X-Git-Url: http://pileus.org/git/?a=blobdiff_plain;f=kernel%2Fsched_fair.c;h=f2aa987027d695750f2ca4b8f917d02171eeb3b8;hb=873a6ed6288b6c2c0d2cc84d3b2bf2fab9ba0181;hp=bed2f71e63d9168318b1143326638ae43dad3aba;hpb=83378269a5fad98f562ebc0f09c349575e6cbfe1;p=~andy%2Flinux

diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c
index bed2f71e63d..f2aa987027d 100644
--- a/kernel/sched_fair.c
+++ b/kernel/sched_fair.c
@@ -726,21 +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)
 {
@@ -751,7 +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);
@@ -921,7 +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)
 {
@@ -1062,7 +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;
@@ -1074,10 +1058,50 @@ static inline int wake_idle(int cpu, struct task_struct *p)
 static const struct sched_class fair_sched_class;
 
 #ifdef CONFIG_FAIR_GROUP_SCHED
-static unsigned long effective_load(struct task_group *tg, int cpu,
-		unsigned long wl, unsigned long wg)
+/*
+ * 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)
@@ -1086,7 +1110,7 @@ static unsigned long effective_load(struct task_group *tg, int cpu,
 
 		S = se->my_q->tg->shares;
 		s = se->my_q->shares;
-		rw = se->my_q->load.weight;
+		rw = se->my_q->rq_weight;
 
 		a = S*(rw + wl);
 		b = S*rw + s*wg;
@@ -1156,9 +1180,9 @@ wake_affine(struct rq *rq, struct sched_domain *this_sd, struct rq *this_rq,
 	 * a reasonable amount of time then attract this newly
 	 * woken task:
 	 */
-	if (sync && balanced && 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;
 	}
 
@@ -1319,7 +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;
 
@@ -1546,7 +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: