Commit 4211a9a2 authored Dec 10, 2006 by Christoph Lameter Committed by Linus Torvalds Dec 10, 2006

[PATCH] sched: remove staggering of load balancing



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 <clameter@sgi.com>
Cc: Peter Williams <pwil3058@bigpond.net.au>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Christoph Lameter <clameter@sgi.com>
Cc: "Siddha, Suresh B" <suresh.b.siddha@intel.com>
Cc: "Chen, Kenneth W" <kenneth.w.chen@intel.com>
Acked-by: Ingo Molnar <mingo@elte.hu>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

parent 571f6d2f

kernel/sched.c

+2 −8

Original line number	Diff line number	Diff line
		@@ -2841,16 +2841,10 @@ static void active_load_balance(struct rq *busiest_rq, int busiest_cpu)
		* 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;

		@@ -2885,7 +2879,7 @@ rebalance_tick(int this_cpu, struct rq *this_rq, enum idle_type idle)
		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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