Index: linux-2.6.19-rc4-mm2/include/asm-ia64/topology.h
===================================================================
--- linux-2.6.19-rc4-mm2.orig/include/asm-ia64/topology.h	2006-11-10 21:13:20.554975620 -0600
+++ linux-2.6.19-rc4-mm2/include/asm-ia64/topology.h	2006-11-10 22:46:45.395884734 -0600
@@ -101,6 +101,7 @@ void build_cpu_to_node_map(void);
 	.flags			= SD_LOAD_BALANCE	\
 				| SD_BALANCE_EXEC	\
 				| SD_BALANCE_FORK	\
+				| SD_SERIALIZE		\
 				| SD_WAKE_BALANCE,	\
 	.last_balance		= jiffies,		\
 	.balance_interval	= 64,			\
Index: linux-2.6.19-rc4-mm2/include/linux/sched.h
===================================================================
--- linux-2.6.19-rc4-mm2.orig/include/linux/sched.h	2006-11-10 21:13:20.090092031 -0600
+++ linux-2.6.19-rc4-mm2/include/linux/sched.h	2006-11-10 22:46:45.495502632 -0600
@@ -647,6 +647,7 @@ enum idle_type
 #define SD_SHARE_CPUPOWER	128	/* Domain members share cpu power */
 #define SD_POWERSAVINGS_BALANCE	256	/* Balance for power savings */
 #define SD_SHARE_PKG_RESOURCES	512	/* Domain members share cpu pkg resources */
+#define SD_SERIALIZE		1024	/* Only a single load balancing instance */
 
 #define BALANCE_FOR_MC_POWER	\
 	(sched_smt_power_savings ? SD_POWERSAVINGS_BALANCE : 0)
Index: linux-2.6.19-rc4-mm2/include/linux/topology.h
===================================================================
--- linux-2.6.19-rc4-mm2.orig/include/linux/topology.h	2006-11-10 22:45:24.408486940 -0600
+++ linux-2.6.19-rc4-mm2/include/linux/topology.h	2006-11-10 22:46:45.531638536 -0600
@@ -194,7 +194,8 @@
 	.wake_idx		= 0, /* unused */	\
 	.forkexec_idx		= 0, /* unused */	\
 	.per_cpu_gain		= 100,			\
-	.flags			= SD_LOAD_BALANCE,	\
+	.flags			= SD_LOAD_BALANCE	\
+				| SD_SERIALIZE,	\
 	.last_balance		= jiffies,		\
 	.balance_interval	= 64,			\
 	.nr_balance_failed	= 0,			\
Index: linux-2.6.19-rc4-mm2/kernel/sched.c
===================================================================
--- linux-2.6.19-rc4-mm2.orig/kernel/sched.c	2006-11-10 22:46:29.518549748 -0600
+++ linux-2.6.19-rc4-mm2/kernel/sched.c	2006-11-10 22:46:45.659579170 -0600
@@ -2871,6 +2871,7 @@ static void run_rebalance_domains(struct
 	struct rq *this_rq = cpu_rq(this_cpu);
 	unsigned long interval;
 	struct sched_domain *sd;
+	static atomic_t nr_balancing = ATOMIC_INIT(0);
 	/*
 	 * We are idle if there are no processes running. This
 	 * is valid even if we are the idle process (SMT).
@@ -2893,6 +2894,11 @@ static void run_rebalance_domains(struct
 		if (unlikely(!interval))
 			interval = 1;
 
+		if (sd->flags & SD_SERIALIZE) {
+			if (!atomic_add_unless(&nr_balancing, 1, 1))
+				 goto out;
+		}
+
 		if (time_after_eq(jiffies, sd->last_balance + interval)) {
 			if (load_balance(this_cpu, this_rq, sd, idle)) {
 				/*
@@ -2904,6 +2910,10 @@ static void run_rebalance_domains(struct
 			}
 			sd->last_balance = jiffies;
 		}
+
+		if (sd->flags & SD_SERIALIZE)
+			atomic_dec(&nr_balancing);
+out:
 		/*
 		 * Calculate the next balancing point assuming that
 		 * the idle state does not change. If we are idle and then