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Date:	Tue, 14 Nov 2006 12:33:06 -0800 (PST)
From:	Christoph Lameter <>
Cc:	Peter Williams <>,,
	Nick Piggin <>,
	Christoph Lameter <>,
	KAMEZAWA Hiroyuki <>,
	"Chen, Kenneth W" <>,
	Ingo Molnar <>,
	"Siddha, Suresh B" <>
Subject: [PATCH 2/8] Remove staggering of load balancing

Remove load staggering.

Timer interrupts already are staggered. We do not need an additional
layer of time staggering for short load balancing actions that take a
reasonably small portion of the time slice.

For load balancing on large sched_domains we will add a serialization
later that avoids concurrent load balance operations and thus has
the same effect as load staggering.

Signed-off-by: Christoph Lameter <>

Index: linux-2.6.19-rc5-mm1/kernel/sched.c
--- linux-2.6.19-rc5-mm1.orig/kernel/sched.c	2006-11-10 22:47:56.305271903 -0600
+++ linux-2.6.19-rc5-mm1/kernel/sched.c	2006-11-10 22:48:09.002647332 -0600
@@ -2844,16 +2844,10 @@ static void active_load_balance(struct r
  * Balancing parameters are set up in arch_init_sched_domains.
-/* Don't have all balancing operations going off at once: */
-static inline unsigned long cpu_offset(int cpu)
-	return jiffies + cpu * HZ / NR_CPUS;
 static void
 rebalance_tick(int this_cpu, struct rq *this_rq, enum idle_type idle)
-	unsigned long this_load, interval, j = cpu_offset(this_cpu);
+	unsigned long this_load, interval;
 	struct sched_domain *sd;
 	int i, scale;
@@ -2888,7 +2882,7 @@ rebalance_tick(int this_cpu, struct rq *
 		if (unlikely(!interval))
 			interval = 1;
-		if (j - sd->last_balance >= interval) {
+		if (jiffies - sd->last_balance >= interval) {
 			if (load_balance(this_cpu, this_rq, sd, idle)) {
 				 * We've pulled tasks over so either we're no
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