From b1d7c10555292830cd7bbc7ceadf8ea0afffa914 Mon Sep 17 00:00:00 2001
From: Peter Zijlstra <a.p.zijlstra@chello.nl>
Date: Fri, 27 Jun 2008 13:41:35 +0200
Subject: [PATCH] --- yaml --- r: 100237 b: refs/heads/master c:
 2398f2c6d34b43025f274fc42eaca34d23ec2320 h: refs/heads/master i:   100235:
 6a9a261775c10195bb25657fddc38e0446043720 v: v3

---
 [refs]                        |  2 +-
 trunk/include/linux/sched.h   |  3 +++
 trunk/kernel/sched.c          | 30 +++++++++++++++++++++++++++++-
 trunk/kernel/sched_features.h |  3 ++-
 trunk/kernel/sysctl.c         |  8 ++++++++
 5 files changed, 43 insertions(+), 3 deletions(-)

diff --git a/[refs] b/[refs]
index bc94ef80c818..195f9b9a8b9e 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: cd80917e4ff465ea77106f8e4fb631eedc4cf426
+refs/heads/master: 2398f2c6d34b43025f274fc42eaca34d23ec2320
diff --git a/trunk/include/linux/sched.h b/trunk/include/linux/sched.h
index eaf821072dbd..835b6c6fcc56 100644
--- a/trunk/include/linux/sched.h
+++ b/trunk/include/linux/sched.h
@@ -783,6 +783,8 @@ struct sched_domain {
 	unsigned int balance_interval;	/* initialise to 1. units in ms. */
 	unsigned int nr_balance_failed; /* initialise to 0 */
 
+	u64 last_update;
+
 #ifdef CONFIG_SCHEDSTATS
 	/* load_balance() stats */
 	unsigned int lb_count[CPU_MAX_IDLE_TYPES];
@@ -1605,6 +1607,7 @@ extern unsigned int sysctl_sched_child_runs_first;
 extern unsigned int sysctl_sched_features;
 extern unsigned int sysctl_sched_migration_cost;
 extern unsigned int sysctl_sched_nr_migrate;
+extern unsigned int sysctl_sched_shares_ratelimit;
 
 int sched_nr_latency_handler(struct ctl_table *table, int write,
 		struct file *file, void __user *buffer, size_t *length,
diff --git a/trunk/kernel/sched.c b/trunk/kernel/sched.c
index 1cff969f6646..62db0891025a 100644
--- a/trunk/kernel/sched.c
+++ b/trunk/kernel/sched.c
@@ -777,6 +777,12 @@ late_initcall(sched_init_debug);
  */
 const_debug unsigned int sysctl_sched_nr_migrate = 32;
 
+/*
+ * ratelimit for updating the group shares.
+ * default: 0.5ms
+ */
+const_debug unsigned int sysctl_sched_shares_ratelimit = 500000;
+
 /*
  * period over which we measure -rt task cpu usage in us.
  * default: 1s
@@ -1590,7 +1596,13 @@ tg_nop(struct task_group *tg, int cpu, struct sched_domain *sd)
 
 static void update_shares(struct sched_domain *sd)
 {
-	walk_tg_tree(tg_nop, tg_shares_up, 0, sd);
+	u64 now = cpu_clock(raw_smp_processor_id());
+	s64 elapsed = now - sd->last_update;
+
+	if (elapsed >= (s64)(u64)sysctl_sched_shares_ratelimit) {
+		sd->last_update = now;
+		walk_tg_tree(tg_nop, tg_shares_up, 0, sd);
+	}
 }
 
 static void update_shares_locked(struct rq *rq, struct sched_domain *sd)
@@ -2199,6 +2211,22 @@ static int try_to_wake_up(struct task_struct *p, unsigned int state, int sync)
 	if (!sched_feat(SYNC_WAKEUPS))
 		sync = 0;
 
+#ifdef CONFIG_SMP
+	if (sched_feat(LB_WAKEUP_UPDATE)) {
+		struct sched_domain *sd;
+
+		this_cpu = raw_smp_processor_id();
+		cpu = task_cpu(p);
+
+		for_each_domain(this_cpu, sd) {
+			if (cpu_isset(cpu, sd->span)) {
+				update_shares(sd);
+				break;
+			}
+		}
+	}
+#endif
+
 	smp_wmb();
 	rq = task_rq_lock(p, &flags);
 	old_state = p->state;
diff --git a/trunk/kernel/sched_features.h b/trunk/kernel/sched_features.h
index d56e3053e746..7d616d2a2a3f 100644
--- a/trunk/kernel/sched_features.h
+++ b/trunk/kernel/sched_features.h
@@ -8,4 +8,5 @@ SCHED_FEAT(SYNC_WAKEUPS, 1)
 SCHED_FEAT(HRTICK, 1)
 SCHED_FEAT(DOUBLE_TICK, 0)
 SCHED_FEAT(ASYM_GRAN, 1)
-SCHED_FEAT(LB_BIAS, 0)
\ No newline at end of file
+SCHED_FEAT(LB_BIAS, 0)
+SCHED_FEAT(LB_WAKEUP_UPDATE, 1)
diff --git a/trunk/kernel/sysctl.c b/trunk/kernel/sysctl.c
index 29116652dca8..fe8cdc80ff02 100644
--- a/trunk/kernel/sysctl.c
+++ b/trunk/kernel/sysctl.c
@@ -264,6 +264,14 @@ static struct ctl_table kern_table[] = {
 		.extra1		= &min_wakeup_granularity_ns,
 		.extra2		= &max_wakeup_granularity_ns,
 	},
+	{
+		.ctl_name	= CTL_UNNUMBERED,
+		.procname	= "sched_shares_ratelimit",
+		.data		= &sysctl_sched_shares_ratelimit,
+		.maxlen		= sizeof(unsigned int),
+		.mode		= 0644,
+		.proc_handler	= &proc_dointvec,
+	},
 	{
 		.ctl_name	= CTL_UNNUMBERED,
 		.procname	= "sched_child_runs_first",