1 files changed, 171 insertions, 76 deletions

diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c
index e24ecd39c4b..f2aa987027d 100644
--- a/kernel/sched_fair.c
+++ b/kernel/sched_fair.c
@@ -63,13 +63,13 @@ unsigned int __read_mostly sysctl_sched_compat_yield;
 
 /*
  * SCHED_OTHER wake-up granularity.
- * (default: 10 msec * (1 + ilog(ncpus)), units: nanoseconds)
+ * (default: 5 msec * (1 + ilog(ncpus)), 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 = 10000000UL;
+unsigned int sysctl_sched_wakeup_granularity = 5000000UL;
 
 const_debug unsigned int sysctl_sched_migration_cost = 500000UL;
 
@@ -429,12 +429,38 @@ calc_delta_asym(unsigned long delta, struct sched_entity *se)
 
 	for_each_sched_entity(se) {
 		struct load_weight *se_lw = &se->load;
+		unsigned long rw = cfs_rq_of(se)->load.weight;
+
+#ifdef CONFIG_FAIR_SCHED_GROUP
+		struct cfs_rq *cfs_rq = se->my_q;
+		struct task_group *tg = NULL
+
+		if (cfs_rq)
+			tg = cfs_rq->tg;
+
+		if (tg && tg->shares < NICE_0_LOAD) {
+			/*
+			 * scale shares to what it would have been had
+			 * tg->weight been NICE_0_LOAD:
+			 *
+			 *   weight = 1024 * shares / tg->weight
+			 */
+			lw.weight *= se->load.weight;
+			lw.weight /= tg->shares;
+
+			lw.inv_weight = 0;
 
-		if (se->load.weight < NICE_0_LOAD)
 			se_lw = &lw;
+			rw += lw.weight - se->load.weight;
+		} else
+#endif
 
-		delta = calc_delta_mine(delta,
-				cfs_rq_of(se)->load.weight, se_lw);
+		if (se->load.weight < NICE_0_LOAD) {
+			se_lw = &lw;
+			rw += NICE_0_LOAD - se->load.weight;
+		}
+
+		delta = calc_delta_mine(delta, rw, se_lw);
 	}
 
 	return delta;
@@ -700,21 +726,6 @@ enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int wakeup)
 		__enqueue_entity(cfs_rq, se);
 }
 
-static void update_avg(u64 *avg, u64 sample)
-{
-	s64 diff = sample - *avg;
-	*avg += diff >> 3;
-}
-
-static void update_avg_stats(struct cfs_rq *cfs_rq, struct sched_entity *se)
-{
-	if (!se->last_wakeup)
-		return;
-
-	update_avg(&se->avg_overlap, se->sum_exec_runtime - se->last_wakeup);
-	se->last_wakeup = 0;
-}
-
 static void
 dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int sleep)
 {
@@ -725,7 +736,6 @@ dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int sleep)
 
 	update_stats_dequeue(cfs_rq, se);
 	if (sleep) {
-		update_avg_stats(cfs_rq, se);
 #ifdef CONFIG_SCHEDSTATS
 		if (entity_is_task(se)) {
 			struct task_struct *tsk = task_of(se);
@@ -787,17 +797,16 @@ set_next_entity(struct cfs_rq *cfs_rq, struct sched_entity *se)
 	se->prev_sum_exec_runtime = se->sum_exec_runtime;
 }
 
-static int
-wakeup_preempt_entity(struct sched_entity *curr, struct sched_entity *se);
-
 static struct sched_entity *
 pick_next(struct cfs_rq *cfs_rq, struct sched_entity *se)
 {
-	if (!cfs_rq->next)
-		return se;
+	struct rq *rq = rq_of(cfs_rq);
+	u64 pair_slice = rq->clock - cfs_rq->pair_start;
 
-	if (wakeup_preempt_entity(cfs_rq->next, se) != 0)
+	if (!cfs_rq->next || pair_slice > sched_slice(cfs_rq, cfs_rq->next)) {
+		cfs_rq->pair_start = rq->clock;
 		return se;
+	}
 
 	return cfs_rq->next;
 }
@@ -896,7 +905,7 @@ static void hrtick_start_fair(struct rq *rq, struct task_struct *p)
 		hrtick_start(rq, delta, requeue);
 	}
 }
-#else
+#else /* !CONFIG_SCHED_HRTICK */
 static inline void
 hrtick_start_fair(struct rq *rq, struct task_struct *p)
 {
@@ -1037,7 +1046,7 @@ static int wake_idle(int cpu, struct task_struct *p)
 	}
 	return cpu;
 }
-#else
+#else /* !ARCH_HAS_SCHED_WAKE_IDLE*/
 static inline int wake_idle(int cpu, struct task_struct *p)
 {
 	return cpu;
@@ -1048,6 +1057,89 @@ static inline int wake_idle(int cpu, struct task_struct *p)
 
 static const struct sched_class fair_sched_class;
 
+#ifdef CONFIG_FAIR_GROUP_SCHED
+/*
+ * effective_load() calculates the load change as seen from the root_task_group
+ *
+ * Adding load to a group doesn't make a group heavier, but can cause movement
+ * of group shares between cpus. Assuming the shares were perfectly aligned one
+ * can calculate the shift in shares.
+ *
+ * The problem is that perfectly aligning the shares is rather expensive, hence
+ * we try to avoid doing that too often - see update_shares(), which ratelimits
+ * this change.
+ *
+ * We compensate this by not only taking the current delta into account, but
+ * also considering the delta between when the shares were last adjusted and
+ * now.
+ *
+ * We still saw a performance dip, some tracing learned us that between
+ * cgroup:/ and cgroup:/foo balancing the number of affine wakeups increased
+ * significantly. Therefore try to bias the error in direction of failing
+ * the affine wakeup.
+ *
+ */
+static long effective_load(struct task_group *tg, int cpu,
+		long wl, long wg)
+{
+	struct sched_entity *se = tg->se[cpu];
+	long more_w;
+
+	if (!tg->parent)
+		return wl;
+
+	/*
+	 * By not taking the decrease of shares on the other cpu into
+	 * account our error leans towards reducing the affine wakeups.
+	 */
+	if (!wl && sched_feat(ASYM_EFF_LOAD))
+		return wl;
+
+	/*
+	 * Instead of using this increment, also add the difference
+	 * between when the shares were last updated and now.
+	 */
+	more_w = se->my_q->load.weight - se->my_q->rq_weight;
+	wl += more_w;
+	wg += more_w;
+
+	for_each_sched_entity(se) {
+#define D(n) (likely(n) ? (n) : 1)
+
+		long S, rw, s, a, b;
+
+		S = se->my_q->tg->shares;
+		s = se->my_q->shares;
+		rw = se->my_q->rq_weight;
+
+		a = S*(rw + wl);
+		b = S*rw + s*wg;
+
+		wl = s*(a-b)/D(b);
+		/*
+		 * Assume the group is already running and will
+		 * thus already be accounted for in the weight.
+		 *
+		 * That is, moving shares between CPUs, does not
+		 * alter the group weight.
+		 */
+		wg = 0;
+#undef D
+	}
+
+	return wl;
+}
+
+#else
+
+static inline unsigned long effective_load(struct task_group *tg, int cpu,
+		unsigned long wl, unsigned long wg)
+{
+	return wl;
+}
+
+#endif
+
 static int
 wake_affine(struct rq *rq, struct sched_domain *this_sd, struct rq *this_rq,
 	    struct task_struct *p, int prev_cpu, int this_cpu, int sync,
@@ -1055,36 +1147,50 @@ wake_affine(struct rq *rq, struct sched_domain *this_sd, struct rq *this_rq,
 	    unsigned int imbalance)
 {
 	struct task_struct *curr = this_rq->curr;
+	struct task_group *tg;
 	unsigned long tl = this_load;
 	unsigned long tl_per_task;
+	unsigned long weight;
+	int balanced;
 
-	if (!(this_sd->flags & SD_WAKE_AFFINE))
+	if (!(this_sd->flags & SD_WAKE_AFFINE) || !sched_feat(AFFINE_WAKEUPS))
 		return 0;
 
 	/*
+	 * If sync wakeup then subtract the (maximum possible)
+	 * effect of the currently running task from the load
+	 * of the current CPU:
+	 */
+	if (sync) {
+		tg = task_group(current);
+		weight = current->se.load.weight;
+
+		tl += effective_load(tg, this_cpu, -weight, -weight);
+		load += effective_load(tg, prev_cpu, 0, -weight);
+	}
+
+	tg = task_group(p);
+	weight = p->se.load.weight;
+
+	balanced = 100*(tl + effective_load(tg, this_cpu, weight, weight)) <=
+		imbalance*(load + effective_load(tg, prev_cpu, 0, weight));
+
+	/*
 	 * If the currently running task will sleep within
 	 * a reasonable amount of time then attract this newly
 	 * woken task:
 	 */
-	if (sync && curr->sched_class == &fair_sched_class) {
+	if (sync && balanced) {
 		if (curr->se.avg_overlap < sysctl_sched_migration_cost &&
-				p->se.avg_overlap < sysctl_sched_migration_cost)
+		    p->se.avg_overlap < sysctl_sched_migration_cost)
 			return 1;
 	}
 
 	schedstat_inc(p, se.nr_wakeups_affine_attempts);
 	tl_per_task = cpu_avg_load_per_task(this_cpu);
 
-	/*
-	 * If sync wakeup then subtract the (maximum possible)
-	 * effect of the currently running task from the load
-	 * of the current CPU:
-	 */
-	if (sync)
-		tl -= current->se.load.weight;
-
 	if ((tl <= load && tl + target_load(prev_cpu, idx) <= tl_per_task) ||
-			100*(tl + p->se.load.weight) <= imbalance*load) {
+			balanced) {
 		/*
 		 * This domain has SD_WAKE_AFFINE and
 		 * p is cache cold in this domain, and
@@ -1172,7 +1278,10 @@ static unsigned long wakeup_gran(struct sched_entity *se)
 	 * More easily preempt - nice tasks, while not making it harder for
 	 * + nice tasks.
 	 */
-	gran = calc_delta_asym(sysctl_sched_wakeup_granularity, se);
+	if (sched_feat(ASYM_GRAN))
+		gran = calc_delta_asym(sysctl_sched_wakeup_granularity, se);
+	else
+		gran = calc_delta_fair(sysctl_sched_wakeup_granularity, se);
 
 	return gran;
 }
@@ -1234,7 +1343,6 @@ static void check_preempt_wakeup(struct rq *rq, struct task_struct *p)
 		return;
 	}
 
-	se->last_wakeup = se->sum_exec_runtime;
 	if (unlikely(se == pse))
 		return;
 
@@ -1332,23 +1440,18 @@ __load_balance_iterator(struct cfs_rq *cfs_rq, struct list_head *next)
 	struct task_struct *p = NULL;
 	struct sched_entity *se;
 
-	if (next == &cfs_rq->tasks)
-		return NULL;
-
-	/* Skip over entities that are not tasks */
-	do {
+	while (next != &cfs_rq->tasks) {
 		se = list_entry(next, struct sched_entity, group_node);
 		next = next->next;
-	} while (next != &cfs_rq->tasks && !entity_is_task(se));
 
-	if (next == &cfs_rq->tasks)
-		return NULL;
+		/* Skip over entities that are not tasks */
+		if (entity_is_task(se)) {
+			p = task_of(se);
+			break;
+		}
+	}
 
 	cfs_rq->balance_iterator = next;
-
-	if (entity_is_task(se))
-		p = task_of(se);
-
 	return p;
 }
 
@@ -1395,40 +1498,32 @@ load_balance_fair(struct rq *this_rq, int this_cpu, struct rq *busiest,
 	struct task_group *tg;
 
 	rcu_read_lock();
+	update_h_load(busiest_cpu);
+
 	list_for_each_entry(tg, &task_groups, list) {
-		long imbalance;
-		unsigned long this_weight, busiest_weight;
-		long rem_load, max_load, moved_load;
+		struct cfs_rq *busiest_cfs_rq = tg->cfs_rq[busiest_cpu];
+		unsigned long busiest_h_load = busiest_cfs_rq->h_load;
+		unsigned long busiest_weight = busiest_cfs_rq->load.weight;
+		u64 rem_load, moved_load;
 
 		/*
 		 * empty group
 		 */
-		if (!aggregate(tg, sd)->task_weight)
+		if (!busiest_cfs_rq->task_weight)
 			continue;
 
-		rem_load = rem_load_move * aggregate(tg, sd)->rq_weight;
-		rem_load /= aggregate(tg, sd)->load + 1;
+		rem_load = (u64)rem_load_move * busiest_weight;
+		rem_load = div_u64(rem_load, busiest_h_load + 1);
 
-		this_weight = tg->cfs_rq[this_cpu]->task_weight;
-		busiest_weight = tg->cfs_rq[busiest_cpu]->task_weight;
-
-		imbalance = (busiest_weight - this_weight) / 2;
-
-		if (imbalance < 0)
-			imbalance = busiest_weight;
-
-		max_load = max(rem_load, imbalance);
 		moved_load = __load_balance_fair(this_rq, this_cpu, busiest,
-				max_load, sd, idle, all_pinned, this_best_prio,
+				rem_load, sd, idle, all_pinned, this_best_prio,
 				tg->cfs_rq[busiest_cpu]);
 
 		if (!moved_load)
 			continue;
 
-		move_group_shares(tg, sd, busiest_cpu, this_cpu);
-
-		moved_load *= aggregate(tg, sd)->load;
-		moved_load /= aggregate(tg, sd)->rq_weight + 1;
+		moved_load *= busiest_h_load;
+		moved_load = div_u64(moved_load, busiest_weight + 1);
 
 		rem_load_move -= moved_load;
 		if (rem_load_move < 0)
@@ -1474,7 +1569,7 @@ move_one_task_fair(struct rq *this_rq, int this_cpu, struct rq *busiest,
 
 	return 0;
 }
-#endif
+#endif /* CONFIG_SMP */
 
 /*
  * scheduler tick hitting a task of our scheduling class: