schedstat_add(cfs_rq, wait_runtime, -se->wait_runtime);
-        __add_wait_runtime(cfs_rq, se, delta);
-        schedstat_add(cfs_rq, wait_runtime, se->wait_runtime);
+        return __sched_vslice(cfs_rq->load.weight + se->load.weight,
+                        cfs_rq->nr_running + 1);
 }
 
 /*
@@ -348,46 +280,41 @@ add_wait_runtime(struct cfs_rq *cfs_rq, struct sched_entity *se, long delta)
  * are not in our scheduling class.
  */
 static inline void
-__update_curr(struct cfs_rq *cfs_rq, struct sched_entity *curr)
+__update_curr(struct cfs_rq *cfs_rq, struct sched_entity *curr,
+              unsigned long delta_exec)
 {
-        unsigned long delta, delta_exec, delta_fair, delta_mine;
-        struct load_weight *lw = &cfs_rq->load;
-        unsigned long load = lw->weight;
+        unsigned long delta_exec_weighted;
+        u64 vruntime;
 
-        delta_exec = curr->delta_exec;
         schedstat_set(curr->exec_max, max((u64)delta_exec, curr->exec_max));
 
         curr->sum_exec_runtime += delta_exec;
-        cfs_rq->exec_clock += delta_exec;
-
-        if (unlikely(!load))
-                return;
-
-        delta_fair = calc_delta_fair(delta_exec, lw);
-        delta_mine = calc_delta_mine(delta_exec, curr->load.weight, lw);
-
-        if (cfs_rq->sleeper_bonus > sysctl_sched_min_granularity) {
-                delta = min((u64)delta_mine, cfs_rq->sleeper_bonus);
-                delta = min(delta, (unsigned long)(
-                        (long)sysctl_sched_runtime_limit - curr->wait_runtime));
-                cfs_rq->sleeper_bonus -= delta;
-                delta_mine -= delta;
+        schedstat_add(cfs_rq, exec_clock, delta_exec);
+        delta_exec_weighted = delta_exec;
+        if (unlikely(curr->load.weight != NICE_0_LOAD)) {
+                delta_exec_weighted = calc_delta_fair(delta_exec_weighted,
+                                                        &curr->load);
         }
+        curr->vruntime += delta_exec_weighted;
 
-        cfs_rq->fair_clock += delta_fair;
         /*
-         * We executed delta_exec amount of time on the CPU,
-         * but we were only entitled to delta_mine amount of
-         * time during that period (if nr_running == 1 then
-         * the two values are equal)
-         * [Note: delta_mine - delta_exec is negative]:
+         * maintain cfs_rq->min_vruntime to be a monotonic increasing
+         * value tracking the leftmost vruntime in the tree.
          */
-        add_wait_runtime(cfs_rq, curr, delta_mine - delta_exec);
+        if (first_fair(cfs_rq)) {
+                vruntime = min_vruntime(curr->vruntime,
+                                __pick_next_entity(cfs_rq)->vruntime);
+        } else
+                vruntime = curr->vruntime;
+
+        cfs_rq->min_vruntime =
+                max_vruntime(cfs_rq->min_vruntime, vruntime);
 }
 
 static void update_curr(struct cfs_rq *cfs_rq)
 {
-        struct sched_entity *curr = cfs_rq_curr(cfs_rq);
+        struct sched_entity *curr = cfs_rq->curr;
+        u64 now = rq_of(cfs_rq)->clock;
         unsigned long delta_exec;
 
         if (unlikely(!curr))
@@ -398,135 +325,47 @@ static void update_curr(struct cfs_rq *cfs_rq)
          * since the last time we changed load (this cannot
          * overflow on 32 bits):
          */
-        delta_exec = (unsigned long)(rq_of(cfs_rq)->clock - curr->exec_start);
+        delta_exec = (unsigned long)(now - curr->exec_start);
 
-        curr->delta_exec += delta_exec;
-
-        if (unlikely(curr->delta_exec > sysctl_sched_stat_granularity)) {
-                __update_curr(cfs_rq, curr);
-                curr->delta_exec = 0;
-        }
-        curr->exec_start = rq_of(cfs_rq)->clock;
+        __update_curr(cfs_rq, curr, delta_exec);
+        curr->exec_start = now;
 }
 
 static inline void
 update_stats_wait_start(struct cfs_rq *cfs_rq, struct sched_entity *se)
 {
-        se->wait_start_fair = cfs_rq->fair_clock;
         schedstat_set(se->wait_start, rq_of(cfs_rq)->clock);
 }
 
 /*
- * We calculate fair deltas here, so protect against the random effects
- * of a multiplication overflow by capping it to the runtime limit:
- */
-#if BITS_PER_LONG == 32
-static inline unsigned long
-calc_weighted(unsigned long delta, unsigned long weight, int shift)
-{
-        u64 tmp = (u64)delta * weight >> shift;
-
-        if (unlikely(tmp > sysctl_sched_runtime_limit*2))
-                return sysctl_sched_runtime_limit*2;
-        return tmp;
-}
-#else
-static inline unsigned long
-calc_weighted(unsigned long delta, unsigned long weight, int shift)
-{
-        return delta * weight >> shift;
-}
-#endif
-
-/*
  * Task is being enqueued - update stats:
  */
 static void update_stats_enqueue(struct cfs_rq *cfs_rq, struct sched_entity *se)
 {
-        s64 key;
-
         /*
          * Are we enqueueing a waiting task? (for current tasks
          * a dequeue/enqueue event is a NOP)
          */
-        if (se != cfs_rq_curr(cfs_rq))
+        if (se != cfs_rq->curr)
                 update_stats_wait_start(cfs_rq, se);
-        /*
-         * Update the key:
-         */
-        key = cfs_rq->fair_clock;
-
-        /*
-         * Optimize the common nice 0 case:
-         */
-        if (likely(se->load.weight == NICE_0_LOAD)) {
-                key -= se->wait_runtime;
-        } else {
-                u64 tmp;
-
-                if (se->wait_runtime < 0) {
-                        tmp = -se->wait_runtime;
-                        key += (tmp * se->load.inv_weight) >>
-                                        (WMULT_SHIFT - NICE_0_SHIFT);
-                } else {
-                        tmp = se->wait_runtime;
-                        key -= (tmp * se->load.inv_weight) >>
-                                        (WMULT_SHIFT - NICE_0_SHIFT);
-                }
-        }
-
-        se->fair_key = key;
-}
-
-/*
- * Note: must be called with a freshly updated rq->fair_clock.
- */
-static inline void
-__update_stats_wait_end(struct cfs_rq *cfs_rq, struct sched_entity *se)
-{
-        unsigned long delta_fair = se->delta_fair_run;
-
-        schedstat_set(se->wait_max, max(se->wait_max,
-                        rq_of(cfs_rq)->clock - se->wait_start));
-
-        if (unlikely(se->load.weight != NICE_0_LOAD))
-                delta_fair = calc_weighted(delta_fair, se->load.weight,
-                                                        NICE_0_SHIFT);
-
-        add_wait_runtime(cfs_rq, se, delta_fair);
 }
 
 static void
 update_stats_wait_end(struct cfs_rq *cfs_rq, struct sched_entity *se)
 {
-        unsigned long delta_fair;
-
-        if (unlikely(!se->wait_start_fair))
-                return;
-
-        delta_fair = (unsigned long)min((u64)(2*sysctl_sched_runtime_limit),
-                        (u64)(cfs_rq->fair_clock - se->wait_start_fair));
-
-        se->delta_fair_run += delta_fair;
-        if (unlikely(abs(se->delta_fair_run) >=
-                                sysctl_sched_stat_granularity)) {
-                __update_stats_wait_end(cfs_rq, se);
-                se->delta_fair_run = 0;
-        }
-
-        se->wait_start_fair = 0;
+        schedstat_set(se->wait_max, max(se->wait_max,
+                        rq_of(cfs_rq)->clock - se->wait_start));
         schedstat_set(se->wait_start, 0);
 }
 
 static inline void
 update_stats_dequeue(struct cfs_rq *cfs_rq, struct sched_entity *se)
 {
-        update_curr(cfs_rq);
         /*
          * Mark the end of the wait period if dequeueing a
          * waiting task:
          */
-        if (se != cfs_rq_curr(cfs_rq))
+        if (se != cfs_rq->curr)
                 update_stats_wait_end(cfs_rq, se);
 }
 
@@ -542,79 +381,28 @@ update_stats_curr_start(struct cfs_rq *cfs_rq, struct sched_entity *se)
         se->exec_start = rq_of(cfs_rq)->clock;
 }
 
-/*
- * We are descheduling a task - update its stats:
- */
-static inline void
-update_stats_curr_end(struct cfs_rq *cfs_rq, struct sched_entity *se)
-{
-        se->exec_start = 0;
-}
-
 /**************************************************
  * Scheduling class queueing methods:
  */
 
-static void __enqueue_sleeper(struct cfs_rq *cfs_rq, struct sched_entity *se)
+static void
+account_entity_enqueue(struct cfs_rq *cfs_rq, struct sched_entity *se)
 {
-        unsigned long load = cfs_rq->load.weight, delta_fair;
-        long prev_runtime;
-
-        /*
-         * Do not boost sleepers if there's too much bonus 'in flight'
-         * already:
-         */
-        if (unlikely(cfs_rq->sleeper_bonus > sysctl_sched_runtime_limit))
-                return;
-
-        if (sysctl_sched_features & SCHED_FEAT_SLEEPER_LOAD_AVG)
-                load = rq_of(cfs_rq)->cpu_load[2];
-
-        delta_fair = se->delta_fair_sleep;
-
-        /*
-         * Fix up delta_fair with the effect of us running
-         * during the whole sleep period:
-         */
-        if (sysctl_sched_features & SCHED_FEAT_SLEEPER_AVG)
-                delta_fair = div64_likely32((u64)delta_fair * load,
-                                                load + se->load.weight);
-
-        if (unlikely(se->load.weight != NICE_0_LOAD))
-                delta_fair = calc_weighted(delta_fair, se->load.weight,
-                                                        NICE_0_SHIFT);
-
-        prev_runtime = se->wait_runtime;
-        __add_wait_runtime(cfs_rq, se, delta_fair);
-        delta_fair = se->wait_runtime - prev_runtime;
+        update_load_add(&cfs_rq->load, se->load.weight);
+        cfs_rq->nr_running++;
+        se->on_rq = 1;
+}
 
-        /*
-         * Track the amount of bonus we've given to sleepers:
-         */
-        cfs_rq->sleeper_bonus += delta_fair;
+static void
+account_entity_dequeue(struct cfs_rq *cfs_rq, struct sched_entity *se)
+{
+        update_load_sub(&cfs_rq->load, se->load.weight);
+        cfs_rq->nr_running--;
+        se->on_rq = 0;
 }
 
 static void enqueue_sleeper(struct cfs_rq *cfs_rq, struct sched_entity *se)
 {
-        struct task_struct *tsk = task_of(se);
-        unsigned long delta_fair;
-
-        if ((entity_is_task(se) && tsk->policy == SCHED_BATCH) ||
-                         !(sysctl_sched_features & SCHED_FEAT_FAIR_SLEEPERS))
-                return;
-
-        delta_fair = (unsigned long)min((u64)(2*sysctl_sched_runtime_limit),
-                (u64)(cfs_rq->fair_clock - se->sleep_start_fair));
-
-        se->delta_fair_sleep += delta_fair;
-        if (unlikely(abs(se->delta_fair_sleep) >=
-                                sysctl_sched_stat_granularity)) {
-                __enqueue_sleeper(cfs_rq, se);
-                se->delta_fair_sleep = 0;
-        }
-
-        se->sleep_start_fair = 0;
-
 #ifdef CONFIG_SCHEDSTATS
         if (se->sleep_start) {
                 u64 delta = rq_of(cfs_rq)->clock - se->sleep_start;
@@ -646,6 +434,8 @@ static void enqueue_sleeper(struct cfs_rq *cfs_rq, struct sched_entity *se)
                  * time that the task spent sleeping:
                  */
                 if (unlikely(prof_on == SLEEP_PROFILING)) {
+                        struct task_struct *tsk = task_of(se);
+
                         profile_hits(SLEEP_PROFILING, (void *)get_wchan(tsk),
                                      delta >> 20);
                 }
@@ -653,27 +443,81 @@ static void enqueue_sleeper(struct cfs_rq *cfs_rq, struct sched_entity *se)
 #endif
 }
 
+static void check_spread(struct cfs_rq *cfs_rq, struct sched_entity *se)
+{
+#ifdef CONFIG_SCHED_DEBUG
+        s64 d = se->vruntime - cfs_rq->min_vruntime;
+
+        if (d < 0)
+                d = -d;
+
+        if (d > 3*sysctl_sched_latency)
+                schedstat_inc(cfs_rq, nr_spread_over);
+#endif
+}
+
+static void
+place_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int initial)
+{
+        u64 vruntime;
+
+        vruntime = cfs_rq->min_vruntime;
+
+        if (sched_feat(TREE_AVG)) {
+                struct sched_entity *last = __pick_last_entity(cfs_rq);
+                if (last) {
+                        vruntime += last->vruntime;
+                        vruntime >>= 1;
+                }
+        } else if (sched_feat(APPROX_AVG) && cfs_rq->nr_running)
+                vruntime += sched_vslice(cfs_rq)/2;
+
+        if (initial && sched_feat(START_DEBIT))
+                vruntime += sched_vslice_add(cfs_rq, se);
+
+        if (!initial) {
+                if (sched_feat(NEW_FAIR_SLEEPERS) && entity_is_task(se) &&
+                                task_of(se)->policy != SCHED_BATCH)
+                        vruntime -= sysctl_sched_latency;
+
+                vruntime = max_t(s64, vruntime, se->vruntime);
+        }
+
+        se->vruntime = vruntime;
+
+}
+
 static void
 enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int wakeup)
 {
         /*
-         * Update the fair clock.
+         * Update run-time statistics of the 'current'.
          */
         update_curr(cfs_rq);
 
-        if (wakeup)
+        if (wakeup) {
+                place_entity(cfs_rq, se, 0);
                 enqueue_sleeper(cfs_rq, se);
+        }
 
         update_stats_enqueue(cfs_rq, se);
-        __enqueue_entity(cfs_rq, se);
+        check_spread(cfs_rq, se);
+        if (se != cfs_rq->curr)
+                __enqueue_entity(cfs_rq, se);
+        account_entity_enqueue(cfs_rq, se);
 }
 
 static void
 dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int sleep)
 {
+        /*
+         * Update run-time statistics of the 'current'.
+         */
+        update_curr(cfs_rq);
+
         update_stats_dequeue(cfs_rq, se);
         if (sleep) {
-                se->sleep_start_fair = cfs_rq->fair_clock;
+                se->peer_preempt = 0;
 #ifdef CONFIG_SCHEDSTATS
                 if (entity_is_task(se)) {
                         struct task_struct *tsk = task_of(se);
@@ -685,68 +529,66 @@ dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int sleep)
                 }
 #endif
         }
-        __dequeue_entity(cfs_rq, se);
+
+        if (se != cfs_rq->curr)
+                __dequeue_entity(cfs_rq, se);
+        account_entity_dequeue(cfs_rq, se);
 }
 
 /*
  * Preempt the current task with a newly woken task if needed:
  */
 static void
-__check_preempt_curr_fair(struct cfs_rq *cfs_rq, struct sched_entity *se,
-                          struct sched_entity *curr, unsigned long granularity)
+check_preempt_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr)
 {
-        s64 __delta = curr->fair_key - se->fair_key;
         unsigned long ideal_runtime, delta_exec;
 
-        /*
-         * ideal_runtime is compared against sum_exec_runtime, which is
-         * walltime, hence do not scale.
-         */
-        ideal_runtime = max(sysctl_sched_latency / cfs_rq->nr_running,
-                        (unsigned long)sysctl_sched_min_granularity);
-
-        /*
-         * If we executed more than what the latency constraint suggests,
-         * reduce the rescheduling granularity. This way the total latency
-         * of how much a task is not scheduled converges to
-         * sysctl_sched_latency:
-         */
+        ideal_runtime = sched_slice(cfs_rq, curr);
         delta_exec = curr->sum_exec_runtime - curr->prev_sum_exec_runtime;
-        if (delta_exec > ideal_runtime)
-                granularity = 0;
-
-        /*
-         * Take scheduling granularity into account - do not
-         * preempt the current task unless the best task has
-         * a larger than sched_granularity fairness advantage:
-         *
-         * scale granularity as key space is in fair_clock.
-         */
-        if (__delta > niced_granularity(curr, granularity))
+        if (delta_exec > ideal_runtime ||
+                        (sched_feat(PREEMPT_RESTRICT) && curr->peer_preempt))
                 resched_task(rq_of(cfs_rq)->curr);
+        curr->peer_preempt = 0;
 }
 
-static inline void
+static void
 set_next_entity(struct cfs_rq *cfs_rq, struct sched_entity *se)
 {
+        /* 'current' is not kept within the tree. */
+        if (se->on_rq) {
+                /*
+                 * Any task has to be enqueued before it get to execute on
+                 * a CPU. So account for the time it spent waiting on the
+                 * runqueue.
+                 */
+                update_stats_wait_end(cfs_rq, se);
+                __dequeue_entity(cfs_rq, se);
+        }
+
+        update_stats_curr_start(cfs_rq, se);
+        cfs_rq->curr = se;
+#ifdef CONFIG_SCHEDSTATS
         /*
-         * Any task has to be enqueued before it get to execute on
-         * a CPU. So account for the time it spent waiting on the
-         * runqueue. (note, here we rely on pick_next_task() having
-         * done a put_prev_task_fair() shortly before this, which
-         * updated rq->fair_clock - used by update_stats_wait_end())
+         * Track our maximum slice length, if the CPU's load is at
+         * least twice that of our own weight (i.e. dont track it
+         * when there are only lesser-weight tasks around):
          */
-        update_stats_wait_end(cfs_rq, se);
-        update_stats_curr_start(cfs_rq, se);
-        set_cfs_rq_curr(cfs_rq, se);
+        if (rq_of(cfs_rq)->load.weight >= 2*se->load.weight) {
+                se->slice_max = max(se->slice_max,
+                        se->sum_exec_runtime - se->prev_sum_exec_runtime);
+        }
+#endif
         se->prev_sum_exec_runtime = se->sum_exec_runtime;
 }
 
 static struct sched_entity *pick_next_entity(struct cfs_rq *cfs_rq)
 {
-        struct sched_entity *se = __pick_next_entity(cfs_rq);
+        struct sched_entity *se = NULL;
 
-        set_next_entity(cfs_rq, se);
+        if (first_fair(cfs_rq)) {
+                se = __pick_next_entity(cfs_rq);
+                set_next_entity(cfs_rq, se);
+        }
 
         return se;
 }
@@ -760,33 +602,24 @@ static void put_prev_entity(struct cfs_rq *cfs_rq, struct sched_entity *prev)
         if (prev->on_rq)
                 update_curr(cfs_rq);
 
-        update_stats_curr_end(cfs_rq, prev);
-
-        if (prev->on_rq)
+        check_spread(cfs_rq, prev);
+        if (prev->on_rq) {
                 update_stats_wait_start(cfs_rq, prev);
-        set_cfs_rq_curr(cfs_rq, NULL);
+                /* Put 'current' back into the tree. */
+                __enqueue_entity(cfs_rq, prev);
+        }
+        cfs_rq->curr = NULL;
 }
 
 static void entity_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr)
 {
-        struct sched_entity *next;
-
         /*
-         * Dequeue and enqueue the task to update its
-         * position within the tree:
+         * Update run-time statistics of the 'current'.
          */
-        dequeue_entity(cfs_rq, curr, 0);
-        enqueue_entity(cfs_rq, curr, 0);
-
-        /*
-         * Reschedule if another task tops the current one.
-         */
-        next = __pick_next_entity(cfs_rq);
-        if (next == curr)
-                return;
+        update_curr(cfs_rq);
 
-        __check_preempt_curr_fair(cfs_rq, next, curr,
-                        sched_granularity(cfs_rq));
+        if (cfs_rq->nr_running > 1 || !sched_feat(WAKEUP_PREEMPT))
+                check_preempt_tick(cfs_rq, curr);
 }
 
 /**************************************************
@@ -821,23 +654,28 @@ static inline struct cfs_rq *group_cfs_rq(struct sched_entity *grp)
  */
 static inline struct cfs_rq *cpu_cfs_rq(struct cfs_rq *cfs_rq, int this_cpu)
 {
-        /* A later patch will take group into account */
-        return &cpu_rq(this_cpu)->cfs;
+        return cfs_rq->tg->cfs_rq[this_cpu];
 }
 
 /* Iterate thr' all leaf cfs_rq's on a runqueue */
 #define for_each_leaf_cfs_rq(rq, cfs_rq) \
         list_for_each_entry(cfs_rq, &rq->leaf_cfs_rq_list, leaf_cfs_rq_list)
 
-/* Do the two (enqueued) tasks belong to the same group ? */
-static inline int is_same_group(struct task_struct *curr, struct task_struct *p)
+/* Do the two (enqueued) entities belong to the same group ? */
+static inline int
+is_same_group(struct sched_entity *se, struct sched_entity *pse)
 {
-        if (curr->se.cfs_rq == p->se.cfs_rq)
+        if (se->cfs_rq == pse->cfs_rq)
                 return 1;
 
         return 0;
 }
 
+static inline struct sched_entity *parent_entity(struct sched_entity *se)
+{
+        return se->parent;
+}
+
 #else   /* CONFIG_FAIR_GROUP_SCHED */
 
 #define for_each_sched_entity(se) \
@@ -870,11 +708,17 @@ static inline struct cfs_rq *cpu_cfs_rq(struct cfs_rq *cfs_rq, int this_cpu)
 #define for_each_leaf_cfs_rq(rq, cfs_rq) \
                 for (cfs_rq = &rq->cfs; cfs_rq; cfs_rq = NULL)
 
-static inline int is_same_group(struct task_struct *curr, struct task_struct *p)
+static inline int
+is_same_group(struct sched_entity *se, struct sched_entity *pse)
 {
         return 1;
 }
 
+static inline struct sched_entity *parent_entity(struct sched_entity *se)
+{
+        return NULL;
+}
+
 #endif  /* CONFIG_FAIR_GROUP_SCHED */
 
 /*
@@ -892,6 +736,7 @@ static void enqueue_task_fair(struct rq *rq, struct task_struct *p, int wakeup)
                         break;
                 cfs_rq = cfs_rq_of(se);
                 enqueue_entity(cfs_rq, se, wakeup);
+                wakeup = 1;
         }
 }
 
@@ -911,6 +756,7 @@ static void dequeue_task_fair(struct rq *rq, struct task_struct *p, int sleep)
                 /* Don't dequeue parent if it has other entities besides us */
                 if (cfs_rq->load.weight)
                         break;
+                sleep = 1;
         }
 }
 
@@ -919,12 +765,10 @@ static void dequeue_task_fair(struct rq *rq, struct task_struct *p, int sleep)
  *
  * If compat_yield is turned on then we requeue to the end of the tree.
  */
-static void yield_task_fair(struct rq *rq, struct task_struct *p)
+static void yield_task_fair(struct rq *rq)
 {
-        struct cfs_rq *cfs_rq = task_cfs_rq(p);
-        struct rb_node **link = &cfs_rq->tasks_timeline.rb_node;
-        struct sched_entity *rightmost, *se = &p->se;
-        struct rb_node *parent;
+        struct cfs_rq *cfs_rq = task_cfs_rq(rq->curr);
+        struct sched_entity *rightmost, *se = &rq->curr->se;
 
         /*
          * Are we the only task in the tree?
@@ -935,52 +779,39 @@ static void yield_task_fair(struct rq *rq, struct task_struct *p)
         if (likely(!sysctl_sched_compat_yield)) {
                 __update_rq_clock(rq);
                 /*
-                 * Dequeue and enqueue the task to update its
-                 * position within the tree:
+                 * Update run-time statistics of the 'current'.
                  */
-                dequeue_entity(cfs_rq, &p->se, 0);
-                enqueue_entity(cfs_rq, &p->se, 0);
+                update_curr(cfs_rq);
 
                 return;
         }
         /*
          * Find the rightmost entry in the rbtree:
          */
-        do {
-                parent = *link;
-                link = &parent->rb_right;
-        } while (*link);
-
-        rightmost = rb_entry(parent, struct sched_entity, run_node);
+        rightmost = __pick_last_entity(cfs_rq);
         /*
          * Already in the rightmost position?
          */
-        if (unlikely(rightmost == se))
+        if (unlikely(rightmost->vruntime < se->vruntime))
                 return;
 
         /*
          * Minimally necessary key value to be last in the tree:
+         * Upon rescheduling, sched_class::put_prev_task() will place
+         * 'current' within the tree based on its new key value.
          */
-        se->fair_key = rightmost->fair_key + 1;
-
-        if (cfs_rq->rb_leftmost == &se->run_node)
-                cfs_rq->rb_leftmost = rb_next(&se->run_node);
-        /*
-         * Relink the task to the rightmost position:
-         */
-        rb_erase(&se->run_node, &cfs_rq->tasks_timeline);
-        rb_link_node(&se->run_node, parent, link);
-        rb_insert_color(&se->run_node, &cfs_rq->tasks_timeline);
+        se->vruntime = rightmost->vruntime + 1;
 }
 
 /*
  * Preempt the current task with a newly woken task if needed:
  */
-static void check_preempt_curr_fair(struct rq *rq, struct task_struct *p)
+static void check_preempt_wakeup(struct rq *rq, struct task_struct *p)
 {
         struct task_struct *curr = rq->curr;
         struct cfs_rq *cfs_rq = task_cfs_rq(curr);
-        unsigned long gran;
+        struct sched_entity *se = &curr->se, *pse = &p->se;
+        s64 delta, gran;
 
         if (unlikely(rt_prio(p->prio))) {
                 update_rq_clock(rq);
@@ -988,16 +819,31 @@ static void check_preempt_curr_fair(struct rq *rq, struct task_struct *p)
                 resched_task(curr);
                 return;
         }
-
-        gran = sysctl_sched_wakeup_granularity;
         /*
-         * Batch tasks prefer throughput over latency:
+         * Batch tasks do not preempt (their preemption is driven by
+         * the tick):
          */
         if (unlikely(p->policy == SCHED_BATCH))
-                gran = sysctl_sched_batch_wakeup_granularity;
+                return;
+
+        if (sched_feat(WAKEUP_PREEMPT)) {
+                while (!is_same_group(se, pse)) {
+                        se = parent_entity(se);
+                        pse = parent_entity(pse);
+                }
 
-        if (is_same_group(curr, p))
-                __check_preempt_curr_fair(cfs_rq, &p->se, &curr->se, gran);
+                delta = se->vruntime - pse->vruntime;
+                gran = sysctl_sched_wakeup_granularity;
+                if (unlikely(se->load.weight != NICE_0_LOAD))
+                        gran = calc_delta_fair(gran, &se->load);
+
+                if (delta > gran) {
+                        int now = !sched_feat(PREEMPT_RESTRICT);
+
+                        if (now || p->prio < curr->prio || !se->peer_preempt++)
+                                resched_task(curr);
+                }
+        }
 }
 
 static struct task_struct *pick_next_task_fair(struct rq *rq)
@@ -1041,7 +887,7 @@ static void put_prev_task_fair(struct rq *rq, struct task_struct *prev)
  * achieve that by always pre-iterating before returning
  * the current task:
  */
-static inline struct task_struct *
+static struct task_struct *
 __load_balance_iterator(struct cfs_rq *cfs_rq, struct rb_node *curr)
 {
         struct task_struct *p;
@@ -1078,7 +924,10 @@ static int cfs_rq_best_prio(struct cfs_rq *cfs_rq)
         if (!cfs_rq->nr_running)
                 return MAX_PRIO;
 
-        curr = __pick_next_entity(cfs_rq);
+        curr = cfs_rq->curr;
+        if (!curr)
+                curr = __pick_next_entity(cfs_rq);
+
         p = task_of(curr);
 
         return p->prio;
@@ -1153,6 +1002,8 @@ static void task_tick_fair(struct rq *rq, struct task_struct *curr)
         }
 }
 
+#define swap(a,b) do { typeof(a) tmp = (a); (a) = (b); (b) = tmp; } while (0)
+
 /*
  * Share the fairness runtime between parent and child, thus the
  * total amount of pressure for CPU stays equal - new tasks
@@ -1163,37 +1014,32 @@ static void task_tick_fair(struct rq *rq, struct task_struct *curr)
 static void task_new_fair(struct rq *rq, struct task_struct *p)
 {
         struct cfs_rq *cfs_rq = task_cfs_rq(p);
-        struct sched_entity *se = &p->se, *curr = cfs_rq_curr(cfs_rq);
+        struct sched_entity *se = &p->se, *curr = cfs_rq->curr;
+        int this_cpu = smp_processor_id();
 
         sched_info_queued(p);
 
         update_curr(cfs_rq);
-        update_stats_enqueue(cfs_rq, se);
-        /*
-         * Child runs first: we let it run before the parent
-         * until it reschedules once. We set up the key so that
-         * it will preempt the parent:
-         */
-        se->fair_key = curr->fair_key -
-                niced_granularity(curr, sched_granularity(cfs_rq)) - 1;
-        /*
-         * The first wait is dominated by the child-runs-first logic,
-         * so do not credit it with that waiting time yet:
-         */
-        if (sysctl_sched_features & SCHED_FEAT_SKIP_INITIAL)
-                se->wait_start_fair = 0;
+        place_entity(cfs_rq, se, 1);
 
-        /*
-         * The statistical average of wait_runtime is about
-         * -granularity/2, so initialize the task with that:
-         */
-        if (sysctl_sched_features & SCHED_FEAT_START_DEBIT)
-                se->wait_runtime = -(sched_granularity(cfs_rq) / 2);
+        if (sysctl_sched_child_runs_first && this_cpu == task_cpu(p) &&
+                        curr->vruntime < se->vruntime) {
+                /*
+                 * Upon rescheduling, sched_class::put_prev_task() will place
+                 * 'current' within the tree based on its new key value.
+                 */
+                swap(curr->vruntime, se->vruntime);
+        }
 
+        update_stats_enqueue(cfs_rq, se);
+        check_spread(cfs_rq, se);
+        check_spread(cfs_rq, curr);
         __enqueue_entity(cfs_rq, se);
+        account_entity_enqueue(cfs_rq, se);
+        se->peer_preempt = 0;
+        resched_task(rq->curr);
 }
 
-#ifdef CONFIG_FAIR_GROUP_SCHED
 /* Account for a task changing its policy or group.
  *
  * This routine is mostly called to set cfs_rq->curr field when a task
@@ -1206,21 +1052,17 @@ static void set_curr_task_fair(struct rq *rq)
         for_each_sched_entity(se)
                 set_next_entity(cfs_rq_of(se), se);
 }
-#else
-static void set_curr_task_fair(struct rq *rq)
-{
-}
-#endif
 
 /*
  * All the scheduling class methods:
  */
-struct sched_class fair_sched_class __read_mostly = {
+static const struct sched_class fair_sched_class = {
+        .next                   = &idle_sched_class,
         .enqueue_task           = enqueue_task_fair,
         .dequeue_task           = dequeue_task_fair,
         .yield_task             = yield_task_fair,
 
-        .check_preempt_curr     = check_preempt_curr_fair,
+        .check_preempt_curr     = check_preempt_wakeup,
 
         .pick_next_task         = pick_next_task_fair,
         .put_prev_task          = put_prev_task_fair,
@@ -1237,6 +1079,9 @@ static void print_cfs_stats(struct seq_file *m, int cpu)
 {
         struct cfs_rq *cfs_rq;
 
+#ifdef CONFIG_FAIR_GROUP_SCHED
+        print_cfs_rq(m, cpu, &cpu_rq(cpu)->cfs);
+#endif
         for_each_leaf_cfs_rq(cpu_rq(cpu), cfs_rq)
                 print_cfs_rq(m, cpu, cfs_rq);
 }