[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>
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@ -2841,16 +2841,10 @@ static void active_load_balance(struct rq *busiest_rq, int busiest_cpu)
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* Balancing parameters are set up in arch_init_sched_domains.
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* Balancing parameters are set up in arch_init_sched_domains.
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*/
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*/
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/* Don't have all balancing operations going off at once: */
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static inline unsigned long cpu_offset(int cpu)
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{
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return jiffies + cpu * HZ / NR_CPUS;
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}
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static void
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static void
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rebalance_tick(int this_cpu, struct rq *this_rq, enum idle_type idle)
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rebalance_tick(int this_cpu, struct rq *this_rq, enum idle_type idle)
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{
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{
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unsigned long this_load, interval, j = cpu_offset(this_cpu);
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unsigned long this_load, interval;
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struct sched_domain *sd;
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struct sched_domain *sd;
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int i, scale;
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int i, scale;
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@ -2885,7 +2879,7 @@ rebalance_tick(int this_cpu, struct rq *this_rq, enum idle_type idle)
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if (unlikely(!interval))
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if (unlikely(!interval))
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interval = 1;
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interval = 1;
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if (j - sd->last_balance >= interval) {
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if (jiffies - sd->last_balance >= interval) {
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if (load_balance(this_cpu, this_rq, sd, idle)) {
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if (load_balance(this_cpu, this_rq, sd, idle)) {
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/*
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/*
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* We've pulled tasks over so either we're no
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* We've pulled tasks over so either we're no
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